Abstract

A novel refractive index sensor based on etched multicore fiber Bragg gratings with temperature in-line compensation is proposed and experimentally demonstrated. By chemically etching the cladding of the multicore fiber, the six outer cores exhibit the sensitive responses to the surrounding refractive index change, with refractive index insensitive and temperature-sensitive central core inside of the multicore fiber. By using the a central Bragg wavelength in the multicore fiber as temperature compensators, the refractive index sensing can be in-line compensated. Moreover, the distribution of multiple outer cores enables the capability of avoiding the nonhomogeneous performance by averaging and balancing the read-out data. Theoretical analysis and experimental results demonstrate that this structure can easily discriminate the RI and temperature. The maximum sensitivity 42.83 nm/ RIU could be obtained at around 1.435 RIU, and the temperature sensitivity is 9.89 pm/°C. The proposed structure is able to in-line and in-situ determine refractive index and temperature simultaneously.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

It is well known that fiber Bragg gratings (FBGs) have been utilized as optical sensors to measure a wide range of physical parameters including temperature, pressure, loading, bending, strain, etc. [14]. The conventional FBGs is not sensitive to the surrounding refractive index (SRI) due to its intrinsic coupling mode. However, it has been found that FBGs can achieve a considerable sensitivity to refractive index (RI) by heating-and-tapering [5], side-polishing [6], or chemical etching [7]. Comparatively, chemical etching is appealing for producing relatively robust and stable fiber devices with reduced size in a convenient way. A lot of research works have been conducted to achieve RI sensitive FBGs with the chemical etching technique. For examples, Iadicicco et al. [8] has demonstrated a thinned FBG sensor, which can achieve RI sensitivity based on intensity measurements. Chen et al. [9] has studied the cladding mode resonances of a chemical etch-eroded fiber Bragg grating for ambient RI sensing. Zhou et al. [10] has measured the concentrations of sugar solution by an etched tilted Bragg grating structures in multimode fiber. J. H. Osório et al [11] exposed the surface-core with FBGs to the external environment, and achieved a maximum RI sensitivity of ∼40 nm/RIU. However, these previous works are mainly focused on RI sensing. Noticeably, the temperature effect should not be neglected to trace an accurate RI value, and the RI value is even dependent on temperature. Simultaneous sensing of refractive index and temperature have been reported using sampled FBG, dual long period gratings (LPGs), modified FBGs, hybrid LPG-FBG structures, F-P cavity, and Mach–Zehnder interferometer [1217].

Recently, multicore fiber (MCF) have shown great potential for sensing applications, including strain [18], curvature [19], temperature [20], and shape sensing [21]. Additionally, the multicore fiber can also be used for RI sensing. Zhou proposed a Michelson interferometer composed of an asymmetrical twin-core fiber. By properly splicing this twin-core fiber to a single-mode fiber (SMF), a Michelson interferometer is realized with a sensitivity of 826.8 nm/RIU [22]. Daniel demonstrated a highly sensitive RI sensing structure based on multicore coupled structures [23]. These sensors proposed by the peers have high RI sensitivity, but they are easy to be influenced by the temperature or strain-crosstalk. On the other hand, eched MCF can be employed to consititute cascaded structure for temperature sensing, which exhibits a single parameter sensitivity [24].

In this work, a RI sensor based on etched Fiber Bragg Gratings in multicore fibers (eFBG-MCFs) with temperature in-line compensation is proposed and experimentally demonstrated. Different from the conventional etched FBG in SMF, this multicore structure contains six outer cores and one central core, which locate at the same position along longitudinal direction. After HF-etching, the cladding of MCF was partly removed, the wavelength shifts of FBGs in six outer cores exhibit the sensitive responses to the SRI change, with an RI-insensitive and temperature-sensitive central core inside of the MCF. The wavelength shift of FBGs in outer cores is used to determine SRI, while the wavelength shift of FBG in central core is employed to compensate for temperature variation. The following experiment demonstrates that this simple structure can easily discriminate the RI and temperature.

2. Principles and simulation

The principle of the etched MCF sensor can be drawn by extending the coupled mode theory to the specific grating structure. The MCF (YOFC, China) contains seven Ge-doped cores surrounded by trench was adopted. The MCF diameter is 150.0 µm, the pitch size is 41.5 µm, and the trench and core diameter are 24.0 µm and 8.2 µm, respectively. The six outer cores are symmetrically surrounding the central core. Here, the cladding of the MCF is controllably removed by means of wet chemical etching. If the cladding diameter is uniformly reduced, it can be presumed the six outer cores are at same condition. So the Bragg wavelength of different cores can be given by

$${\lambda _C} = 2{n_{eff,C}} \cdot \Lambda $$
$${\lambda_O} = 2{n_{eff,O}} \cdot \Lambda $$
where ${\lambda _C}$ and ${\lambda _O}$ are the Bragg wavelengths of the central core and outer core, respectively, with a grating pitch of Λ. ${n_{eff,C}}$ and ${n_{eff,O}}$ are their effective refractive indexes. By immersing the optical fiber without coating layer in an etching liquid, the cladding is etched gradually, and consequently the surrounding is close to the outer cores. In this case, the weakly guiding approximation is still applicable to the central core grating. As for the outer core grating, the light is coupled out of the core into cladding, so the FBGs in outer cores are sensitive to SRI [25]. To further understand the interaction between the etched fiber and the surrounding environment, numerical simulations in COMSOL Multiphysics were performed for a structure with the following simulation parameters: ncladding=1.444, ntrench=1.442, and ncore=1.448. Firstly, the cladding diameter is reduced from 150 µm to 80 µm, and the SRI is fixed at 1.333 to study the relationship between effective RI and the cladding diameter.

