Abstract

This paper presents an ultrasensitive temperature sensor and tunable mode converter based on an isopropanol-sealed modal interferometer in a two-mode fiber. The modal interferometer consists of a tapered two-mode fiber (TTMF) sandwiched between two single-mode fibers. The sensor provides high-sensitivity temperature sensing by taking advantages of TTMF, isopropanol and the Vernier-like effect. The TTMF provides a uniform modal interferometer with LP01 and LP11 modes as well as strong evanescent field on its surface. The temperature sensitivity of the sensor can be improved due to the high thermo-optic coefficient of isopropanol. The Vernier-like effect based on the overlap of two interference spectra is applied to magnify the sensing capabilities with a sensitivity magnification factor of 58.5. The temperature sensor is implemented by inserting the modal interferometer into an isopropanol-sealed capillary. The experimental and calculated results show the transmission spectrum exhibit blue shift with increasing ambient temperature. Experimental results show that the isopropanol-sealed modal interferometer provides a temperature sensitivity up to -140.5 nm/°C. The interference spectrum has multiple dips at which the input LP01 mode is converted to the LP11 mode. This modal interferometer acts as a tunable multi-channel mode converter. The mode converter that can be tuned by varying temperature and mode switch is realized.

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

Accurate temperature measurement plays an important role in various applications such as chemical reactions, biomedicine, and industrial production. Fiber temperature sensors have many advantages such as compact size, low cost, immunity to electromagnetic interference, and durability against harsh environment etc. [13]. In addition, mode division multiplexing (MDM) is a promising approach to overcome the limitations of the transmission capacity [4]. The all-fiber mode converter has a key application in the MDM communication system [58].

Fiber optic temperature sensors utilizing different sensing schemes have been extensively investigated such as Fabry-Perot interferometers [9,10], Mach-Zehnder interferometers [11], fiber gratings [12,13], multimode interference (MMI) devices [14], and whispering gallery resonators [15,16]. The typical MMI based sensor is fabricated by splicing a section of multimode fiber between two single-mode fibers (SMFs) with a structure of single mode-multimode-single mode fiber [17]. Many higher-order modes exist in the tapered multimode fiber. The MMI occurs among high-order core modes. In the tapered multimode fiber, the fraction of power in the evanescent wave within the cladding was increased. However, more than two cladding modes interfering with the fundamental mode would lead to a low extinction ratio (ER) or a small free spectral range (FSR), which limits the sensing performance [1820]. The tapered two-mode fiber (TTMF) sandwiched between two SMFs has been reported for high-sensitivity magnetic field sensor [18], detection of IgG operating near the dispersion turning point [19], temperature sensor based on the Vernier effect [20], wavelength switchable mode-locked fiber laser [21], and refractive index sensing [22]. In the TTMF, high extinction ratio and uniform modal interferometer just involved with the LP01 and LP11 modes can be achieved.

In the different sensing schemes, however, the temperature sensitivity is limited by the relatively low thermal expansion coefficient and thermo-optic coefficient of silica fiber. Various temperature sensitive materials have been reported to improve temperature sensitivity, such as graphene [23], PDMS [15], polymeric materials [17], and isopropyl alcohol [2426]. Among the thermo-optical materials, isopropanol has a higher thermo-optical coefficient and rapid decreases of refractive index with the increment of external temperature [24]. This points to a possible approach to implement an ultrasensitive temperature sensor with isopropanol-sealed modal interferometer consists of a TTMF.

In order to magnify the sensing capability of an interferometer, the Vernier effect has been applied for fiber sensors [10,27,28]. With the Vernier effect, the spectral shift can be magnified by the beating pattern containing a large envelope. The beating pattern is produced by the superposition of the responses from two interferometers with slightly shifted interferometric frequencies. Therefore, ultrahigh sensitivities and resolutions can be realized using the Vernier effect [10]. The Vernier effect has been applied to various structures for a diverse range of sensing applications such as Sagnac interferometers [27], optical fiber Fabry–Perot interferometers (FPIs) [29,30] and Mach-Zehnder interferometers (MZIs) [31,32]. Temperature sensitivity of 1.964 nm/°C in a range from 10 to 70 °C has been achieved with a temperature sensor based on two cascaded MZIs using the Vernier effect [33]. A temperature sensor with online controllable sensitivity based on the Vernier effect can achieve sensitivity of -14.63 nm/°C [34]. A temperature sensor with TTMFs based on the Vernier effect providing sensitivity of -3.348 nm/°C in a temperature measurement range from 25 °C to 60 °C has been reported. Compared with single TTMF, its sensitivity is enhanced by 11.3 times [20]. Generally, the Vernier effect needs two interferometers, one interferometer is used as a reference and the other is used as a sensor. However, because the two interferometers are located physically close to one another, it is difficult to maintain one interferometer as a stable reference [10]. In addition, two interferometers introduce additional insertion loss. Using the Vernier effect for ultrasensitive sensing with one interferometer is promising.

In this paper, to the best of our knowledge, we demonstrate for the first time an ultrasensitive temperature sensor and tunable mode converter based on an isopropanol-sealed modal interferometer in a two-mode fiber (TMF). The ultrasensitive temperature sensor is realized combining the advantages of TTMF, isopropanol and the Vernier-like effect. The TTMF provides a uniform modal interferometer with LP01 and LP11 modes and strong evanescent field on its surface. The isopropanol has a higher thermo-optical coefficient and the Vernier-like effect realized with one TTMF magnifies the sensing capability of the temperature sensor. The interferometer is fabricated by splicing a section of TMF between two SMFs. The temperature sensor is implemented by inserting the modal interferometer into an isopropanol-sealed capillary. The temperature sensor has the highest sensitivity of -140.5nm/°C. In addition, this modal interferometer acts as a tunable multi-channel mode converter for LP01 and LP11 modes conversion. The mode converter can be tuned by varying the temperature due to refractive index change of isopropanol.

2. Device fabrication and theoretical principle

2.1 Fabrication of the isopropanol-sealed modal interferometer

Figure 1 shows the schematic of the isopropanol-sealed modal interferometer. It consists of an input SMF, a down-taper region, a TTMF section, an up-taper region, and an output SMF. The TMF supports the LP01 and LP11 modes. The modal interferometer was encapsulated by isopropanol (Shanghai Macklin Biochemical, I811925) filled quartz capillary. Tapering the TMF is an efficient way to achieve a uniform modal interference mainly involving the LP01 and LP11 modes. There are three steps for the fabrication of the temperature sensor, as shown in Fig. 2(a-d). Initially, a segment of TMF (YOFC, FM SI-2) with a length of 5 cm was spliced with SMFs (Coring, SMF-28e) at the input and outputs ends forming an SMF-TMF-SMF configuration. Then the flame-brushing technique was applied to fabricate the TTMF. The pulling speed, pulling time and hydrogen flow rate were controlled to obtain a uniform interference spectrum. The waist diameter of the tapered TMF decreases with the increase of the stretching length. The size of modal interferometer is chosen considering the FSR and insertion loss. A smaller FSR provides higher sensitivity [20]. The FSR of the interference spectrum depends on the waist diameter, the length of the uniform waist and the length of the down-taper region. The TTMF with a waist diameter of 7.4 μm was produced, and the length of the down-taper region and uniform waist are 1.5 mm and 9.0 mm, respectively. The microscope image of the TTMF with a uniform waist is shown in Fig. 2(e). Next, the prepared TTMF was placed into a quartz capillary of 75 mm length and 1.8 mm inner diameter. The isopropanol was injected into the quartz capillary with a syringe. Isopropanol is a kind of thermo-optic material that has a thermo-optic coefficient of $- 4.5 \times {10^{ - 4}}\; /^\circ \textrm{C}$. Isopropanol also has small viscosity, and it is easy to fill the capillary through the capillary effect, which is easy for fabrication and device packaging [35]. The TTMF was completely immersed in the isopropanol environment. After that, both ends of the quartz capillary were sealed with UV glue (LOCTITE, AA352) for preventing the isopropanol from leaking or evaporating. The UV glue only covers the SMF part and does not affect and contact the tapered region. The entire device was straightly glued on a glass slide to maintain stability.

 figure: Fig. 1.

