Abstract

We designed and fabricated a graded-index few-mode fiber (GI-FMF) with large effective mode area and low intermodal dispersion for Raman distributed temperature sensor (RDTS) to simultaneously achieve high spatial and temperature resolution over long distance. In experiment, we measured the spatial and temperature resolution of the RDTS using different types of fibers under different launch conditions based on a commercially available RDTS system. By using the GI-FMF under the overfilled launch condition, we achieved a 1 °C temperature resolution with a spatial resolution of 1.13 m at the distance of 25 km. The spatial resolution using the standard MMF degraded to 2.58 m with only a 0.3 °C higher temperature resolution in comparison. As a result, the GI-FMF under the few-mode operation condition can provide a desirable temperature resolution comparable with that of the MMF with a negligible degradation on spatial resolution. Moreover, the RDTS using the GI-FMF under the quasi-single mode operation condition achieved a temperature resolution of 4.7 °C at the distance of 25 km with a 2.2 °C improvement and no degradation on spatial resolution compared with that using the standard SMF.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

Raman distributed temperature sensors (RDTSs) based on optical time domain reflectometry (OTDR) and spontaneous Raman backscattering (spRBS) have been widely used in pipeline monitoring, oil well monitoring and fire alarm systems owing to their distinctive advantage of achieving temperature information along the entire sensing fiber with a high spatial and temperature resolution [1-5]. In RDTS, interrogation pulse is injected into the fiber and the spRBS light is detected for obtaining the temperature profile along the fiber [6]. However, due to the weak intensity of spRBS light, the RDTS usually has a poor signal-to-noise ratio (SNR), which limits both its temperature resolution and applicable distance.

Presently, there exists a compromise between the temperature and spatial resolution, which limits the RDTS for longer distance applications. In order to increase the peak power of the probe pulse which is limited by the stimulated Raman scattering effect, multimode fibers (MMFs) with large effective mode area (Aeff) and as a result, high threshold power of nonlinear effect are commonly used as the sensing media [7,8]. However, the applicable distance is limited due to the severe degradation of the spatial resolution resulted from the large intermodal dispersion of MMFs [9]. For example, with a 10 ns probe pulse which corresponds to a theoretical spatial resolution of 1 m, the spatial resolution of RDTS using the MMF degrades to 1.2 m and 4 m at the distances of 10 km and 35 km, respectively [10]. In order to realize a desirable spatial resolution over longer distance (up to a few tens of kilometers), single mode fibers (SMFs), which are free from the intermodal dispersion, are necessary at the cost of severe degradation of temperature resolution due to their low threshold power of nonlinear effect. In order to improve the temperature resolution without degrading the spatial resolution, optical pulse coding techniques have been proposed to increase the input optical power as well as the SNR [11-14]. On the other hand, a step-index (SI) few-mode fiber (FMF) was proposed as the sensing fiber and enhanced the temperature resolution from 10 °C to 6 °C without degrading the spatial resolution. However, the SNR enhancement is not remarkable under the quasi-single mode operation condition [15].

In this paper, we propose an optimized graded-index few-mode fiber (GI-FMF) based RDTS with both high spatial and temperature resolution over long distance. We successfully designed and fabricated a GI-FMF with large Aeff and low intermodal dispersion. In experiment, we measured the spatial and temperature resolution of the RDTS using different types of fibers under different launch conditions based on a commercially available RDTS system. By using the GI-FMF under the overfilled launch condition, we achieved a 1 °C temperature resolution with a spatial resolution of 1.13 m at the distance of 25 km. The spatial resolution using the standard MMF degraded to 2.58 m with only a 0.3 °C improvement on temperature resolution at 25 km under the same experimental configuration. As a result, an obvious improved SNR was obtained with negligible degradation on spatial resolution. Moreover, by using a single mode wavelength division multiplexer (WDM), the GI-FMF based RDTS can be easily switched to quasi-single mode launch condition. We experimentally showed that 4.7 °C temperature resolution with an improvement of 2.2 °C and no degradation on spatial resolution over a distance of 25 km were successfully achieved compared with that using the standard SMF. The proposed GI-FMF has good compatibility with RDTS using either the standard SMF or MMF and can be conveniently employed without other modification on present RDTS systems.