Figure 1 shows the electrical-field (e-field) distributions with different cladding diameters. For COMSOL simulations, the simulated distribtions are obtained by specifying the two types of modes, center-core mode and outer-core mode. Hence, the e-field distributions of center-core mode (a-d) and outer-core mode (e-h) are shown respectively. It can be found that the center-core mode maintains almost same, while the outer-core modes change with the decrease of cladding diameter. Firstly, the e-fields distribute homegeneously in all cores, the effective RI of the outer core is as same as that of central core. Then, as the cladding diameter is reduced to be 91 µm and a part of trench is etched, the evanecent e-fields of the outer core appear obviously, and the effective RI of outers begin to decrease. The e-fields in outer cores are more sensitive to the SRI. When the cladding diameter is reduced to be 88 µm, the outer-core modes evolve to be cladding mode. Considering the complexity of the cladding mode, the etched diameter under 88 µm should be avoided according to the simulation results. Therefore, the diameter of this proposed sensor should be limited in the range of 150-88 µm.

 

Fig. 1. Simulated e-field distributions of the center-core mode with diameters of (a) 150 µm, (b) 117 µm, (c) 91 µm and (d) 88 µm, and the outer-core modes with diameters of (e) 150 µm, (f) 117 µm, (g) 91 µm and (h) 88 µm.

Download Full Size | PPT Slide | PDF

Figure 2(a) plots the simulated effective RIs of central core and one of the outer cores corresponding to different cladding diameters. It is obvious that the effective RI of the central core is stable as the cladding diameter changes, which suggests that the central core does not interact with the surrounding media within the specified cladding range. On the other hand, the effective RI of outer core is firstly stable within a cladding-diameter range of 150-117 µm, then rapidly decrease in the range of 117.0-88 µm. This means the outer core begins to interact strongly with the surrounding media when the cladding diameter is reduced to a certain value, i.e., 117 µm. When the diameter is reduced to be approximately 88 µm, the effective RI of outer core decreases very slowly. It has been figured out by the previous analysis of the simulated e-field distributions that the cladding mode is dominate for this case. Obviously, the variation of the cladding diameter within the range of 88-80 µm cannot affect the cladding mode, according to the plots in Fig. 2(a).

 

Fig. 2. (a) Effective RI of central core and one of the outer cores for different cladding diameters of MCFs (SRI=1.333). (b) Effective RI of central core and outer core for MCF diameters of 91 µm, 93 µm and 95 µm under different SRI

Download Full Size | PPT Slide | PDF

To investigate the influence of SRI on the SRI sensitivities of central and outer cores, the simulation of effective index varying trend under different SRIs is implemented. For simplification, three cladding diameters, 95 µm, 93 µm and 91 µm are focused. The SRI ranges from that of water (1.333) to the cladding (1.444). Figure 2(b) shows the simulated effective RIs corresponding to three cladding diameters under different SRIs. In the SRI range from 1.333 to 1.442 (the trench), it can be observed that the ${n_{eff,C}}$ is constant regardless of the surrounding media, which means the central core has no sensitivity to the SRI. On the other hand, the ${n_{eff,O}}$ is strongly dependent on the SRI, especially when the SRI is approching to the RI of trench (1.442). As the cladding diameter decreases, the ${n_{eff,O}}$ changes faster, which suggests that the smaller cladding diameter has a higher RI sensitivity. Obviously, ${n_{eff,C}}$ and ${n_{eff,O}}$ tend to reach the same value as the SRI approaches the RI of the trench (1.442). In the SRI range from 1.442 to 1.444 (cladding), the ${n_{eff,C}}$ and ${n_{eff,O}}$ increase fast, because the e-field of the cores couple into the cladding for bigger SRI than 1.442 RIU. As a result, the sensor has a RI sensitive range with an upper limit of 1.442 RIU. According to the simulated plots and above analysis, the effective RI of etched MCFs varies non-linearly for different SRIs. The non-linearity of the simultion implies that the RI sensitivity of FBGs in etched MCFs will be non-linear, due to the linear function between effective RI and FBG wavelength shift.

Conventional FBG is a perfect strain and temperature sensor due to its linear response, while this is not the case for RI sensing. The simulation results illustrate that when the cladding is partly removed, the outer cores are sensitive to the SRI, while the central core is not sensitive to the SRI. This feature can be consequently employed to determine RI sensing with local temperature compensation, which is the motivation of the proposed eFBG-MCFs. Assuming that the fiber is naturally stretched and not subjected to external strain, the wavelength shift of the gratings of the MCF can be expressed as follows:

$$\frac{{\Delta {\lambda _C}}}{{\lambda c}} = \left( {\frac{1}{{{n_{{e_{ff,c}}}}}} \cdot \frac{{\partial {n_{{e_{ff,C}}}}}}{{\partial T}} + \frac{1}{\Lambda } \cdot \frac{{\partial \Lambda }}{{\alpha T}}} \right)\Delta T = ({{\zeta_C} + \alpha } )\cdot \Delta T$$
$$\begin{aligned} \frac{{\Delta {\lambda _O}}}{{{\lambda _O}}} &= \left( {\frac{1}{{{n_{{e_{ff,O}}}}}} \cdot \frac{{\partial {n_{{e_{ff,O}}}}}}{{\partial T}} + \frac{1}{\Lambda } \cdot \frac{{\partial \Lambda }}{{\alpha T}}} \right)\Delta T + \left( {\frac{1}{{{n_{{e_{ff,O}}}}}} \cdot \frac{{\partial {n_{eff \cdot O}}}}{{\partial SRI}}} \right)\Delta SRI\\ &= ({{\zeta_O} + \alpha } )\cdot \Delta T + \kappa SRI \end{aligned}$$
where ${\zeta _C}$ = ${\zeta _C} = \frac{1}{{{n_{eff,C}}}} \cdot \frac{{\Delta {n_{eff,C}}}}{{\Delta T}}$ and ${\zeta _{_O}} = \frac{1}{{{n_{eff,O}}}} \cdot \frac{{\Delta {n_{eff,O}}}}{{\Delta T}}$ are the thermo-optical coefficient of the central core and outer cores of MCF, respectively. $\alpha = \frac{1}{\Lambda } \cdot \frac{{\partial \Lambda }}{{\; \partial T}}$ is the thermal expansion coefficient of the MCF, same for two kind of the grating regions. The thermo-optical coefficients of central core and outer cores, ${\zeta _C}$and ${\zeta _O}$, are slightly different, which causes the slight difference of temperature sensitivity between central core and outer cores. $\kappa = \frac{1}{{{n_{eff,O}}}} \cdot \frac{{\Delta {n_{eff,O}}}}{{\Delta SRI}}$ is the SRI coefficient of the outer core of etched MCF. Obviously, ${\lambda _C}$ is sensitive only to local temperature changes according to Eq. (3), whereas${\lambda _O}$would respond to both effects according to Eq. (4). This enables the possibility to develop a temperature-compensated RI sensor.

3. Experimental setup and fabrication

A 7-core optical fiber (YOFC, China) with seven trench-assisted cores is used in this work, with a cladding diameter of 150.0 µm and a MFD of 9.5 µm, and a pitch size of 41.5 µm. The Bragg gratings in MCF were inscribed by a conventional 193 nm excimer laser with phase mask. The reflection spectra of FBGs in MCF are shown in Fig. 3. The minor difference of the resonance wavelength among the cores is caused by the nonhomogeneous distribution of laser energy in different cores during FBG writing, which has trivial effect on the wavelength interrogation and readout for the following experiments.

 

Fig. 3. The reflection spectra of FBGs in MCF

Download Full Size | PPT Slide | PDF

The cladding of MCF was etched by immersing the MCF with inscribed FBGs in 20% HF under ambient temperature [26]. To smooth the surface of the etched area, the fiber was then transferred to a 3% HF solution and neutralized by a 2 mol/L NaOH solution after the previous etching process. The side-views and cross-sections of MCFs before and after etching are shown in Fig. 4(a-c). The trench-assisted cores are clearly observed in the cross-section pictures via the concentric circles around each core due to the refractive index difference of the trenches. It is noted that the more the MCFs cladding etched, the more hexagon-like for the cross-sections. This is attributed to the faster chemical etching speed of the trenches than that of the claddings. As shown in Fig. 4(d-f), the waists of MCFs along z-direction are smooth from a side view.

 

Fig. 4. The microscope images of cross-section for unetched MCF (a) and etched MCFs with diameters of (b) 93.2 µm, (c) 89.8 µm, and their side-views (d-f).

Download Full Size | PPT Slide | PDF

Figure 5 illustrates the experimental setup of the proposed RI sensor. As shown in the figure, an 8-channel interrogator is used to record the seven FBGs in eFBG-MCFs simultaneously via a fan-in device. The spectral responses are acquired by the 8-channel interrogator for different RI sensing tests, and also for the etching process. The insets of Fig. 5 show the schematic diagram of the probe after etching. The length of etched section is approximately 10 mm.

 

Fig. 5. Experimental setup of the proposed RI sensor and the schematic diagram of the probe.

Download Full Size | PPT Slide | PDF

Figure 6 plots the evolution of the FBG resonance wavelengths shift of different cores during etching process. It can be found that the resonance wavelengths of all cores increase during the first 100 minutes. This effect could be attributed to the continuous exothermal reaction of HF and SiO2, similar to the behavior of the previous work [27]. After etching for approximately 102 minutes, the resonance wavelengths of six outer cores (O1-O6) show an abrupt reduction, meanwhile the resonance wavelengths of central core show slightly blue shift. Hence, the stable trend of the central core ensures the possibility of temperature compensation. On the other hand, there is small diversity within approximately 0.15 nm for the wavelength shifts of the outer cores, which is attributed to the inhomogeneous etching speed of the cladding. The variation can be balanced by averaging the diverse wavelength shifts, which will contribute to diversity compensation and nonhomogeneous performance elimination during the following RI measuring.

 

Fig. 6. The evolution of the resonance wavelengths shifts of two types of cores, central core (C1) and outer cores (O1-O6)

Download Full Size | PPT Slide | PDF

After the claddings are partly removed, the interaction between the outer-core mode and the surrounding medium (HF solution) is getting stronger, and the interface is getting close to the boundary of the outer cores. The Bragg gratings of outer cores show an improved RI sensitivity due to strong coupling with higher mode, which interacts with the liquid localized in the vicinity of outer cores. Meanwhile, the Bragg grating of central core shows no sensitivity to RI. In the following experiment, the performance of the etched MCF with three diameters of 89.8 µm, 93.2 µm and 94.3 µm are investigated.