Fig. 1. Schematic of the proposed isopropanol-sealed modal interferometer.

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 figure: Fig. 2.

Fig. 2. (a)-(d) Schematic diagram of the device fabrication process. (e) The microscope image of the TTMF with a uniform waist.

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Figure 3 shows the typical transmission spectra of the modal interferometer in air and isopropanol. The modal interferometer has stable comb spectra. When the modal interferometer is immersed in isopropanol, the FSR of the interference spectrum increases due to the increase of the external refractive index (next). At 1550 nm, the transmission spectrum in the air has an ER of 10.9 dB and FSR of 7.4 nm. For the transmission spectrum in isopropanol at 1550 nm, the ER is 11.1 dB and FSR is 11.4 nm. In order to investigate the stability of this device, we measured the output interference spectra of the isopropanol-sealed modal interferometer. At room temperature of 26°C, the ER is nearly not changed, and deviation of the dip wavelengths is smaller than 0.8 nm for 5 days. The leaking or evaporating of isopropanol in the quartz capillary may cause the deviation of the dip wavelengths. This can be improved by sealing the ends of the quartz capillary with UV glue that cannot be dissolved by the isopropanol and using advanced packaging methods.

 figure: Fig. 3.

Fig. 3. Transmission spectra of the modal interferometer in air and in isopropanol.

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2.2 Theoretical principle of the temperature sensor

The LP11 modes in a TMF can be excited with a lateral offset splicing [36,37] and introducing lateral stress points [38]. We introduce a tapered region into the TMF to excite high-order modes. The tapered region is composed of two conical transition tapers and a uniform waist region, as shown in Fig. 1. At the down-taper region, the core diameter of the TMF decreases to a certain value, the input LP01 mode is partly coupled into the LP11 mode. The LP01 and LP11 modes in the TTMF are coupled to guided-cladding modes in the uniform waist region. Strong evanescent fields exist around the TTMF, enabling strong interaction between the surrounding environment and light. At the up-taper region, part of the LP11 mode is coupled back to the LP01 mode, at the same time part of the LP01 mode is coupled to the LP11 mode. The phase difference is generated between the LP01 and LP11 modes as a result of propagation constant difference, resulting in a uniform comb interference spectrum. The transmission spectra of the modal interferometer can be expressed as

$$I = {I_1} + {I_2} + 2\sqrt {{I_1}{I_2}} \textrm{cos}({\Delta \varphi } )$$
where I1 and I2 are the intensity of LP01 and LP11 modes respectively. $\Delta \varphi $ represents the phase difference between the two modes. The effective index difference between the LP01 and LP11 modes is $\Delta {n_{eff}} = {n_{eff01}} - {n_{eff11}}$. The phase difference between the LP01 and LP11 modes is
$$\Delta \varphi = \frac{{2\pi \Delta {n_{eff}}L}}{\lambda }$$
where L is the length of the taper, and λ is the wavelength. In addition, the FSR of the interference spectrum can be expressed as
$$FSR = \frac{{{\lambda ^2}}}{{\mathrm{\Delta }{n_{eff}}L}}$$
The effective indices of LP01 and LP11 modes vary with the next of the TTMF and the interference spectrum shifts accordingly. The temperature sensitivity can be written as
$$S = \frac{{d\lambda }}{{d{n_{ext}}}} = \lambda \cdot \frac{1}{\mathrm{\Gamma }}\left( {\frac{1}{{\mathrm{\Delta }{n_{eff}}}}\frac{{d\mathrm{\Delta }{n_{eff}}}}{{d{n_{ext}}}}} \right)$$

The temperature sensitivity is determined by the dispersion factor Γ, the external refractive index induced variation of effective index difference $({d\mathrm{\Delta }{n_{eff}}} )/({d{n_{ext}}\; } )$, and λ [18]. The refractive index of the isopropanol decreases significantly when temperature increases. The decrease of ${n_{ext}}$ results in the reduction of the effective index of the LP01 mode $({\mathrm{\Delta }{n_{eff01}}} )$ and the LP11 mode $({\mathrm{\Delta }{n_{eff11}}} )$, and $\mathrm{\Delta }{n_{eff11}}$ is larger than $\mathrm{\Delta }{n_{eff01}}$ because the LP01 mode is more confined in the fiber core. As a result, $({d\mathrm{\Delta }{n_{eff}}} )/({d{n_{ext}}} )> 0$. In addition, Γ<0 in the wavelength region. Therefore, a negative S is enabled, corresponding to a blue shift of wavelengths with an increase of temperature.

With the 3D finite-difference beam propagation method (3DFD-BPM) (BeamPROP, RSoft), numerical simulations were performed to investigate the interference spectrum and sensitivity of the temperature sensor. In the simulation, the length of the down-taper region and the waist region of the TTMF are 1.1 mm and 9.5 mm, respectively, and the diameter of the waist region is 7.0 μm. Figure 4 shows the calculated transmission spectra of the modal interferometer under temperatures of 32 °C, 33 °C, 34 °C and 35 °C for the refractive indices of 1.36980, 1.36935, 1.36890 and 1.36845, respectively [24]. The modal interferometer has uniform comb spectra. The ER and FSR of the spectra are 9.6 dB and 12.5 nm, respectively. When the surrounding temperature increases, the wavelengths show blue shift. The calculated temperature sensitivity is -2.7 nm/°C.

 figure: Fig. 4.

Fig. 4. Calculated transmission spectra of the modal interference under various temperatures.

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3. Experimental results and discussion

3.1 Temperature sensing

The experimental setup for temperature measurement is shown in Fig. 5. Light from a broadband light source (NKT Photonics, SuperK COMPACT) was launched into the SMF port of the temperature sensor. The interference spectrum was recorded by an optical spectrum analyzer (OSA) (Yokogawa, AQ6370D). The OSA has a scan range of 600-1700nm and a resolution of 10 pm. A tubular temperature control with a resolution of 0.1 °C was applied to control the surrounding temperature of the packaged temperature sensor. Figure 6 shows the measured transmission spectra for modal interferometer without isopropanol as the temperature increased from 35 °C to 60 °C with a step of 5 °C. The FSR and maximum ER of the spectra at 1525 nm are 9.4 nm and 14.8 dB, respectively. For each step, the temperature was kept for 3 min, then the transmission spectra were recorded. The blue shift of the transmission spectrum induced by temperature change is small (-0.2 nm/°C). The shift of the transmission spectrum of the modal interferometer without isopropanol is caused by the thermo-optic effect of silica. In the temperature measurement range (35 °C-60 °C), the shift of the transmission spectrum is 5 nm which is smaller than the FSR.

 figure: Fig. 5.

Fig. 5. Schematic of the experimental setup for temperature tests.

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 figure: Fig. 6.

Fig. 6. The measured transmission spectra for modal interferometer without isopropanol at different temperatures.