2. Principle of RDTS

In RDTS, a high power optical interrogation pulse generated by the laser source is injected into and scattered by the fiber under test (FUT). The spRBS light is split into Stokes (S) and anti-Stokes (AS) light by a WDM and then detected by two avalanche photo-detectors (APDs), respectively. The power of received S and AS light can be described as [6]:

PS(z)=RS(z)eαPzeαSzP0,
PAS(z)=RAS(z)eαPzeαSzP0,
where P0 is the peak power of interrogation pulse, RS(z) and RAS(z) are the reflectivities of S and AS light at position z, αP, αS and αAS are the attenuation coefficients of interrogation pulse, S and AS light, respectively. The attenuation coefficients are assumed to be constants along the fiber. The reflectivities of S and AS light have different dependency on the temperature, which can be expressed as:
RS(z)(1λS)411exp[hΔν/kT(z)],
RAS(z)(1λAS)41exp[hΔν/kT(z)]1,
where h is the Plank constant, k is the Boltzmann constant, T(z) is the temperature at position z, Δν is the Raman frequency shift, λS and λAS are the wavelengths of S and AS light, respectively. As a result, the temperature profile along the fiber can be described by the power ratio of AS and S light as:
R(z)=PAS(z)PS(z)=e(αASαS)z(λASλS)4exp[hΔνkT(z)].
In practical applications, the attenuation coefficients of S and AS light are always different, which requires a pre-calibration to minimize the influence of fiber attenuation. For pre-calibration, the temperature profile can be rewritten as:
R(z)=Rcal(z)e(αASαS)z,
where, Rcal(z) is the temperature profile after pre-calibration. The natural logarithm of R(z) can be described as:
ln[R(z)]=(αASαS)z+ln[Rcal(z)].
Here we assumed that the temperature of fiber is a constant. The fiber attenuation coefficient −(αASαS) can be obtained from Eq. (7) using the curve fitting method. After pre-calibration, the temperature profile Rcal(z) can be extracted from Eq (6). It should be noted that the power of spRBS light is usually 60–70 dB below the peak power of injected pulse which leads to a poor SNR. As a result, a long averaging time is usually required for the RDTS in order to achieve a desirable temperature resolution.

3. Fiber design and fabrication

We adopted a GI-FMF design to realize RDTS with high SNR performance and long applicable distance. In order to minimize the intermodal dispersion, we employed a graded-index profile, which can be described as:

n(r)=n012Δ(r/R)α,
where n0 is the refractive index of the core center, R is the radius of core, Δ is the relative refractive index difference between the core and the cladding structure, and α represents the shape of the reflective index profile of the core. Since a larger Aeff design enables higher injected power while resulting in a larger intermodal dispersion, there is a tradeoff between temperature resolution and spatial resolution. In order to achieve a lower modal dispersion while keeping a desirable Aeff, we investigated the dependences of both differential mode delay (DMD) and Aeff of the GI-FMF on R at the wavelength of 1550 nm using a finite element method and the results are shown in Fig. 1. In consideration of the compatibility with conventional RDTS using the standard MMF, the Δ and α are fixed to be 1.1% and 2.0, respectively. The blue and red lines represent the Aeff of the fundamental mode and the DMD of the highest order mode supported by the GI-FMF, respectively. It can be observed that the Aeff increases almost linearly along with R while the DMD of the highest order mode increases slowly when R is smaller than 14 µm. As a result, we chose a core radius of 12 µm for fabrication in order to obtain a small DMD while keeping a desirable SNR. Compared with the standard MMF, the DMD of the GI-FMF decreases to about 9% of its original value with a comparatively small SNR degeneration of about 3 dB.

 figure: Fig. 1

Fig. 1 The dependences of the DMD and Aeff of the GI-FMF on the core radius R.

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We also investigated the dependences of DMD and Aeff on α value. The calculated results are shown in Table 1. It can be observed that the optimal α value is around 2.0. The maximum absolute DMD of LP02 mode is around 176.1 ps/km. The Aeff of higher order modes such as LP21 and LP02 modes are more than 200 µm2, which indicates that the GI-FMF under the overfilled launch condition has a desirable nonlinear threshold and SNR.