4. Results and discussions

The RI sensing experiments were conducted by immersing the fabricated sensors into an aqueous solution of glycerin at room temperature (25°C). The RIs of the solution were realized from 1.333 to 1.442 by tuning the glycerin concentration continuously. The actual RIs of the glycerin solutions were calibrated by an Abbe refractometer.

From the microscope images in Fig. 6, it is noted that the cladding etched degrees for the six outer cores of MCF are slightly different, which will cause effective RI diversity and different sensing performance of each outer core. For this sensor, the disadvantage of non-homogeneity can be overcome by using the average value of the wavelength shifts of the six outer cores (denoted by ${\bar{\textrm O}}$) to represent the general change of all of the outer cores. The distribution of six outer cores of MCF can enable the capability of averaging the nonhomogeneous performance, however, which presents particular advantage over the conventional etched SMF or other twin-core optical fiber sensors [22,2830]. In the following plots and discussions, ${\bar{\textrm O}}$ is regarded as the wavelength shift variation of outers cores under different conditions, while C represents the trend of central core.

Figure 7(a) plots the wavelength shifts as non-linear functions of the SRI for central core (C) and outer core (${\bar{\textrm O}}$) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively. From Fig. 7(a), the sensitivity of RI for three diameters are obviously different. The change of SRI has no influence on C regardless of different diameters. On the other hand, the increase of RI induces the red shift of ${\bar{\textrm O}}$. And the slope of ${\bar{\textrm O}}$ increases with the decrease of cladding diameter. By performing an exponential fitting to the experimental data, expressions are obtained for each sensor with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively

$$\Delta \lambda = 4.174{E^{ - 36}}{\textrm{e}^{\frac{{RI}}{{0.018}}}}\textrm{ + }0.061,{R^2} = 99.1\%$$
$$\Delta \lambda = 7.661{E^{ - 30}}{\textrm{e}^{\frac{{RI}}{{0.022}}}}\textrm{ + }0.018,{R^2} = 98.8\%$$
$$\Delta \lambda = 1.459{E^{ - 29}}{\textrm{e}^{\frac{{RI}}{{0.022}}}}\textrm{ + }0.172,{R^2} = 98.5\%$$
here Δλ represents the change in the absolute value of the wavelength.

 

Fig. 7. (a) The experimental results of wavelength shifts as functions of the SRI for central core (C) and outer cores ${\bar{\textrm O}}$) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively. (b) The simulation wavelength shifts calculated from computed effective RI of simulation models

Download Full Size | PPT Slide | PDF

It can be concluded that when the cladding diameter is decreased from 94.3 to 93.2 and 89.8 µm, the maximum RI sensitivity at around 1.435 RIU, as shown by grey dashed line in the grey window of Fig. 7(a), is calculated to be 7.65 nm/RIU, 17.86 nm/ RIU and 42.83 nm/ RIU, respectively. Significantly, the sensitivity of the diameter etching of 4.5 µm (from 94.3 to 89.8 µm) is improved four times.

Figure 7(b) shows the simulation results that the wavelength shifts as functions of the SRI for outer cores with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively. The simulated wavelength shifts are calculated under a specified wavelength according to the computed effective RI, consistent with the simulations in Fig. 2(b). The simulation results are found to be in good agreement with the experimental results shown in Fig. 7(a). Unavoidably, the RI sensitivity enhancement within the range of 1.33-1.39 RIU, inferred from the experimental results as shown in Fig. 7(a), is not obvious due to the fundamental constraint of effective index variation in this range, as shown in Fig. 7(b). The RI sensitivity within the range of 1.39-1.42 RIU is as well improved by cladding etching.

The experimental and simulated results confirm that the sensitivity can be optimized, inferred from previous analysis, by tuning the thickness of the MCF cladding for the sensor fabrication. However, it can be concluded from the comparison of data trend in Fig. 7(a) and (b) that the fitting equations are different between the experiments and simulations. This is mainly due to the process control of the chemical etching and the difficulty of employing precise parameters for the simulation.

As for the experimental results, the fitting equations (Eqs. 57) are not only concluded from the experimental data, but also can be used for sensor calibration in future application. The calibration function of each sensor will be slightly different due to the fluctuation of fabrication process and sensor configuration, as least for current stage, which can be hopefully optimized for more precise process control in future.

To evaluate the temperature dependence of the eFBG-MCFs, direct measurements of deionized water at different temperatures are conducted. A high precision thermometer is placed close to the grating to calibrate the temperature. Figure 8 shows the wavelength shifts as linear functions of temperature for outer core (${\bar{\textrm O}}$) and central core (C) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively. The temperature sensitivities are measured to be 9.61 pm/°C, 9.89 pm/°C (diameter=89.8 µm); 9.84 pm/°C, 10.01 pm/°C (diameter=93.2 µm) and 9.41 pm/°C, 9.76 pm/°C (diameter=94.3 µm) for${\bar{\textrm O}}$ and C, respectively. The thermal sensitivity of ${\bar{\textrm O}}$ is slightly lower than the sensitivity of C due to the thermo-optic coefficient of water is weaker than that of the cladding (fused silica), which is similar to the behavior in conventional counterparts [13].