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Then the transmission spectra of modal interferometer sealed with isopropanol were measured. Figures 7 (a) and (b) typically display the wavelength shift of the transmission spectra in different wavelength range as temperature increased from 30 °C to 55 °C with a step of 5 °C. In the wavelength range 1300-1380 nm at 30 °C, the FSR and maximum ER of the spectrum are 10.6 nm and 18.8 dB, respectively. In the wavelength range 1600-1680 nm at 30 °C, the FSR and maximum ER of the spectrum are 12.2 nm and 13.1 dB, respectively. The external temperature increment leads to a reduction of the refractive index of isopropanol, which results in the transmission spectrum shift. The wavelength dips experience a marked blue shift as temperature increase. The wavelength dips exhibit good fringe contrast and linear shift with increasing temperature. As shown in Fig. 7(a), with temperature increases from 30 °C to 55 °C, the wavelength dip shifts from 1358.2 nm to 1322.8 nm. The wavelength dip shifts from 1677.8 nm to 1618.0 nm in Fig. 7(b). Wavelength dips at larger wavelengths provide higher sensitivity [39,40]. The temperature sensitivities for 1360 nm and 1670 nm are -1.4 nm/°C and -2.4 nm/°C over the range of 30 °C-55 °C, respectively. Similar results were obtained by measuring the transmission spectra at different temperatures with a step of 1°C.

 figure: Fig. 7.

Fig. 7. The measured transmission spectra for modal interferometer sealed with isopropanol at different temperatures in the wavelength range (a)1300-1380 nm and (b) 1600-1680 nm.

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The FSR of the interference spectrum of the modal interferometer decreases as the temperature increases. As shown in Fig. 8(a), as the temperature increase from 20 °C to 60 °C, the FSR of the interference spectrum at the wavelength range 1300-1700nm decreases from 11.5 nm to 10.6 nm. In addition, the FSR depends on wavelength. As shown in the linear fitting curve of Fig. 8(b), the FSR increases with the wavelength.

 figure: Fig. 8.

Fig. 8. (a) Averaged FSR in 1300-1700 nm of the interference spectrum of the modal interferometer as a function temperature, (b) FSR (at 30 °C) of the interference spectrum of the modal interferometer as a function wavelength.

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In order to magnify the sensing capability of the temperature sensor, the Vernier-like effect was applied in our experiment. The Vernier-like effect based on the overlap of two interference spectra is applied to magnify the sensing capabilities. The interference spectrum of the temperature sensor at specific temperature is used as a reference. The Vernier-like effect is realized with the superposition of the interference spectrum and the reference spectrum, producing a beating pattern containing a large envelope [10,20]. Compared with one interference spectrum, the large envelope provides the spectral shift magnification. Therefore, ultrahigh sensitivity can be achieved. Under the magnification of the Vernier effect, the magnification factor can be expressed as

$$M = \frac{{{S_{envelope}}}}{S}$$
where Senvelope is the sensitivity of the envelope, S is the sensitivity of the one normal modal interferometer.

The blue curves in Figs. 9(a)-(d) show the measured spectra with Vernier-like effect [10,20]. The interference spectrum of the temperature sensor at 22 °C serves as a reference. The spectra shown in Fig. 9 were obtained by superposition of the reference spectrum and individual spectrum at different temperatures with an OSA during the experiment. In Fig. 9(a), the spectra were obtained by superposition of the spectrum under 22 °C and the spectra under temperatures from 28 °C to 32 °C with the OSA. This Vernier-like effect for temperature sensing is simple and only one modal interferometer was used. The commonly used Vernier effect requires two interferometers that are located physically close to one another, and it is difficult to maintain one interferometer as a stable reference. As shown in Fig. 9, the envelope of the spectrum is denoted by a dashed line. The nodes marked by an arrow are used to track the wavelength shift. In different temperature range, various nodes can be observed in the wavelength range from 1000 nm to 1700 nm. Figure 9(a) shows Node 1 and Node 2 under temperatures from 28 °C to 32 °C. Node 2 and Node 3 are observed under temperatures from 33 °C to 37 °C as shown in Fig. 9(b). Figure 9(c) shows Node 3, Node 4 and Node 5 under temperatures from 45 °C to 49 °C. Node 4, Node 5, Node 6 and Node 7 are observed under temperatures from 53 °C to 57 °C as shown in Fig. 9(d). With temperature increases, the nodes show blue shift. This is because the FSR of the interference spectrum of the modal interferometer decreases when temperature increases.

 figure: Fig. 9.

Fig. 9. Measured spectra of the temperature sensor with Vernier-like effect for temperatures (a) from 28 °C to 32 °C, (b) from 33 °C to 37 °C, (c) from 45 °C to 49 °C, (d) from 53 °C to 57 °C.

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In different temperature range, the nodes are tracked to investigate the temperature sensitivity. With temperature increases, it can be seen from the linear fitting curve in Fig. 10, different nodes have different sensitivities. Lower temperatures provide higher temperature sensitivities. The temperature sensitivities for Node 1-Node 7 are -140.5 nm/°C, -65.4 nm/°C, -40.3 nm/°C, -28.1 nm/°C, -26.3 nm/°C, -26.2 nm/°C and -25.8 nm/°C, respectively. This is because the modal interferometer has higher sensitivity in higher next corresponding to lower temperature [41]. In practical applications, according to the temperature range, different nodes can be selected for temperature sensing. In contrast, the temperature sensitivity of the modal interferometer without the Vernier-like effect is -2.4 nm/°C. The sensitivity of the sensor with Vernier-like effect is much higher than the sensor without the Vernier-like effect, exhibiting a sensitivity magnification factor of 58.5.

 figure: Fig. 10.

Fig. 10. Linear fitting of wavelength shift versus temperature for the temperature sensor with Vernier-like effect.

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Compared with other reported fiber temperature sensors, which are based on microfiber ring resonator (MRR) [15], two-mode microfiber knot resonator (TMM-KR) [16], double TTMF [20], microfiber (MF) coupler [24], MF [35], and multimode microfiber(MMMF) [42], our temperature sensor has much higher sensitivity, as listed in Table 1. The TTMF, the isopropanol and the Vernier-like effect contribute to the ultrahigh sensitivity of our proposed sensor. With the TTMF, strong evanescent field on its surface and uniform modal interferometer with LP01 and LP11 modes are achieved. The isopropanol with high thermo-optic coefficient provides great refractive index change with temperature variation. With the Vernier-like effect, the spectral shift of the modal interferometer is magnified by the beating pattern containing a large envelope.

Tables Icon

Table 1. Sensitivity comparison with other temperature sensing structures and materials.