Tables Icon

Table 1. Simulated parameters of the GI-FMF

The fiber was successfully fabricated without obvious degradation on other characteristics using a plasma chemical vapor deposition (PCVD) method. It should be mentioned that owing to its smaller core diameter, the manufacturing cost of GI-MMF may considerably lower than that of the standard MMF in mass production due to its higher fabrication yield and efficiency. The refractive index profile was measured using an S14 optical fiber index profiler and the result is shown in Fig. 2. The attenuation of the GI-FMF measured by a cutback method at the wavelength of 1550 nm is 0.24 dB/km. The GI-FMF can be conveniently spliced to either multimode or single mode WDM to realize the overfilled or quasi-single mode launch condition with a low splicing loss. The average splicing loss from the multimode WDM with a core diameter of 62.5 µm to the GI-FMF and from the GI-FMF to the SMF is 1 dB and 0.2 dB, respectively.

 figure: Fig. 2

Fig. 2 The measured refractive index profile of the GI-FMF.

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4. Experimental setup and results

The experimental setup is shown in Fig. 3. A high-power laser was used as the laser source with an output power of 17 dBm. The output light was modulated into pulses by an intensity modulator (IM) which was driven by an arbitrary waveform generator (AWG). The pulse width was 10 ns and the pulse repetition rate was 3 kHz. The pulses were amplified by an erbium-doped fiber amplifier (EDFA) to a level that a little below the nonlinearity threshold of the FUT. An optical bandpass filter (OBPF) was used to cutoff the amplified spontaneous emission (ASE) of EDFA. After passing through the OBPF, the interrogation pulses were injected into FUT through a Raman-customized WDM. We used a multimode WDM with a core diameter of 62.5 µm and a single mode WDM to realize the overfilled and quasi-single mode launch condition, respectively. The spRBS light of FUT was divided into S and AS light by the WDM and then detected by two APDs. The output signals of APD were sampled by a 2-channel analog-to-digital converter (ADC) with a 12-bit accuracy and a 250-MHz sampling rate. The sampled traces were averaged by 105 times to improve the SNR within a measurement time of about 90 seconds.

 figure: Fig. 3

Fig. 3 The experimental setup. IM: intensity modulator; EDFA: erbium-doped fiber amplifier; OBPF: optical bandpass filter; WDM: wavelength division multiplexer; FUT: fiber under test; AWG: arbitrary waveform generator; APD: avalanche photo-detector; ADC: analog-to-digital converter.

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4.1. Few-mode operation condition

First, we employed an overfilled launch condition to increase the optical power injected into the GI-FMF. We adjusted the optical power injected into different sensing fibers to a level that is just below the threshold of the stimulated Raman scattering effect, and then measured the average power injected into different fibers. The nonlinear threshold power was calculated by dividing the average power by the pulse duty ratio. Since the higher order modes were excited, the nonlinear threshold was enlarged to 4.7 W under the overfilled launch condition. For comparison purposes, the S and AS light intensity traces of the standard MMF (OM2), SMF (G652) and GI-FMF under the overfilled launch condition were measured with interrogation pulses whose peak power were just below their nonlinear thresholds. The measured results are shown in Fig. 4. It can be observed that by using the GI-FMF under the overfilled launch condition, the dynamic ranges of S and AS light traces are close to that of the MMF and have an improvement of 10.8 dB and 10.6 dB, respectively, compared with that of the SMF. Besides, we measured the S and AS light attenuation factors of the GI-FMF, which are 0.247 dB/km and 0.289 dB/km under the overfilled launch condition, while those of MMF are 0.252 dB/km and 0.3 dB/km, respectively. Due to the smaller attenuation of the GI-FMF, the difference between the SNR performance of RDTS using the GI-FMF and MMF will minimize at longer distances.

 figure: Fig. 4

Fig. 4 Output light intensity as a function of distance of (a) S and (b) AS light using different fibers.