 

Fig. 8. The wavelength shifts as functions of the SRI for central core (C) and outer cores${\bar{\textrm O}}$) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively.

Download Full Size | PPT Slide | PDF

To evaluate the accuracy and stability of the sensor, the 93.2 µm probe was employed to monitor six RI solutions at temperature of 30°C, 40°C and 50°C, and the experiment results are plotted in Fig. 9. The temperature fluctuation is ±0.3°C. Figure 9(a) shows the results with the compensation of the central core, the measured RI value has good consistency with the actual RI value, and the maximum error calculated to be 0.66% at 30°C at 1.342 RIU, which establishes a high accuracy in the full SRI range. The Fig. 9(b) gives the results without the compensation of the central core, in which the results show great error. The results demonstrate that temperature compensation is necessary and essential for eFBG-MCFs, and the proposed sensor realizes a high accuracy and advantage of in-line and local temperature compensation.

 

Fig. 9. Error of measured RI value corresponding to actual RI value (a) with compensation and (b) without compensation

Download Full Size | PPT Slide | PDF

Based on the obtained results, the proposed configuration involving eFBG-MCFs demonstrates the potential to perform in-situ simultaneous and accurate measurements of refractive index and temperature. Compared with the counterparts reported in the literatures, the proposed configuration has advantages of easy facility and high capability of in-line and in-situ temperature compensation, particularly, within micro environment. Additionally, the multiple outer cores contribute the precision and performance improvement for fabrication by averaging and balancing the read-out data from six outer cores. Furthermore, the eFBG-MCFs, undoubtedly, will inherit the major merit of FBGs with the great potential for distributed RI sensing.

5. Conclusion

A refractive index sensor with temperature in-line compensation based on eFBG-MCFs is proposed and experimentally demonstrated. Theoretical analysis and experimental results reveal that the FBGs in the distributed cores of the fabricated sensor can easily discriminate the RI and temperature due to the same longitudinal locations of the outer cores and the central core. The RI sensitivity of the FBGs in the outer cores increases as the cladding diameter decreases by the chemical etching, while the central core maintains RI-insensitivity. By taking advantage of this feature, the central core can perform as in-line and in-situ temperature compensator for RI sensing. The maximum sensitivity 42.83 nm/ RIU could be obtained at around 1.435 RIU, and the temperature sensitivity is 9.89 pm/°C. This device has great potential on RI sensing with the main feature of RI and temperature discrimination, and other merits of easy achievement, small size and high stability.

Funding

Major Technology Innovation of Hubei Province (2018AAA016); Fundamental Research Funds for the Central Universities (2019-zy-022); National Key Research and Development Program of China (2017YFB0405501).

Disclosures

The authors declare no conflicts of interest.

References

1. L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006). [CrossRef]  

2. L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007). [CrossRef]  

3. J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003). [CrossRef]  

4. A. Rajabzadeh, R. Heusdens, and R. C. Hendriks, “Calculation of the Mean Strain of Smooth Non-Uniform Strain Fields Using Conventional FBG Sensors,” J. Lightwave Technol. 36(17), 3716–3725 (2018). [CrossRef]  

5. X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014). [CrossRef]  

6. K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004). [CrossRef]  

7. S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014). [CrossRef]  

8. A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005). [CrossRef]  

9. N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006). [CrossRef]  

10. X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005). [CrossRef]  

11. J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017). [CrossRef]  

12. X. Shu, B. A. Gwandu, and Y. Liu, “Sampled fiber Bragg grating for simultaneous refractive-index and temperature measurement,” Opt. Lett. 26(11), 774 (2001). [CrossRef]  

13. J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007). [CrossRef]  

14. A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005). [CrossRef]  

15. D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012). [CrossRef]  

16. C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012). [CrossRef]  

17. C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010). [CrossRef]  

18. R. M. Silva, M. S. Ferreira, and J. Kobelke, “Simultaneous measurement of curvature and strain using a suspended multicore fiber,” Opt. Lett. 36(19), 3939 (2011). [CrossRef]  

19. P. Saffari, T. Allsop, and A. Adebayo, “Long period grating in multicore optical fiber: an ultra-sensitive vector bending sensor for low curvatures,” Opt. Lett. 39(12), 3508 (2014). [CrossRef]  

20. J. E. Antoniolopez, Z. S. Eznaveh, and P. Likamwa, “Multicore fiber sensor for high-temperature applications up to 1000°C,” Opt. Lett. 39(15), 4309 (2014). [CrossRef]  

21. P. S. Westbrook, T. Kremp, and K. S. Feder, “Continuous multicore optical fiber grating arrays for distributed sensing applications,” J. Lightwave Technol. 35(6), 1248–1252 (2017). [CrossRef]  

22. A. Zhou, Y. Zhang, and G. Li, “Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer,” Opt. Lett. 36(16), 3221 (2011). [CrossRef]  

23. D. A. May-Arrioja and J. R. Guzman-Sepulveda, “Highly sensitive fiber optic refractive index sensor using multicore coupled structures,” J. Lightwave Technol. 35(13), 2695–2701 (2017). [CrossRef]  

24. F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

25. A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997). [CrossRef]  

26. K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006). [CrossRef]  

27. Y. Yuan, L. Wang, and L. Ding, “Theory, experiment, and application of optical fiber etching,” Appl. Opt. 51(24), 5845–5849 (2012). [CrossRef]  