3.2 Thermo-optical mode conversion

The modal interferometer can act as a multi-channel mode converter for mode conversion from the LP01 to the LP11 mode in the TMF. Mode conversion requires phase matching between the LP01 and LP11 modes. The modal interferometer has multiple phase matching points, enabling mode conversion at multi-channel wavelengths. Figure 11 illustrates the experimental setup for measuring the near-field mode patterns of the mode converter. After the interference spectrum of the modal interferometer was obtained with the experimental setup shown in Fig. 5, the output SMF of the modal interferometer was cut off. The light from a tunable laser (TL) (Yokogawa, AQ2211) was launched into the SMF input of the isopropanol-sealed modal interferometer which is put into a tubular temperature control. The near-field mode patterns from the output TMF were inspected with a CCD (New Imaging Technologies, WIDY SWIR 640 US). A ×20 microscope objective (MO) lens was used to focus light into the CCD. A polarization controller (PC) was applied at the input to change the polarization state of light. We selected four typical wavelengths of the interference spectrum under 26 °C for investigation, including the four dips (1537.2 nm, 1558.8 nm, 1580.8 nm, 1602.8 nm) and three peaks (1548 nm, 1570 nm, 1592 nm) marked with the red circle. Figure 12 illustrates the captured near-field output patterns at the dips and peaks of the interference spectrum. Clear LP11 mode can be obtained by appropriately adjusting the PC. When the PC is adjusted, the interference spectrum remains the same, but the output mode patterns from the TMF are changed [38]. The mode patterns prove that the LP01 mode is completely converted into the LP11 mode at the dips in the transmission spectra. At the peaks of the transmission spectra, the LP01 mode cannot be converted into the LP11 mode. At the wavelengths of 1537.2 nm, 1558.8 nm, 1580.8 nm and 1602.8 nm, the near-field output patterns are pure LP11 modes. At the wavelengths of 1548 nm, 1570 nm and 1592 nm, the near-field output patterns are pure LP01 modes. The results prove the LP01 mode is completely converted to the LP11 mode at the dips of the interference spectrum. The conversion efficiency for the 8 dip wavelengths in the wavelength range from 1450 nm to 1620 nm is larger than 99.49% [38].

 figure: Fig. 11.

Fig. 11. Schematic of the experimental setup for measuring the near-field output patterns.

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 figure: Fig. 12.

Fig. 12. Near-field patterns at the dips and peaks of the interference spectrum under 26 °C.

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Using the thermo-optical characteristic of isopropanol, the mode converter can be tuned by varying the temperature. This is because the wavelengths of the interference spectrum exhibit blue shift with increasing temperature. As shown in Fig. 13, at the dip wavelength 1546 nm, the output mode patterns change with temperature. At 25.9 °C, the output is a pure LP11 mode, and it changes to a LP01 mode at 35.5 °C. The wavelength 1546 nm corresponds to a peak of the interference spectrum under 35.5 °C. When the temperature is 39.7 °C, the LP11 mode appeared again, the wavelength 1546 nm evolves into a dip of the interference spectrum. At 46.8 °C, the output is a LP01 mode, the wavelength 1546 nm changed to a peak of the interference spectrum. By changing the temperature, a mode switch was achieved.

 figure: Fig. 13.

Fig. 13. Output mode patterns at 1546 nm with different temperatures.

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4. Conclusions

In this paper, we have proposed an ultrasensitive temperature sensor and tunable mode converter based on an isopropanol-sealed modal interferometer formed with a section of TMF between two SMFs. We have presented experimental and calculated results on the wavelength shift of the transmission spectrum of the temperature sensor with ambient temperature change. With the temperature increasing, the dip wavelength exhibits a prominent blue shift. The temperature sensor is fabricated by encapsulating a modal interferometer into an isopropanol filled quartz capillary. The TTMF provides strong evanescent field on its surface and a uniform modal interferometer with LP01 and LP11 modes. The high thermo-optic coefficient of the isopropanol enables great refractive index change of the isopropanol with temperature variation. With the Vernier-like effect, the spectral shift is magnified by the beating pattern containing a large envelope. In our experiments, the sensor has a temperature sensitivity up to -140.5 nm/°C. The uniform interference spectrum exhibited multiple dips at which mode conversion between the LP01 mode and LP11 mode is achieved. This mode converter can be tuned by varying temperature and the mode switch is realized. This device can be applied in highly sensitive temperature sensing applications including healthcare, consumer electronics, and MDM systems.

Funding

National Natural Science Foundation of China (61505069, 61705087, 61705089, 61775084, 62075088); NSAF (U2030103); Guangdong Special Support Program (2016TQ03X962); Natural Science Foundation of Guangdong Province (2020A151501791, 2021A0505030036, 2021A1515011875); Open Fund of Guangdong Provincial Key Laboratory of Information Photonics Technology of the Guangdong University of Technology (GKPT20-03); Fundamental Research Funds for the Central Universities (11620444).

Disclosures

The authors declare that there are no conflicts of interest related to this article.

Data availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

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16. A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019). [CrossRef]  

17. Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014). [CrossRef]  

18. B. Sun, F. Fang, Z. Zhang, J. Xu, and L. Zhang, “High-sensitivity and low-temperature magnetic field sensor based on tapered two-mode fiber interference,” Opt. Lett. 43(6), 1311–1314 (2018). [CrossRef]  

19. B. Sun and Y. Wang, “High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers,” Micromachines 11(3), 270 (2020). [CrossRef]  

20. L. Xie, B. Sun, M. Chen, and Z. Zhang, “Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect,” Opt. Express 28(22), 32447–32455 (2020). [CrossRef]  

21. L. Xie, F. Fang, B. Sun, M. Chen, and Z. Zhang, “Wavelength Switchable Mode-Locked Fiber Laser With Tapered Two-Mode Fiber,” IEEE Photonics J. 11(5), 1–8 (2019). [CrossRef]  

22. F. Fang, B. Sun, Z. Zhang, J. Xu, and L. Zhang, “Improvement on refractive index sensing by exploiting the tapered two-mode fibers,” Chin. Opt. Lett. 17(11), 110604 (2019). [CrossRef]  

23. S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016). [CrossRef]  

24. L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018). [CrossRef]  

25. C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017). [CrossRef]  

26. M. Deng, L. Liu, Y. Zhao, G. Yin, and T. Zhu, “Highly sensitive temperature sensor based on an ultra-compact Mach-Zehnder interferometer with side-opened channels,” Opt. Lett. 42(18), 3549–3552 (2017). [CrossRef]  

27. L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015). [CrossRef]  

28. Z. Xu, X. Shu, and H. Fu, “Sensitivity enhanced fiber sensor based on a fiber ring microwave photonic filter with the Vernier effect,” Opt. Express 25(18), 21559–21566 (2017). [CrossRef]  

29. B. Wu, L. Chen, C. Zhao, and C. C. Chan, “Polypyrrole-Coated Polarization Maintaining Fiber-Based Vernier Effect for Isopropanol Measurement,” J. Lightwave Technol. 37(11), 2768–2772 (2019). [CrossRef]  

30. A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020). [CrossRef]  

31. M. Xie, H. Gong, J. Zhang, C. L. Zhao, and X. Dong, “Vernier effect of two cascaded in-fiber Mach-Zehnder interferometers based on a spherical-shaped structure,” Appl. Opt. 58(23), 6204–6210 (2019). [CrossRef]  

32. G. Zuo, W. Li, Z. Yang, S. Li, R. Qi, Y. Huang, and L. Xia, “Double Phase Matching in MZI With Antiresonant Effect for Optical Fiber Sensor Application,” J. Lightwave Technol. 39(2), 660–666 (2021). [CrossRef]  

33. S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021). [CrossRef]  

34. M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

35. Y. Xue, Y.-S. Yu, R. Yang, C. Wang, C. Chen, J.-C. Guo, X.-Y. Zhang, C.-C. Zhu, and H.-B. Sun, “Ultrasensitive temperature sensor based on an isopropanol-sealed optical microfiber taper,” Opt. Lett. 38(8), 1209–1211 (2013). [CrossRef]  

36. Y. Ren, X. Liu, X. Zhang, and J. Yang, “Two-mode fiber based directional torsion sensor with intensity modulation and 0 degrees turning point,” Opt. Express 27(20), 29340–29349 (2019). [CrossRef]  

37. X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018). [CrossRef]  

38. G. Yin, C. Wang, Y. Zhao, B. Jiang, T. Zhu, Y. Wang, and L. Zhang, “Multi-channel mode converter based on a modal interferometer in a two-mode fiber,” Opt. Lett. 42(19), 3757–3760 (2017). [CrossRef]  

