Distributed optical fiber vibration sensors (DOFSs) such as those based on phase-sensitive optical time-domain reflectometry (φ-OTDR) have contributed to improve structural health monitoring (SHM). φ-OTDR allows distributed vibration sensing by analysing the interference properties of the backscattered/reflected signal when an optical pulse is launched into the sensing fiber. As the Rayleigh backscattered light is relatively weak, fiber Bragg grating (FBG) arrays can be inscribed in the sensing fiber to increase the signal-to-noise ratio. However, the interference of the signals reflected by two consecutive FBGs (containing information about the locally applied vibration) is subject to a polarization fading effect as the sensing fiber presents some birefringence. Therefore the states of polarization (SOP) of the interfering reflected signals are no longer fully aligned. The present work proposes a measurement setup to quantify the polarization effects in a direct detection phase-OTDR scheme through the polarization fading sensitivity (PFS) parameter.
{"title":"Measurement of polarization fading sensitivity in FBGs-assisted Phase-OTDR","authors":"Beni Fourier Sandah, M. Dossou, M. Wuilpart","doi":"10.1117/12.2677355","DOIUrl":"https://doi.org/10.1117/12.2677355","url":null,"abstract":"Distributed optical fiber vibration sensors (DOFSs) such as those based on phase-sensitive optical time-domain reflectometry (φ-OTDR) have contributed to improve structural health monitoring (SHM). φ-OTDR allows distributed vibration sensing by analysing the interference properties of the backscattered/reflected signal when an optical pulse is launched into the sensing fiber. As the Rayleigh backscattered light is relatively weak, fiber Bragg grating (FBG) arrays can be inscribed in the sensing fiber to increase the signal-to-noise ratio. However, the interference of the signals reflected by two consecutive FBGs (containing information about the locally applied vibration) is subject to a polarization fading effect as the sensing fiber presents some birefringence. Therefore the states of polarization (SOP) of the interfering reflected signals are no longer fully aligned. The present work proposes a measurement setup to quantify the polarization effects in a direct detection phase-OTDR scheme through the polarization fading sensitivity (PFS) parameter.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116025728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Przemyslaw Falak, Timothy Lee, Q. Sun, T. Vettenburg, D. Phillips, G. Brambilla, M. Beresna
We demonstrate a polarization analyser based on processing of speckle patterns generated by a scattering medium. Each speckle pattern at a given wavelength and polarization state is unique and deterministic, and thus the polarization angle alters the speckle pattern motif. The polarization state of a given input light is obtained using reconstructive linear algebra methods. The system consists of a femtosecond laser written scattering chip and a CMOS sensor and contains no moving parts, making the proposed solution is low-cost and compact. The linear polarization angle was accurately reconstructed over a 0-20° test range, with 6 arcminutes (1/10° ) standard error. To demonstrate an application as a polarimeter, we used the system to measure Faraday rotation in a SF59 lead silicate glass within an electromagnet. The magnetic field was successfully traced by determining the induced changes in the input beam’s linear polarization angle in the range 0-80 mT with 10 mT standard error.
{"title":"Magnetic field sensing using laser written birefringent scattering medium","authors":"Przemyslaw Falak, Timothy Lee, Q. Sun, T. Vettenburg, D. Phillips, G. Brambilla, M. Beresna","doi":"10.1117/12.2678130","DOIUrl":"https://doi.org/10.1117/12.2678130","url":null,"abstract":"We demonstrate a polarization analyser based on processing of speckle patterns generated by a scattering medium. Each speckle pattern at a given wavelength and polarization state is unique and deterministic, and thus the polarization angle alters the speckle pattern motif. The polarization state of a given input light is obtained using reconstructive linear algebra methods. The system consists of a femtosecond laser written scattering chip and a CMOS sensor and contains no moving parts, making the proposed solution is low-cost and compact. The linear polarization angle was accurately reconstructed over a 0-20° test range, with 6 arcminutes (1/10° ) standard error. To demonstrate an application as a polarimeter, we used the system to measure Faraday rotation in a SF59 lead silicate glass within an electromagnet. The magnetic field was successfully traced by determining the induced changes in the input beam’s linear polarization angle in the range 0-80 mT with 10 mT standard error.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"537 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116377746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Srivastava, F. Esposito, S. Campopiano, A. Iadicicco
This work proposes an in-fiber Mach-Zehnder interferometer (MZI) device which is fabricated by embedding a short section of double cladding fiber (DCF) in between two standard fibers utilising the core-offset splicing approach. Moreover, the DCF has a W-shaped refractive index (RI) profile, where the outer cladding has RI higher than inner one and core. Consequently, by modifying the thickness of the outer cladding, the mode transition of cladding modes from outer to inner cladding can be induced, with the possibility to tune the sensitivity to surrounding refractive index. Specifically, the outer cladding diameter was decreased by means of chemical etching down to a diameter of 112 µm and a sensitivity of -200 nm/RIU was achieved in the range 1.33-1.39, with a 2.5 gain in comparison to unetched fiber. The proposed sensing device has considerable compactness, low manufacturing cost and simplicity, as well as high sensitivity for future applications in chemical and biosensing domain and other related fields.