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The temperature profile along the GI-FMF fiber under the overfilled launch condition was measured and the results are shown in Fig. 5(a)5(c). Three sensing sections were set at the distance of 10 km, 19 km, and 23 km, respectively. The temperature of the sensing sections were controlled by using a water bath and the length of each sensing section was about 20 m. The room temperature was around 25 °C. The temperature resolution profiles of the GI-FMF and the MMF were obtained by calculating the root mean square error of the temperature profile with a window of 1 km and the results are shown in Fig. 5(d). It can be observed that the GI-FMF under the overfilled launch condition can provide a high temperature resolution close to that using the MMF. At the distance of 25 km, a temperature resolution of 1 °C was achieved by using the GI-FMF.

 figure: Fig. 5

Fig. 5 The temperature profiles of the GI-FMF under the overfilled launch condition at (a) 10 km, (b) 19 km, and (c) 23 km, and (d) the temperature resolution profile using the GI-FMF and MMF.

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In order to investigate the spatial resolution degradation of the GI-MMF under the overfilled launch condition, we measured the shape of 10 ns interrogation pulse of the MMF, SMF and GI-MMF after passing through a distance of 25 km. The results are shown in Fig. 6. It can be observed that the full-width-of-half-maximum of the interrogation pulse for the GI-FMF is kept to be 10.3 ns under the overfilled launch condition. It should be noted that the intermodal dispersion still results in an overshooting at the beginning of the pulse and a tail at the end of the pulse in comparison with the SMF. On the other hand, the interrogation pulse passing through the MMF shows a broadening of 8.6 ns and results in a severe degradation on spatial resolution.

 figure: Fig. 6

Fig. 6 The shape of interrogation pulse at the far-end of 25-km long SMF, MMF and GI-FMF under the overfilled launch condition.

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The spatial resolution at the distances of 10 km, 19 km, and 23 km were measured and the results are shown in Fig. 7(a)7(c). It can be observed that the spatial resolution of RDTS is 1.04 m at 19 km and 1.13 m at 23 km, respectively. The far-end spatial resolution of RDTS using the MMF were measured and the result is shown in Fig. 7(d) for comparison. In this case, the spatial resolution degrades to 2.58 m at the distance of 22 km due to the larger intermodal dispersion. It should be noted that for longer distance RDTS applications, although the degradation on spatial resolution of RDTS using GI-FMF under the overfilled launch condition is inevitable, it is expected to exhibit a distinctive improvement compared with that using the standard MMF due to its smaller DMD.

 figure: Fig. 7

Fig. 7 The spatial resolution of the RDTS based on the GI-FMF under the overfilled launch condition at (a) 10 km, (b) 19 km and (c) 23 km, and the spatial resolution of the RDTS based on (d) MMF at around 22 km.

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4.2. Quasi-single mode operation condition

We also investigated the RDTS using the GI-FMF under the quasi-single mode launch condition by center launching the light to the fiber through a single-mode WDM to achieve a higher spatial resolution over a long distance. The nonlinear thresholds of both the GI-FMF under the quasi-single mode launch condition and the SMF were measured to be 1.26 W and 1.22 W respectively with the same method described before. The interrogation pulse was launched into the GI-FMF and SMF with a peak power just below the nonlinear threshold. The intensity of S and AS light were measured and the results are shown in Fig. 8. It can be observed that by employing the quasi-single mode launch condition, dynamic ranges of 27.2 dB and 26.9 dB of S and AS light are achieved with an improvement of 2.5 dB and 2.7 dB, respectively, compared with that using the standard SMF. The results indicate that the GI-FMF may provide an improved SNR for RDTS compared with the SMF.

 figure: Fig. 8

Fig. 8 The output traces of APDs of (a) S light and (b) AS light with different fibers.

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The experimental setup is same as that shown in Fig. 3. The temperature profile along the fiber was measured and the results are shown in Fig. 9(a)9(c). The temperature resolution profiles of the GI-FMF and SMF were shown in Fig. 9(d). At the distance of 25 km, a temperature resolution of 4.7 °C was achieved by using the GI-FMF with an improvement of 2.2 °C compared with that using the SMF. Moreover, there is no degradation on spatial resolution using both the GI-FMF and SMF under the quasi-single mode launch condition, as shown in Fig. 10(a)10(b).

 figure: Fig. 9

Fig. 9 The temperature profiles of the GI-FMF under the quasi-single mode launch condition at (a) 10 km, (b) 19 km, and (c) 23 km, and (d) the temperature resolution profiles of the GI-FMF and SMF.