28. A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005). [CrossRef]  

29. H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014). [CrossRef]  

30. J. Li, H. Wang, L.-P. Sun, Y. Huang, L. Jin, and B.-O. Guan, “Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing,” Opt. Express 22(26), 31917–31923 (2014). [CrossRef]  

References

  • View by:
  • |
  • |
  • |

  1. L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
    [Crossref]
  2. L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
    [Crossref]
  3. J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003).
    [Crossref]
  4. A. Rajabzadeh, R. Heusdens, and R. C. Hendriks, “Calculation of the Mean Strain of Smooth Non-Uniform Strain Fields Using Conventional FBG Sensors,” J. Lightwave Technol. 36(17), 3716–3725 (2018).
    [Crossref]
  5. X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
    [Crossref]
  6. K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
    [Crossref]
  7. S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
    [Crossref]
  8. A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
    [Crossref]
  9. N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
    [Crossref]
  10. X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
    [Crossref]
  11. J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
    [Crossref]
  12. X. Shu, B. A. Gwandu, and Y. Liu, “Sampled fiber Bragg grating for simultaneous refractive-index and temperature measurement,” Opt. Lett. 26(11), 774 (2001).
    [Crossref]
  13. J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
    [Crossref]
  14. A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
    [Crossref]
  15. D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
    [Crossref]
  16. C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
    [Crossref]
  17. C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
    [Crossref]
  18. R. M. Silva, M. S. Ferreira, and J. Kobelke, “Simultaneous measurement of curvature and strain using a suspended multicore fiber,” Opt. Lett. 36(19), 3939 (2011).
    [Crossref]
  19. P. Saffari, T. Allsop, and A. Adebayo, “Long period grating in multicore optical fiber: an ultra-sensitive vector bending sensor for low curvatures,” Opt. Lett. 39(12), 3508 (2014).
    [Crossref]
  20. J. E. Antoniolopez, Z. S. Eznaveh, and P. Likamwa, “Multicore fiber sensor for high-temperature applications up to 1000°C,” Opt. Lett. 39(15), 4309 (2014).
    [Crossref]
  21. P. S. Westbrook, T. Kremp, and K. S. Feder, “Continuous multicore optical fiber grating arrays for distributed sensing applications,” J. Lightwave Technol. 35(6), 1248–1252 (2017).
    [Crossref]
  22. A. Zhou, Y. Zhang, and G. Li, “Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer,” Opt. Lett. 36(16), 3221 (2011).
    [Crossref]
  23. D. A. May-Arrioja and J. R. Guzman-Sepulveda, “Highly sensitive fiber optic refractive index sensor using multicore coupled structures,” J. Lightwave Technol. 35(13), 2695–2701 (2017).
    [Crossref]
  24. F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5
  25. A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997).
    [Crossref]
  26. K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
    [Crossref]
  27. Y. Yuan, L. Wang, and L. Ding, “Theory, experiment, and application of optical fiber etching,” Appl. Opt. 51(24), 5845–5849 (2012).
    [Crossref]
  28. A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
    [Crossref]
  29. H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
    [Crossref]
  30. J. Li, H. Wang, L.-P. Sun, Y. Huang, L. Jin, and B.-O. Guan, “Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing,” Opt. Express 22(26), 31917–31923 (2014).
    [Crossref]

2018 (1)

2017 (3)

2014 (6)

P. Saffari, T. Allsop, and A. Adebayo, “Long period grating in multicore optical fiber: an ultra-sensitive vector bending sensor for low curvatures,” Opt. Lett. 39(12), 3508 (2014).
[Crossref]

J. E. Antoniolopez, Z. S. Eznaveh, and P. Likamwa, “Multicore fiber sensor for high-temperature applications up to 1000°C,” Opt. Lett. 39(15), 4309 (2014).
[Crossref]

H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
[Crossref]

J. Li, H. Wang, L.-P. Sun, Y. Huang, L. Jin, and B.-O. Guan, “Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing,” Opt. Express 22(26), 31917–31923 (2014).
[Crossref]

X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
[Crossref]

S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
[Crossref]

2012 (3)

D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
[Crossref]

C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
[Crossref]

Y. Yuan, L. Wang, and L. Ding, “Theory, experiment, and application of optical fiber etching,” Appl. Opt. 51(24), 5845–5849 (2012).
[Crossref]

2011 (2)

2010 (1)

C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
[Crossref]

2007 (2)

J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
[Crossref]

L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
[Crossref]

2006 (3)

N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
[Crossref]

L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
[Crossref]

K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
[Crossref]

2005 (4)

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
[Crossref]

X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
[Crossref]

A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
[Crossref]

2004 (1)

K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
[Crossref]

2003 (1)

J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003).
[Crossref]

2001 (1)

1997 (1)

A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997).
[Crossref]

Adebayo, A.

Allsop, T.

Anand, A.

J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003).
[Crossref]

Antoniolopez, J. E.

Aristilde, S.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Baptista, J. M.

C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
[Crossref]

Campopiano, S.

A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
[Crossref]

A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
[Crossref]

Chen, N.

N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
[Crossref]

Chen, X.

K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
[Crossref]

X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
[Crossref]

K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
[Crossref]

Cheng, P.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Cheng, S.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Chesini, G.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Chryssis, A. N.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

Cordeiro, C. M. B.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Cruz, A. R. D.

D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
[Crossref]

Cui, Y.