{"title":"Study of all-fiber Mach-Zehnder configuration with mode transition phenomena in double cladding fiber","authors":"A. Srivastava, F. Esposito, S. Campopiano, A. Iadicicco","doi":"10.1117/12.2678165","DOIUrl":"https://doi.org/10.1117/12.2678165","url":null,"abstract":"This work proposes an in-fiber Mach-Zehnder interferometer (MZI) device which is fabricated by embedding a short section of double cladding fiber (DCF) in between two standard fibers utilising the core-offset splicing approach. Moreover, the DCF has a W-shaped refractive index (RI) profile, where the outer cladding has RI higher than inner one and core. Consequently, by modifying the thickness of the outer cladding, the mode transition of cladding modes from outer to inner cladding can be induced, with the possibility to tune the sensitivity to surrounding refractive index. Specifically, the outer cladding diameter was decreased by means of chemical etching down to a diameter of 112 µm and a sensitivity of -200 nm/RIU was achieved in the range 1.33-1.39, with a 2.5 gain in comparison to unetched fiber. The proposed sensing device has considerable compactness, low manufacturing cost and simplicity, as well as high sensitivity for future applications in chemical and biosensing domain and other related fields.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115466960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Chapalo, A. Gusarov, K. Chah, A. Ioannou, A. Pospori, Y. Nan, K. Kalli, P. Mégret
Polymer fiber Bragg grating (FBGs) demonstrate a wider strain range and stronger temperature sensitivity compared to standard silica FBGs. Besides, their advantageous feature is sensitivity to humidity that enables FBG-based relative humidity (RH) sensing. However, practical realization of RH sensors requires temperature cross-sensitivity elimination. A certain optimal fiber pre-strain and gamma irradiation of perfluorinated (CYTOP) FBGs up to certain optimal dose are potential recently proposed solutions for this problem. In this work, we investigate temperature and RH response of FBGs inscribed line-by-line in a few-mode polymer fiber with 20-μm CYTOP core and 250-μm XYLEX overclad. We compare the cases of the pristine FBG sample and the sample received 200 kGy irradiation dose. The 200-kGy dose was previously confirmed to provide temperature sensitivity minimization at 40%RH. Here, we show the close-to-zero temperature sensitivity (≈1pm/°C) for 200-kGy dose at high RH value of 89%. Besides, we briefly analyze the stabilization process of FBGs response to strong and quick RH changes.