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 figure: Fig. 10

Fig. 10 The spatial resolution of the RDTS based on the GI-FMF under quasi-single mode launch condition at (a) 23 km, and the spatial resolution of the RDTS based on (b) SMF at around 21 km.

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The spatial and temperature resolution of the RDTS using different types of fibers and operation conditions with a 10 ns probe pulse are shown in Table 2. The results indicate that the GI-FMF under the overfilled launch condition can provide a desirable temperature resolution comparable with that of the MMF with a negligible spatial resolution degradation.

Tables Icon

Table 2. The spatial and temperature resolution of the RDTS using different fibers and operation conditions

5. Conclusion

We designed and fabricated an optimized GI-FMF with large Aeff and low intermodal dispersion for RDTS with high spatial resolution as well as a desirable temperature resolution over a long measuring distance. By carefully choosing the parameters, the DMD of the GI-FMF can be suppressed while keeping a large Aeff. In experiment, we measured the spatial and temperature resolution of the RDTS using different types of fibers and under different operation conditions based on a commercially available RDTS. By using the GI-FMF under the overfilled launch condition, we achieved a 1 °C temperature resolution with a spatial resolution of 1.13 m at the distance of 25 km. For comparison, the spatial resolution using the standard MMF degraded to 2.58 m with only a 0.3 °C improvement on temperature resolution. As a result, the GI-FMF under the overfilled launch condition can provide a desirable temperature resolution comparable with that of the MMF with a negligible degradation on spatial resolution. Moreover, the RDTS using the GI-FMF under quasi-single mode launch condition can achieve a temperature resolution of 4.7 °C at the distance of 25 km with a 2.2 °C improvement and no spatial resolution degradation compared with that of the standard SMF.

Funding

National Natural Science Foundation of China under Grant 61775138, 61620106015; Open Projects Foundation of Yangtze Optical Fiber and Cable Joint Stock Limited Company (YOFC) under Grant SKLD1601.

References

1. “Technology Focus: Optical-fiber sensors,” Nat. Photonics2(3), 143–158 (2008).

2. A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985). [CrossRef]  

3. K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999). [CrossRef]  

4. Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003). [CrossRef]  

5. I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015). [CrossRef]  

6. X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012). [CrossRef]   [PubMed]  

7. J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985). [CrossRef]  

8. M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007). [CrossRef]  

9. M. A. Farahani and T. Gogolla, “Spontaneous Raman scattering in optical fibers with modulated probe light for distributed temperature Raman remote sensing,” J. Lightwave Technol. 17(8), 1379–1391 (1999). [CrossRef]  

10. A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

11. J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006). [CrossRef]  

12. G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

13. G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007). [CrossRef]  

14. M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011). [CrossRef]  

15. M. Wang, H. Wu, M. Tang, Z. Zhao, Y. Dang, C. Zhao, R. Liao, W. Chen, S. Fu, C. Yang, W. Tong, P. P. Shum, and D. Liu, “Few-mode fiber based Raman distributed temperature sensing,” Opt. Express 25(5), 4907–4916 (2017). [CrossRef]   [PubMed]  

References

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  1. “Technology Focus: Optical-fiber sensors,” Nat. Photonics2(3), 143–158 (2008).
  2. A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
    [Crossref]
  3. K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999).
    [Crossref]
  4. Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003).
    [Crossref]
  5. I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
    [Crossref]
  6. X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012).
    [Crossref] [PubMed]
  7. J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
    [Crossref]
  8. M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
    [Crossref]
  9. M. A. Farahani and T. Gogolla, “Spontaneous Raman scattering in optical fibers with modulated probe light for distributed temperature Raman remote sensing,” J. Lightwave Technol. 17(8), 1379–1391 (1999).
    [Crossref]
  10. A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.
  11. J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
    [Crossref]
  12. G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.
  13. G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
    [Crossref]
  14. M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
    [Crossref]
  15. M. Wang, H. Wu, M. Tang, Z. Zhao, Y. Dang, C. Zhao, R. Liao, W. Chen, S. Fu, C. Yang, W. Tong, P. P. Shum, and D. Liu, “Few-mode fiber based Raman distributed temperature sensing,” Opt. Express 25(5), 4907–4916 (2017).
    [Crossref] [PubMed]

2017 (1)

2015 (1)

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

2012 (1)

X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012).
[Crossref] [PubMed]

2011 (1)

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

2007 (2)

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

2006 (1)

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

2003 (1)

Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003).
[Crossref]

1999 (2)

1985 (2)

A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
[Crossref]

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

Bao, X.