N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
[Crossref]

Cusano, A.

A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
[Crossref]

Cutolo, A.

A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
[Crossref]

Dagenais, M.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

Dai, Y.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Davis, M. A.

A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997).
[Crossref]

Ding, L.

Du, C.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Enríquez, D. A. C.

D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
[Crossref]

Eznaveh, Z. S.

Feder, K. S.

Ferreira, M. S.

Franco, M. A. R.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Giraldi, M. T. M. R.

D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
[Crossref]

Gouveia, C.

C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
[Crossref]

Guan, B.-O.

Guang Q, X.

H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
[Crossref]

Guzman-Sepulveda, J. R.

Gwandu, B. A.

Hao, Z.

L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
[Crossref]

Hendriks, R. C.

Heusdens, R.

Hu, W.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Huang, Y.

Iadicicco, A.

A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
[Crossref]

A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
[Crossref]

Jayaraman, N.

S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
[Crossref]

Jin, L.

J. Li, H. Wang, L.-P. Sun, Y. Huang, L. Jin, and B.-O. Guan, “Etching Bragg gratings in Panda fibers for the temperature-independent refractive index sensing,” Opt. Express 22(26), 31917–31923 (2014).
[Crossref]

L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
[Crossref]

Jorge, P. A. S.

C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
[Crossref]

Kersey, A.

A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997).
[Crossref]

Kobelke, J.

Kremp, T.

Lee, S. B.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

Lee, S. M.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

Leng, J.

J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003).
[Crossref]

Li, C.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Li, G.

Li, J.

Liao, C. R.

C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
[Crossref]

Likamwa, P.

Liu, L.

L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
[Crossref]

Liu, X.

X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
[Crossref]

Liu, Y.

May-Arrioja, D. A.

Mumtaz, F.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Nogueira, R. N.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Oliveira, R.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Osório, J. H.

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Patrick, H. J.

A. Kersey, M. A. Davis, and H. J. Patrick, “Fiber grating sensors,” J. Lightwave Technol. 15(8), 1442–1463 (1997).
[Crossref]

Rajabzadeh, A.

Rajibul I, M.

H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
[Crossref]

Saffari, P.

Saini, S. S.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

Shao, L. Y.

J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
[Crossref]

Shu, X.

Silva, R. M.

Sridevi, S.

S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
[Crossref]

Sun, L.-P.

Vasu K, S.

S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
[Crossref]

Wang, D. N.

C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
[Crossref]

Wang, H.

Wang, L.

Wang, T.

X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
[Crossref]

Wang, Y.

C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
[Crossref]

Westbrook, P. S.

Wu, Y.

X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
[Crossref]

Yan, J.

J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
[Crossref]

Yang, M.

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Yuan, Y.

Yun, B.

N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
[Crossref]

Zhang, A. P.

J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
[Crossref]

Zhang, H.

L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
[Crossref]

Zhang, L.

K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
[Crossref]

X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
[Crossref]

K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
[Crossref]

Zhang, W.

L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
[Crossref]

Zhang, Y.

Zhao, Q.

L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
[Crossref]

Zhou, A.

Zhou, K.

K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
[Crossref]

X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
[Crossref]

K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
[Crossref]

Zhou Y, H.

H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
[Crossref]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

N. Chen, B. Yun, and Y. Cui, “Cladding mode resonances of etch-eroded fiber Bragg grating for ambient refractive index sensing,” Appl. Phys. Lett. 88(13), 133902 (2006).
[Crossref]

Electron. Lett. (1)

K. Zhou, X. Chen, and L. Zhang, “High-sensitivity optical chemsensor based on etched D-fibre Bragg gratings,” Electron. Lett. 40(4), 232–234 (2004).
[Crossref]

IEEE Photonics Technol. Lett. (6)

C. R. Liao, Y. Wang, and D. N. Wang, “Fiber In-Line Mach–Zehnder Interferometer Embedded in FBG for Simultaneous Refractive Index and Temperature Measurement,” IEEE Photonics Technol. Lett. 22(22), 1686–1688 (2010).
[Crossref]

X. Chen, K. Zhou, and L. Zhang, “Optical chemsensor based on etched tilted Bragg grating structures in multimode fiber,” IEEE Photonics Technol. Lett. 17(4), 864–866 (2005).
[Crossref]

L. Jin, W. Zhang, and H. Zhang, “An embedded FBG sensor for simultaneous measurement of stress and temperature,” IEEE Photonics Technol. Lett. 18(1), 154–156 (2006).
[Crossref]

X. Liu, T. Wang, and Y. Wu, “Dual-Parameter Sensor Based on Tapered FBG Combined with Microfiber Cavity,” IEEE Photonics Technol. Lett. 26(8), 817–820 (2014).
[Crossref]

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, “High sensitivity evanescent field fiber Bragg grating sensor,” IEEE Photonics Technol. Lett. 17(6), 1253–1255 (2005).
[Crossref]

A. Iadicicco, S. Campopiano, and A. Cutolo, “Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements,” IEEE Photonics Technol. Lett. 17(7), 1495–1497 (2005).
[Crossref]

IEEE Sens. J. (3)

C. Gouveia, P. A. S. Jorge, and J. M. Baptista, “Fabry–Pérot Cavity Based on a High-Birefringent Fiber Bragg Grating for Refractive Index and Temperature Measurement,” IEEE Sens. J. 12(1), 17–21 (2012).
[Crossref]