39. C. He, J. Fang, Y. Zhang, Y. Yang, J. Yu, J. Zhang, H. Guan, W. Qiu, P. Wu, J. Dong, H. Lu, J. Tang, W. Zhu, N. Arsad, Y. Xiao, and Z. Chen, “High performance all-fiber temperature sensor based on coreless side-polished fiber wrapped with polydimethylsiloxane,” Opt. Express 26(8), 9686–9699 (2018). [CrossRef]  

40. M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016). [CrossRef]  

41. D. Guo, L. Wu, H. Yu, A. Zhou, Q. Li, F. Mumtaz, C. Du, and W. Hu, “Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement,” Appl. Opt. 59(13), 3927–3932 (2020). [CrossRef]  

42. H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019). [CrossRef]  

References

  • View by:

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    [Crossref]
  2. S. Pevec and D. Donlagic, “High resolution, all-fiber, micro-machined sensor for simultaneous measurement of refractive index and temperature,” Opt. Express 22(13), 16241–16253 (2014).
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  3. Z. Zhu, L. Liu, Z. Liu, Y. Zhang, and Y. Zhang, “Surface-plasmon-resonance-based optical-fiber temperature sensor with high sensitivity and high figure of merit,” Opt. Lett. 42(15), 2948–2951 (2017).
    [Crossref]
  4. J. Dong, K. S. Chiang, and W. Jin, “Compact Three-Dimensional Polymer Waveguide Mode Multiplexer,” J. Lightwave Technol. 33(22), 4580–4588 (2015).
    [Crossref]
  5. W. Jin and K. S. Chiang, “Reconfigurable Three-Mode Converter Based On Cascaded Electro-Optic Long-Period Gratings,” IEEE J. Sel. Top. Quantum Electron. 26(5), 1–6 (2020).
    [Crossref]
  6. J. Dong and K. S. Chiang, “Temperature-Insensitive Mode Converters With CO2-Laser Written Long-Period Fiber Gratings,” IEEE Photonics Technol. Lett. 27(9), 1006–1009 (2015).
    [Crossref]
  7. G. Labroille, B. Denolle, P. Jian, P. Genevaux, N. Treps, and J. F. Morizur, “Efficient and mode selective spatial mode multiplexer based on multi-plane light conversion,” Opt. Express 22(13), 15599–15607 (2014).
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  8. Q. Huang, W. Jin, and K. S. Chiang, “Broadband mode switch based on a three-dimensional waveguide Mach-Zehnder interferometer,” Opt. Lett. 42(23), 4877–4880 (2017).
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  9. C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
    [Crossref]
  10. A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
    [Crossref]
  11. S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
    [Crossref]
  12. X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
    [Crossref]
  13. U. Sampath, D. Kim, H. Kim, and M. Song, “Polymer-coated FBG sensor for simultaneous temperature and strain monitoring in composite materials under cryogenic conditions,” Appl. Opt. 57(3), 492–497 (2018).
    [Crossref]
  14. P. F. Wang, G. Brambilla, M. Ding, Y. Semenova, Q. Wu, and G. Farrell, “High-sensitivity, evanescent field refractometric sensor based on a tapered, multimode fiber interference,” Opt. Lett. 36(12), 2233–2235 (2011).
    [Crossref]
  15. M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
    [Crossref]
  16. A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
    [Crossref]
  17. Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
    [Crossref]
  18. B. Sun, F. Fang, Z. Zhang, J. Xu, and L. Zhang, “High-sensitivity and low-temperature magnetic field sensor based on tapered two-mode fiber interference,” Opt. Lett. 43(6), 1311–1314 (2018).
    [Crossref]
  19. B. Sun and Y. Wang, “High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers,” Micromachines 11(3), 270 (2020).
    [Crossref]
  20. L. Xie, B. Sun, M. Chen, and Z. Zhang, “Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect,” Opt. Express 28(22), 32447–32455 (2020).
    [Crossref]
  21. L. Xie, F. Fang, B. Sun, M. Chen, and Z. Zhang, “Wavelength Switchable Mode-Locked Fiber Laser With Tapered Two-Mode Fiber,” IEEE Photonics J. 11(5), 1–8 (2019).
    [Crossref]
  22. F. Fang, B. Sun, Z. Zhang, J. Xu, and L. Zhang, “Improvement on refractive index sensing by exploiting the tapered two-mode fibers,” Chin. Opt. Lett. 17(11), 110604 (2019).
    [Crossref]
  23. S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
    [Crossref]
  24. L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
    [Crossref]
  25. C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
    [Crossref]
  26. M. Deng, L. Liu, Y. Zhao, G. Yin, and T. Zhu, “Highly sensitive temperature sensor based on an ultra-compact Mach-Zehnder interferometer with side-opened channels,” Opt. Lett. 42(18), 3549–3552 (2017).
    [Crossref]
  27. L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
    [Crossref]
  28. Z. Xu, X. Shu, and H. Fu, “Sensitivity enhanced fiber sensor based on a fiber ring microwave photonic filter with the Vernier effect,” Opt. Express 25(18), 21559–21566 (2017).
    [Crossref]
  29. B. Wu, L. Chen, C. Zhao, and C. C. Chan, “Polypyrrole-Coated Polarization Maintaining Fiber-Based Vernier Effect for Isopropanol Measurement,” J. Lightwave Technol. 37(11), 2768–2772 (2019).
    [Crossref]
  30. A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
    [Crossref]
  31. M. Xie, H. Gong, J. Zhang, C. L. Zhao, and X. Dong, “Vernier effect of two cascaded in-fiber Mach-Zehnder interferometers based on a spherical-shaped structure,” Appl. Opt. 58(23), 6204–6210 (2019).
    [Crossref]
  32. G. Zuo, W. Li, Z. Yang, S. Li, R. Qi, Y. Huang, and L. Xia, “Double Phase Matching in MZI With Antiresonant Effect for Optical Fiber Sensor Application,” J. Lightwave Technol. 39(2), 660–666 (2021).
    [Crossref]
  33. S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
    [Crossref]
  34. M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).
  35. Y. Xue, Y.-S. Yu, R. Yang, C. Wang, C. Chen, J.-C. Guo, X.-Y. Zhang, C.-C. Zhu, and H.-B. Sun, “Ultrasensitive temperature sensor based on an isopropanol-sealed optical microfiber taper,” Opt. Lett. 38(8), 1209–1211 (2013).
    [Crossref]
  36. Y. Ren, X. Liu, X. Zhang, and J. Yang, “Two-mode fiber based directional torsion sensor with intensity modulation and 0 degrees turning point,” Opt. Express 27(20), 29340–29349 (2019).
    [Crossref]
  37. X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
    [Crossref]
  38. G. Yin, C. Wang, Y. Zhao, B. Jiang, T. Zhu, Y. Wang, and L. Zhang, “Multi-channel mode converter based on a modal interferometer in a two-mode fiber,” Opt. Lett. 42(19), 3757–3760 (2017).
    [Crossref]
  39. C. He, J. Fang, Y. Zhang, Y. Yang, J. Yu, J. Zhang, H. Guan, W. Qiu, P. Wu, J. Dong, H. Lu, J. Tang, W. Zhu, N. Arsad, Y. Xiao, and Z. Chen, “High performance all-fiber temperature sensor based on coreless side-polished fiber wrapped with polydimethylsiloxane,” Opt. Express 26(8), 9686–9699 (2018).
    [Crossref]
  40. M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
    [Crossref]
  41. D. Guo, L. Wu, H. Yu, A. Zhou, Q. Li, F. Mumtaz, C. Du, and W. Hu, “Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement,” Appl. Opt. 59(13), 3927–3932 (2020).
    [Crossref]
  42. H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
    [Crossref]