X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012).
[Crossref] [PubMed]

Baronti, F.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Barsacchi, R.

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Bibby, G. W.

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

Bolognini, G.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Brugger, M.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

Chen, L.

X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012).
[Crossref] [PubMed]

Chen, W.

Dakin, J. P.

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

Dang, Y.

Di Pasquale, F.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Duckey, L.

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

Farahani, M. A.

Faralli, S.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Fu, S.

Gogolla, T.

Gold, M. P.

A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
[Crossref]

Guillermain, E.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

Hartog, A. H.

A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
[Crossref]

Huai Hoo, K.

K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999).
[Crossref]

Kim, A. K.

Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003).
[Crossref]

Kim, P.

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Kuhnhenn, J.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

Lazzeri, A.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Leach, A. P.

A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
[Crossref]

Lee, D.

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Lees, G. P.

K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999).
[Crossref]

Liao, R.

Liu, D.

Liu, Z.

Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003).
[Crossref]

Nannipieri, T.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

Nebendahl, B.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

Newson, T. P.

K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999).
[Crossref]

Park, J.

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Park, N.

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Pasquale, F. D.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

Pilhan, K.

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

Pilki, C.

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

Pratt, D. J.

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

Roncella, R.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Ross, J. N.

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

Rueck, C.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

Sacchi, G.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Sahu, P.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

Shum, P. P.

Signorini, A.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Soto, M.

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

Soto, M. A.

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

Soto, M.A.

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

Tang, M.

Toccafondo, I.

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

Tong, W.

Wang, M.

Wu, H.

Yang, C.

Zhao, C.

Zhao, Z.

Electron. Lett. (3)

A. H. Hartog, A. P. Leach, and M. P. Gold, “Distributed temperature sensing in solid-core fibres,” Electron. Lett. 21(23), 1061–1062 (1985).
[Crossref]

K. Huai Hoo, G. P. Lees, and T. P. Newson, “1.65 µ m Raman-based distributed temperature sensor,” Electron. Lett. 35(21), 1869–1871 (1999).
[Crossref]

J. P. Dakin, D. J. Pratt, G. W. Bibby, and J. N. Ross, “Distributed optical fibre Raman temperature sensor using a semiconductor light source and detector,” Electron. Lett. 21(13), 569–570 (1985).
[Crossref]

IEEE Photon. Technol. Lett. (2)

I. Toccafondo, T. Nannipieri, A. Signorini, E. Guillermain, J. Kuhnhenn, M. Brugger, and F. D. Pasquale, “Raman Distributed Temperature Sensing at CERN,” IEEE Photon. Technol. Lett. 27(20), 2182–2185 (2015).
[Crossref]

J. Park, G. Bolognini, L. Duckey, K. Pilhan, C. Pilki, F. D. Pasquale, and N. Park, “Raman-based distributed temperature sensor with simplex coding and link optimization,” IEEE Photon. Technol. Lett. 18(17), 1879–1881 (2006).
[Crossref]

J. Fire Prot. Eng. (1)

Z. Liu and A. K. Kim, “Review of Recent Developments in Fire Detection Technologies,” J. Fire Prot. Eng. 13(2), 129–151 (2003).
[Crossref]

J. Lightwave Technol. (1)

Meas. Sci. Technol. (1)

G. Bolognini, J. Park, M.A. Soto, N. Park, and F. Di Pasquale, “Analysis of distributed temperature sensing based on Raman scattering using OTDR coding and discrete Raman amplification,” Meas. Sci. Technol. 18(10), 3211 (2007).
[Crossref]

Opt. Express (1)

Opt. Lett. (1)

M. A. Soto, T. Nannipieri, A. Signorini, A. Lazzeri, F. Baronti, R. Roncella, G. Bolognini, and F. Di Pasquale, “Raman-based distributed temperature sensor with 1m spatial resolution over 26km SMF using low-repetition-rate cyclic pulse coding,” Opt. Lett. 36132557–2559 (2011).
[Crossref]