A. Iadicicco, A. Cusano, and S. Campopiano, “Thinned fiber Bragg gratings as refractive index sensors,” IEEE Sens. J. 5(6), 1288–1295 (2005).
[Crossref]

J. Yan, A. P. Zhang, and L. Y. Shao, “Simultaneous Measurement of Refractive Index and Temperature by Using Dual Long-Period Gratings with an Etching Process,” IEEE Sens. J. 7(9), 1360–1361 (2007).
[Crossref]

J. Lightwave Technol. (4)

Meas. Sci. Technol. (1)

K. Zhou, X. Chen, and L. Zhang, “Implementation of optical chemsensors based on HF-etched fiber Bragg grating structures,” Meas. Sci. Technol. 17(5), 1140–1145 (2006).
[Crossref]

Opt. Express (1)

Opt. Fiber Technol. (2)

L. Liu, Z. Hao, and Q. Zhao, “Temperature-independent FBG pressure sensor with high sensitivity,” Opt. Fiber Technol. 13(1), 78–80 (2007).
[Crossref]

J. H. Osório, R. Oliveira, S. Aristilde, G. Chesini, M. A. R. Franco, R. N. Nogueira, and C. M. B. Cordeiro, “Bragg gratings in surface-core fibers: Refractive index and directional curvature sensing,” Opt. Fiber Technol. 34, 86–90 (2017).
[Crossref]

Opt. Laser Technol. (1)

D. A. C. Enríquez, A. R. D. Cruz, and M. T. M. R. Giraldi, “Hybrid FBG–LPG sensor for surrounding refractive index and temperature simultaneous discrimination,” Opt. Laser Technol. 44(4), 981–986 (2012).
[Crossref]

Opt. Lett. (5)

Sens. Actuators, A (1)

J. Leng and A. Anand, “Structural health monitoring of smart composite materials by using EFPI and FBG sensors,” Sens. Actuators, A 103(3), 330–340 (2003).
[Crossref]

Sens. Actuators, B (2)

S. Sridevi, S. Vasu K, and N. Jayaraman, “Optical bio-sensing devices based on etched fiber Bragg gratings coated with carbon nanotubes and graphene oxide along with a specific dendrimer,” Sens. Actuators, B 195, 150–155 (2014).
[Crossref]

H. Zhou Y, X. Guang Q, and M. Rajibul I, “Simultaneous measurement of aliphatic alcohol concentration and temperature based on etched taper FBG,” Sens. Actuators, B 202, 959–963 (2014).
[Crossref]

Other (1)

F. Mumtaz, P. Cheng, C. Li, S. Cheng, C. Du, M. Yang, Y. Dai, and W. Hu, “A design of taper-like etched multicore fiber refractive index-insensitive a temperature highly sensitive Mach-Zehnder interferometer,” IEEE Sensors Journal. 2020 Mar 5

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (9)

Fig. 1.
Fig. 1. Simulated e-field distributions of the center-core mode with diameters of (a) 150 µm, (b) 117 µm, (c) 91 µm and (d) 88 µm, and the outer-core modes with diameters of (e) 150 µm, (f) 117 µm, (g) 91 µm and (h) 88 µm.
Fig. 2.
Fig. 2. (a) Effective RI of central core and one of the outer cores for different cladding diameters of MCFs (SRI=1.333). (b) Effective RI of central core and outer core for MCF diameters of 91 µm, 93 µm and 95 µm under different SRI
Fig. 3.
Fig. 3. The reflection spectra of FBGs in MCF
Fig. 4.
Fig. 4. The microscope images of cross-section for unetched MCF (a) and etched MCFs with diameters of (b) 93.2 µm, (c) 89.8 µm, and their side-views (d-f).
Fig. 5.
Fig. 5. Experimental setup of the proposed RI sensor and the schematic diagram of the probe.
Fig. 6.
Fig. 6. The evolution of the resonance wavelengths shifts of two types of cores, central core (C1) and outer cores (O1-O6)
Fig. 7.
Fig. 7. (a) The experimental results of wavelength shifts as functions of the SRI for central core (C) and outer cores ${\bar{\textrm O}}$) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively. (b) The simulation wavelength shifts calculated from computed effective RI of simulation models
Fig. 8.
Fig. 8. The wavelength shifts as functions of the SRI for central core (C) and outer cores${\bar{\textrm O}}$) with diameters of 89.8 µm, 93.2 µm and 94.3 µm, respectively.
Fig. 9.
Fig. 9. Error of measured RI value corresponding to actual RI value (a) with compensation and (b) without compensation

Equations (7)

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

λ C = 2 n e f f , C Λ
λ O = 2 n e f f , O Λ
Δ λ C λ c = ( 1 n e f f , c n e f f , C T + 1 Λ Λ α T ) Δ T = ( ζ C + α ) Δ T
Δ λ O λ O = ( 1 n e f f , O n e f f , O T + 1 Λ Λ α T ) Δ T + ( 1 n e f f , O n e f f O S R I ) Δ S R I = ( ζ O + α ) Δ T + κ S R I
Δ λ = 4.174 E 36 e R I 0.018  +  0.061 , R 2 = 99.1 %
Δ λ = 7.661 E 30 e R I 0.022  +  0.018 , R 2 = 98.8 %
Δ λ = 1.459 E 29 e R I 0.022  +  0.172 , R 2 = 98.5 %

Metrics