2021 (2)

G. Zuo, W. Li, Z. Yang, S. Li, R. Qi, Y. Huang, and L. Xia, “Double Phase Matching in MZI With Antiresonant Effect for Optical Fiber Sensor Application,” J. Lightwave Technol. 39(2), 660–666 (2021).
[Crossref]

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

2020 (6)

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

W. Jin and K. S. Chiang, “Reconfigurable Three-Mode Converter Based On Cascaded Electro-Optic Long-Period Gratings,” IEEE J. Sel. Top. Quantum Electron. 26(5), 1–6 (2020).
[Crossref]

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

B. Sun and Y. Wang, “High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers,” Micromachines 11(3), 270 (2020).
[Crossref]

L. Xie, B. Sun, M. Chen, and Z. Zhang, “Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect,” Opt. Express 28(22), 32447–32455 (2020).
[Crossref]

D. Guo, L. Wu, H. Yu, A. Zhou, Q. Li, F. Mumtaz, C. Du, and W. Hu, “Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement,” Appl. Opt. 59(13), 3927–3932 (2020).
[Crossref]

2019 (9)

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

B. Wu, L. Chen, C. Zhao, and C. C. Chan, “Polypyrrole-Coated Polarization Maintaining Fiber-Based Vernier Effect for Isopropanol Measurement,” J. Lightwave Technol. 37(11), 2768–2772 (2019).
[Crossref]

L. Xie, F. Fang, B. Sun, M. Chen, and Z. Zhang, “Wavelength Switchable Mode-Locked Fiber Laser With Tapered Two-Mode Fiber,” IEEE Photonics J. 11(5), 1–8 (2019).
[Crossref]

F. Fang, B. Sun, Z. Zhang, J. Xu, and L. Zhang, “Improvement on refractive index sensing by exploiting the tapered two-mode fibers,” Chin. Opt. Lett. 17(11), 110604 (2019).
[Crossref]

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

M. Xie, H. Gong, J. Zhang, C. L. Zhao, and X. Dong, “Vernier effect of two cascaded in-fiber Mach-Zehnder interferometers based on a spherical-shaped structure,” Appl. Opt. 58(23), 6204–6210 (2019).
[Crossref]

Y. Ren, X. Liu, X. Zhang, and J. Yang, “Two-mode fiber based directional torsion sensor with intensity modulation and 0 degrees turning point,” Opt. Express 27(20), 29340–29349 (2019).
[Crossref]

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

2018 (7)

B. Sun, F. Fang, Z. Zhang, J. Xu, and L. Zhang, “High-sensitivity and low-temperature magnetic field sensor based on tapered two-mode fiber interference,” Opt. Lett. 43(6), 1311–1314 (2018).
[Crossref]

L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
[Crossref]

X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
[Crossref]

C. He, J. Fang, Y. Zhang, Y. Yang, J. Yu, J. Zhang, H. Guan, W. Qiu, P. Wu, J. Dong, H. Lu, J. Tang, W. Zhu, N. Arsad, Y. Xiao, and Z. Chen, “High performance all-fiber temperature sensor based on coreless side-polished fiber wrapped with polydimethylsiloxane,” Opt. Express 26(8), 9686–9699 (2018).
[Crossref]

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
[Crossref]

U. Sampath, D. Kim, H. Kim, and M. Song, “Polymer-coated FBG sensor for simultaneous temperature and strain monitoring in composite materials under cryogenic conditions,” Appl. Opt. 57(3), 492–497 (2018).
[Crossref]

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

2017 (6)

2016 (2)

M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
[Crossref]

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

2015 (3)

J. Dong, K. S. Chiang, and W. Jin, “Compact Three-Dimensional Polymer Waveguide Mode Multiplexer,” J. Lightwave Technol. 33(22), 4580–4588 (2015).
[Crossref]

J. Dong and K. S. Chiang, “Temperature-Insensitive Mode Converters With CO2-Laser Written Long-Period Fiber Gratings,” IEEE Photonics Technol. Lett. 27(9), 1006–1009 (2015).
[Crossref]

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

2014 (3)

2013 (2)

S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
[Crossref]

Y. Xue, Y.-S. Yu, R. Yang, C. Wang, C. Chen, J.-C. Guo, X.-Y. Zhang, C.-C. Zhu, and H.-B. Sun, “Ultrasensitive temperature sensor based on an isopropanol-sealed optical microfiber taper,” Opt. Lett. 38(8), 1209–1211 (2013).
[Crossref]

2011 (1)

Arsad, N.

Aruna Gandhi, M. S.

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Bartelt, H.

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

Bierlich, J.

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

Brambilla, G.

Chan, C. C.

B. Wu, L. Chen, C. Zhao, and C. C. Chan, “Polypyrrole-Coated Polarization Maintaining Fiber-Based Vernier Effect for Isopropanol Measurement,” J. Lightwave Technol. 37(11), 2768–2772 (2019).
[Crossref]

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Chen, L.

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L. Xie, B. Sun, M. Chen, and Z. Zhang, “Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect,” Opt. Express 28(22), 32447–32455 (2020).
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M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
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L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
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Deming, L.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
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C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
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X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
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S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
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Donlagic, D.

Du, C.

D. Guo, L. Wu, H. Yu, A. Zhou, Q. Li, F. Mumtaz, C. Du, and W. Hu, “Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement,” Appl. Opt. 59(13), 3927–3932 (2020).
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C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
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Du, H.

X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
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Duan, J.

X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
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M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
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Fang, J.

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Ferreira, M. S.

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
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A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
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A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
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A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
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Fu, H. Y.

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Gao, X.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
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Gomes, A. D.

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

Gong, H.

Guan, H.

Guo, D.

Guo, J.-C.

Haipeng, L.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Han, F.

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
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He, C.

Hernandez-Romano, I.

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
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Hu, W.

Huang, Q.

Huang, Y.

Hwang, J.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
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Jiang, B.

Jin, W.

Kang, J.

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

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Kim, H.

Kim, J.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

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A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

Kumar, A.

M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
[Crossref]

Kumar, M.

M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
[Crossref]

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Le, A. D. D.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

Li, D.

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

Li, J.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
[Crossref]

Li, Q.

D. Guo, L. Wu, H. Yu, A. Zhou, Q. Li, F. Mumtaz, C. Du, and W. Hu, “Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement,” Appl. Opt. 59(13), 3927–3932 (2020).
[Crossref]

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Li, S.

Li, T.

S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
[Crossref]

Li, W.

Li, Y.

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

Lin, H.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Lin, Z.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Liu, L.

Liu, S.

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

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Y. Ren, X. Liu, X. Zhang, and J. Yang, “Two-mode fiber based directional torsion sensor with intensity modulation and 0 degrees turning point,” Opt. Express 27(20), 29340–29349 (2019).
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M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Liu, Z.

Lu, H.

Lu, S.

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Luo, B.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Luo, Y.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Ma, K.

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

Mao, B.

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

Marrujo-Garcia, S.

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

May-Arrioja, D. A.

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

Minkovich, V. P.

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

Morizur, J. F.

Mu, X.

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Mumtaz, F.

Ning, T.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Pan, W.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Park, K. H.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

Park, S.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

Pei, L.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Peng, Y.

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
[Crossref]

Pevec, S.

Qi, R.

Qiu, W.

Qizhen, S.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Ren, Y.

Ren, Z.

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

Rothhardt, M.

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

Sampath, U.