Proc. SPIE (1)

M. Soto, P. Sahu, S. Faralli, G. Sacchi, G. Bolognini, F. Di Pasquale, B. Nebendahl, and C. Rueck, “High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers,” Proc. SPIE 6619, 66193B (2007).
[Crossref]

Sensors (1)

X. Bao and L. Chen, “Recent Progress in Distributed Fiber Optic Sensors,” Sensors 12(7), 8601–8639 (2012).
[Crossref] [PubMed]

Other (3)

A. Signorini, S. Faralli, M. A. Soto, G. Sacchi, F. Baronti, R. Barsacchi, A. Lazzeri, R. Roncella, G. Bolognini, and F. Di Pasquale, “40 km Long-Range Raman-Based Distributed Temperature Sensor with Meter-Scale Spatial Resolution,” in Optical Fiber Communication Conference, OSA Technical Digest Series (Optical Society of America, 2010), paper OWL2.

G. Bolognini, J. Park, P. Kim, D. Lee, F. D. Pasquale, and N. Park, “Performance enhancement of Raman-based distributed temperature sensors using simplex codes,” in Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference (2006), paper OTuLl.

“Technology Focus: Optical-fiber sensors,” Nat. Photonics2(3), 143–158 (2008).

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Figures (10)

Fig. 1
Fig. 1 The dependences of the DMD and Aeff of the GI-FMF on the core radius R.
Fig. 2
Fig. 2 The measured refractive index profile of the GI-FMF.
Fig. 3
Fig. 3 The experimental setup. IM: intensity modulator; EDFA: erbium-doped fiber amplifier; OBPF: optical bandpass filter; WDM: wavelength division multiplexer; FUT: fiber under test; AWG: arbitrary waveform generator; APD: avalanche photo-detector; ADC: analog-to-digital converter.
Fig. 4
Fig. 4 Output light intensity as a function of distance of (a) S and (b) AS light using different fibers.
Fig. 5
Fig. 5 The temperature profiles of the GI-FMF under the overfilled launch condition at (a) 10 km, (b) 19 km, and (c) 23 km, and (d) the temperature resolution profile using the GI-FMF and MMF.
Fig. 6
Fig. 6 The shape of interrogation pulse at the far-end of 25-km long SMF, MMF and GI-FMF under the overfilled launch condition.
Fig. 7
Fig. 7 The spatial resolution of the RDTS based on the GI-FMF under the overfilled launch condition at (a) 10 km, (b) 19 km and (c) 23 km, and the spatial resolution of the RDTS based on (d) MMF at around 22 km.
Fig. 8
Fig. 8 The output traces of APDs of (a) S light and (b) AS light with different fibers.
Fig. 9
Fig. 9 The temperature profiles of the GI-FMF under the quasi-single mode launch condition at (a) 10 km, (b) 19 km, and (c) 23 km, and (d) the temperature resolution profiles of the GI-FMF and SMF.
Fig. 10
Fig. 10 The spatial resolution of the RDTS based on the GI-FMF under quasi-single mode launch condition at (a) 23 km, and the spatial resolution of the RDTS based on (b) SMF at around 21 km.

Tables (2)

Tables Icon

Table 1 Simulated parameters of the GI-FMF

Tables Icon

Table 2 The spatial and temperature resolution of the RDTS using different fibers and operation conditions

Equations (8)

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

P S ( z ) = R S ( z ) e α P z e α S z P 0 ,
P A S ( z ) = R A S ( z ) e α P z e α S z P 0 ,
R S ( z ) ( 1 λ S ) 4 1 1 exp [ h Δ ν / k T ( z ) ] ,
R A S ( z ) ( 1 λ A S ) 4 1 exp [ h Δ ν / k T ( z ) ] 1 ,
R ( z ) = P A S ( z ) P S ( z ) = e ( α A S α S ) z ( λ A S λ S ) 4 exp [ h Δ ν k T ( z ) ] .
R ( z ) = R c a l ( z ) e ( α A S α S ) z ,
ln [ R ( z ) ] = ( α A S α S ) z + ln [ R c a l ( z ) ] .
n ( r ) = n 0 1 2 Δ ( r / R ) α ,

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