Semenova, Y.

Shao, L. Y.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Shen, C.

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

Shu, X.

Shum, P. P.

S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
[Crossref]

Song, M.

Su, H.

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

Sun, B.

Sun, H.-B.

Sun, X.

X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
[Crossref]

Tang, J.

Tong, R. J.

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
[Crossref]

Torres-Cisneros, M.

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

Treps, N.

Wang, C.

Wang, J.

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
[Crossref]

Wang, M.

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

Wang, P. F.

Wang, Q.

C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
[Crossref]

Wang, R.

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
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Wang, T.

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
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B. Sun and Y. Wang, “High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers,” Micromachines 11(3), 270 (2020).
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S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Wu, B.

Wu, L.

Wu, P.

Wu, Q.

Xia, F.

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
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Xia, L.

Xiao, Y.

Xiaohui, S.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Xie, L.

L. Xie, B. Sun, M. Chen, and Z. Zhang, “Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect,” Opt. Express 28(22), 32447–32455 (2020).
[Crossref]

L. Xie, F. Fang, B. Sun, M. Chen, and Z. Zhang, “Wavelength Switchable Mode-Locked Fiber Laser With Tapered Two-Mode Fiber,” IEEE Photonics J. 11(5), 1–8 (2019).
[Crossref]

Xie, M.

Xu, J.

Xu, Z.

Xue, L.

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
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Xue, Y.

Yan, L.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Yang, J.

Yang, L.

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
[Crossref]

Yang, R.

Yang, Y.

Yang, Z.

Yin, G.

You, H.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Yu, H.

Yu, J.

Yu, Y.-S.

Yusuf, M.

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

Zhang, C.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Zhang, J.

Zhang, L.

Zhang, Q.

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
[Crossref]

Zhang, S.

S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
[Crossref]

Zhang, X.

Zhang, X.-Y.

Zhang, Y.

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

C. He, J. Fang, Y. Zhang, Y. Yang, J. Yu, J. Zhang, H. Guan, W. Qiu, P. Wu, J. Dong, H. Lu, J. Tang, W. Zhu, N. Arsad, Y. Xiao, and Z. Chen, “High performance all-fiber temperature sensor based on coreless side-polished fiber wrapped with polydimethylsiloxane,” Opt. Express 26(8), 9686–9699 (2018).
[Crossref]

L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
[Crossref]

Z. Zhu, L. Liu, Z. Liu, Y. Zhang, and Y. Zhang, “Surface-plasmon-resonance-based optical-fiber temperature sensor with high sensitivity and high figure of merit,” Opt. Lett. 42(15), 2948–2951 (2017).
[Crossref]

Z. Zhu, L. Liu, Z. Liu, Y. Zhang, and Y. Zhang, “Surface-plasmon-resonance-based optical-fiber temperature sensor with high sensitivity and high figure of merit,” Opt. Lett. 42(15), 2948–2951 (2017).
[Crossref]

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
[Crossref]

Zhang, Z.

Zhao, C.

B. Wu, L. Chen, C. Zhao, and C. C. Chan, “Polypyrrole-Coated Polarization Maintaining Fiber-Based Vernier Effect for Isopropanol Measurement,” J. Lightwave Technol. 37(11), 2768–2772 (2019).
[Crossref]

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

Zhao, C. L.

Zhao, L.

L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
[Crossref]

Zhao, Y.

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
[Crossref]

M. Deng, L. Liu, Y. Zhao, G. Yin, and T. Zhu, “Highly sensitive temperature sensor based on an ultra-compact Mach-Zehnder interferometer with side-opened channels,” Opt. Lett. 42(18), 3549–3552 (2017).
[Crossref]

C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
[Crossref]

G. Yin, C. Wang, Y. Zhao, B. Jiang, T. Zhu, Y. Wang, and L. Zhang, “Multi-channel mode converter based on a modal interferometer in a two-mode fiber,” Opt. Lett. 42(19), 3757–3760 (2017).
[Crossref]

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Zheng, J.

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Zhilin, X.

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

Zhou, A.

Zhu, B.

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
[Crossref]

Zhu, C.-C.

Zhu, J.

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

Zhu, T.

Zhu, W.

Zhu, Z.

Zou, X.

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

Zuo, G.

Appl. Opt. (3)

Appl. Phys. Lett. (1)

L. Zhao, Y. Zhang, J. Wang, and Y. Chen, “Highly sensitive temperature sensor based on an isopropanol-sealed optical microfiber coupler,” Appl. Phys. Lett. 113(11), 111901–1211 (2018).
[Crossref]

Chin. Opt. Lett. (1)

IEEE J. Sel. Top. Quantum Electron. (1)

W. Jin and K. S. Chiang, “Reconfigurable Three-Mode Converter Based On Cascaded Electro-Optic Long-Period Gratings,” IEEE J. Sel. Top. Quantum Electron. 26(5), 1–6 (2020).
[Crossref]

IEEE Photonics J. (1)

L. Xie, F. Fang, B. Sun, M. Chen, and Z. Zhang, “Wavelength Switchable Mode-Locked Fiber Laser With Tapered Two-Mode Fiber,” IEEE Photonics J. 11(5), 1–8 (2019).
[Crossref]

IEEE Photonics Technol. Lett. (2)

J. Dong and K. S. Chiang, “Temperature-Insensitive Mode Converters With CO2-Laser Written Long-Period Fiber Gratings,” IEEE Photonics Technol. Lett. 27(9), 1006–1009 (2015).
[Crossref]

S. Qizhen, S. Xiaohui, J. Weihua, X. Zhilin, L. Haipeng, L. Deming, and Z. Lin, “Graphene-Assisted Microfiber for Optical-Power-Based Temperature Sensor,” IEEE Photonics Technol. Lett. 28(4), 383–386 (2016).
[Crossref]

IEEE Sens. J. (2)

Y. Zhang, L. Xue, T. Wang, L. Yang, B. Zhu, and Q. Zhang, “High Performance Temperature Sensing of Single Mode-Multimode-Single Mode Fiber With Thermo-Optic Polymer as Cladding of Multimode Fiber Segment,” IEEE Sens. J. 14(4), 1143–1147 (2014).
[Crossref]

C. Zhao, F. Han, Y. Li, B. Mao, J. Kang, C. Shen, and X. Dong, “Volatile Organic Compound Sensor Based on PDMS Coated Fabry–Perot Interferometer With Vernier Effect,” IEEE Sens. J. 19(12), 4443–4450 (2019).
[Crossref]

J. Lightwave Technol. (3)

Materials (1)

X. Dong, H. Du, X. Sun, and J. Duan, “Simultaneous Strain and Temperature Sensor Based on a Fiber Mach-Zehnder Interferometer Coated with Pt by Iron Sputtering Technology,” Materials 11(9), 1535 (2018).
[Crossref]

Micromachines (1)

B. Sun and Y. Wang, “High-Sensitivity Detection of IgG Operating near the Dispersion Turning Point in Tapered Two-Mode Fibers,” Micromachines 11(3), 270 (2020).
[Crossref]

Opt. Commun. (3)

L. Y. Shao, Y. Luo, Z. Zhang, X. Zou, B. Luo, W. Pan, and L. Yan, “Sensitivity-enhanced temperature sensor with cascaded fiber optic Sagnac interferometers based on Vernier-effect,” Opt. Commun. 336, 73–76 (2015).
[Crossref]

S. Zhang, X. Dong, T. Li, C. C. Chan, and P. P. Shum, “Simultaneous measurement of relative humidity and temperature with PCF-MZI cascaded by fiber Bragg grating,” Opt. Commun. 303, 42–45 (2013).
[Crossref]

X. Gao, T. Ning, C. Zhang, J. Xu, J. Zheng, H. Lin, J. Li, L. Pei, and H. You, “A dual-parameter fiber sensor based on few-mode fiber and fiber Bragg grating for strain and temperature sensing,” Opt. Commun. 454, 124441 (2020).
[Crossref]

Opt. Express (6)

Opt. Fiber Technol. (2)

H. Su, Y. Zhang, Y. Zhao, K. Ma, and J. Wang, “Isopropanol-sealed multimode microfiber for temperature sensing,” Opt. Fiber Technol. 51, 1–5 (2019).
[Crossref]

C. Du, Q. Wang, Y. Zhao, and J. Li, “Highly sensitive temperature sensor based on an isopropanol-filled photonic crystal fiber long period grating,” Opt. Fiber Technol. 34, 12–15 (2017).
[Crossref]

Opt. Laser Technol. (1)

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazão, “Hollow microsphere combined with optical harmonic Vernier effect for strain and temperature discrimination,” Opt. Laser Technol. 127, 106198 (2020).
[Crossref]

Opt. Lett. (7)

M. Deng, L. Liu, Y. Zhao, G. Yin, and T. Zhu, “Highly sensitive temperature sensor based on an ultra-compact Mach-Zehnder interferometer with side-opened channels,” Opt. Lett. 42(18), 3549–3552 (2017).
[Crossref]

B. Sun, F. Fang, Z. Zhang, J. Xu, and L. Zhang, “High-sensitivity and low-temperature magnetic field sensor based on tapered two-mode fiber interference,” Opt. Lett. 43(6), 1311–1314 (2018).
[Crossref]

Q. Huang, W. Jin, and K. S. Chiang, “Broadband mode switch based on a three-dimensional waveguide Mach-Zehnder interferometer,” Opt. Lett. 42(23), 4877–4880 (2017).
[Crossref]

Z. Zhu, L. Liu, Z. Liu, Y. Zhang, and Y. Zhang, “Surface-plasmon-resonance-based optical-fiber temperature sensor with high sensitivity and high figure of merit,” Opt. Lett. 42(15), 2948–2951 (2017).
[Crossref]

P. F. Wang, G. Brambilla, M. Ding, Y. Semenova, Q. Wu, and G. Farrell, “High-sensitivity, evanescent field refractometric sensor based on a tapered, multimode fiber interference,” Opt. Lett. 36(12), 2233–2235 (2011).
[Crossref]

G. Yin, C. Wang, Y. Zhao, B. Jiang, T. Zhu, Y. Wang, and L. Zhang, “Multi-channel mode converter based on a modal interferometer in a two-mode fiber,” Opt. Lett. 42(19), 3757–3760 (2017).
[Crossref]

Y. Xue, Y.-S. Yu, R. Yang, C. Wang, C. Chen, J.-C. Guo, X.-Y. Zhang, C.-C. Zhu, and H.-B. Sun, “Ultrasensitive temperature sensor based on an isopropanol-sealed optical microfiber taper,” Opt. Lett. 38(8), 1209–1211 (2013).
[Crossref]

Opt. Quantum Electron. (1)

M. Wang, D. Li, R. Wang, J. Zhu, and Z. Ren, “PDMS-assisted graphene microfiber ring resonator for temperature sensor,” Opt. Quantum Electron. 50(3), 1–8 (2018).
[Crossref]

Sens. Actuators, A (1)

M. Q. Chen, Y. Zhao, F. Xia, Y. Peng, and R. J. Tong, “High sensitivity temperature sensor based on fiber air-microbubble Fabry-Perot interferometer with PDMS-filled hollow-core fiber,” Sens. Actuators, A 275, 60–66 (2018).
[Crossref]

Sens. Actuators, B (2)

A. D. D. Le, J. Hwang, M. Yusuf, K. H. Park, S. Park, and J. Kim, “Simultaneous Measurement of Humidity and Temperature with Cytop-reduced Graphene Oxide-overlaid Two-mode Optical Fiber Sensor,” Sens. Actuators, B 298, 126841 (2019).
[Crossref]

M. Kumar, A. Kumar, and R. Dwivedi, “Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference,” Sens. Actuators, B 222, 556–561 (2016).
[Crossref]

Sensors (2)

A. D. Gomes, M. S. Ferreira, J. Bierlich, J. Kobelke, M. Rothhardt, H. Bartelt, and O. Frazao, “Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fibre Sensors,” Sensors 19(24), 5431–5438 (2019).
[Crossref]

S. Marrujo-Garcia, I. Hernandez-Romano, D. A. May-Arrioja, V. P. Minkovich, and M. Torres-Cisneros, “In-Line Mach-Zehnder Interferometers Based on a Capillary Hollow-Core Fiber Using Vernier Effect for a Highly Sensitive Temperature Sensor,” Sensors 21(16), 5471 (2021).
[Crossref]

Other (1)

M. Dai, Z. Chen, Y. Zhao, X. Mu, X. Liu, M. S. Aruna Gandhi, Q. Li, S. Lu, S. Liu, and H. Y. Fu, “Fiber optic temperature sensor with online controllable sensitivity based on Vernier effect,” IEEE Sens. J. (to be published).

Data availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

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Figures (13)

Fig. 1.
Fig. 1. Schematic of the proposed isopropanol-sealed modal interferometer.
Fig. 2.
Fig. 2. (a)-(d) Schematic diagram of the device fabrication process. (e) The microscope image of the TTMF with a uniform waist.
Fig. 3.
Fig. 3. Transmission spectra of the modal interferometer in air and in isopropanol.
Fig. 4.
Fig. 4. Calculated transmission spectra of the modal interference under various temperatures.
Fig. 5.
Fig. 5. Schematic of the experimental setup for temperature tests.
Fig. 6.
Fig. 6. The measured transmission spectra for modal interferometer without isopropanol at different temperatures.
Fig. 7.
Fig. 7. The measured transmission spectra for modal interferometer sealed with isopropanol at different temperatures in the wavelength range (a)1300-1380 nm and (b) 1600-1680 nm.
Fig. 8.
Fig. 8. (a) Averaged FSR in 1300-1700 nm of the interference spectrum of the modal interferometer as a function temperature, (b) FSR (at 30 °C) of the interference spectrum of the modal interferometer as a function wavelength.
Fig. 9.
Fig. 9. Measured spectra of the temperature sensor with Vernier-like effect for temperatures (a) from 28 °C to 32 °C, (b) from 33 °C to 37 °C, (c) from 45 °C to 49 °C, (d) from 53 °C to 57 °C.
Fig. 10.
Fig. 10. Linear fitting of wavelength shift versus temperature for the temperature sensor with Vernier-like effect.
Fig. 11.
Fig. 11. Schematic of the experimental setup for measuring the near-field output patterns.
Fig. 12.
Fig. 12. Near-field patterns at the dips and peaks of the interference spectrum under 26 °C.
Fig. 13.
Fig. 13. Output mode patterns at 1546 nm with different temperatures.

Tables (1)

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Table 1. Sensitivity comparison with other temperature sensing structures and materials.

Equations (5)

Equations on this page are rendered with MathJax. Learn more.

I = I 1 + I 2 + 2 I 1 I 2 cos ( Δ φ )
Δ φ = 2 π Δ n e f f L λ
F S R = λ 2 Δ n e f f L
S = d λ d n e x t = λ 1 Γ ( 1 Δ n e f f d Δ n e f f d n e x t )
M = S e n v e l o p e S

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