{"title":"Temperature and RH response of polymer CYTOP FBG treated by gamma radiation","authors":"I. Chapalo, A. Gusarov, K. Chah, A. Ioannou, A. Pospori, Y. Nan, K. Kalli, P. Mégret","doi":"10.1117/12.2678326","DOIUrl":"https://doi.org/10.1117/12.2678326","url":null,"abstract":"Polymer fiber Bragg grating (FBGs) demonstrate a wider strain range and stronger temperature sensitivity compared to standard silica FBGs. Besides, their advantageous feature is sensitivity to humidity that enables FBG-based relative humidity (RH) sensing. However, practical realization of RH sensors requires temperature cross-sensitivity elimination. A certain optimal fiber pre-strain and gamma irradiation of perfluorinated (CYTOP) FBGs up to certain optimal dose are potential recently proposed solutions for this problem. In this work, we investigate temperature and RH response of FBGs inscribed line-by-line in a few-mode polymer fiber with 20-μm CYTOP core and 250-μm XYLEX overclad. We compare the cases of the pristine FBG sample and the sample received 200 kGy irradiation dose. The 200-kGy dose was previously confirmed to provide temperature sensitivity minimization at 40%RH. Here, we show the close-to-zero temperature sensitivity (≈1pm/°C) for 200-kGy dose at high RH value of 89%. Besides, we briefly analyze the stabilization process of FBGs response to strong and quick RH changes.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115631409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Camilo Escobar-Vera, M. Soriano-Amat, H. Martins, D. Barrera, S. Martín-López, M. González-Herráez, M. R. Fernandez Ruiz
Optical fiber sensors are becoming a prominent solution to perform shape sensing thanks to their interesting and well-known advantages such as flexibility, lightweight, sensitivity, etc. However, the different approaches commonly used to date, which include fiber Bragg gratings, OFDR or OTDR architectures, are not able to achieve a fully distributed and fast performance over relatively long ranges (e.g., tens of meters) and with fine (cm-scale) resolution. Here, we present a novel scheme to perform curvature sensing attaining all the previously mentioned features by application of time-expanded phase-sensitive (TE-Φ)OTDR technology. TE-ΦOTDR is a promising distributed sensing technique that delivers a performance ranging between that of OFDR and ΦOTDR. As a proof-of-concept, we interrogate three cores of a multicore fiber (MCF) using TE-ΦOTDR, attaining curvature sensing with 10 cm resolution over a maximum measurable range of 125 m and a sampling rate of 50 Hz. The implementation of shape sensing schemes with the performance provided by TE-ΦOTDR technology may open the door to new and interesting applications in civil engineering, medicine and seismology.
{"title":"Towards shape-sensing using time-expanded ΦOTDR","authors":"Camilo Escobar-Vera, M. Soriano-Amat, H. Martins, D. Barrera, S. Martín-López, M. González-Herráez, M. R. Fernandez Ruiz","doi":"10.1117/12.2678431","DOIUrl":"https://doi.org/10.1117/12.2678431","url":null,"abstract":"Optical fiber sensors are becoming a prominent solution to perform shape sensing thanks to their interesting and well-known advantages such as flexibility, lightweight, sensitivity, etc. However, the different approaches commonly used to date, which include fiber Bragg gratings, OFDR or OTDR architectures, are not able to achieve a fully distributed and fast performance over relatively long ranges (e.g., tens of meters) and with fine (cm-scale) resolution. Here, we present a novel scheme to perform curvature sensing attaining all the previously mentioned features by application of time-expanded phase-sensitive (TE-Φ)OTDR technology. TE-ΦOTDR is a promising distributed sensing technique that delivers a performance ranging between that of OFDR and ΦOTDR. As a proof-of-concept, we interrogate three cores of a multicore fiber (MCF) using TE-ΦOTDR, attaining curvature sensing with 10 cm resolution over a maximum measurable range of 125 m and a sampling rate of 50 Hz. The implementation of shape sensing schemes with the performance provided by TE-ΦOTDR technology may open the door to new and interesting applications in civil engineering, medicine and seismology.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115746519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Romanet, Alexandre Matic, M. Zerbib, K. Phan Huy, Jordan Labbe, Hélène Celle, J. Beugnot
We demonstrate the potential of Brillouin distributed fiber sensor for the measurement of groundwater flow in an experimental site of Port Douvot close to the city of Besan¸con. The flow measurement is obtained by using active heating method based on heat pulse instrument. An industrial sensor cable with single mode fiber and multimode fiber was immersed on ground. We compare distributed Brillouin sensor reflectometry (BOTDR) and Analysis (BOTDA) on single mode fiber (SMF) and multimode optical fiber (MMF) with a spatial resolution of 1 m, a temperature resolution of 0.2 °C and an acquisition time of 1 min. These parameters are compatible with hydrology application. Active heating of borehole water in conjunction with fiber optic distributed temperature sensor measurements are realized. Contrary to Raman based distributed temperature sensor, Brillouin instrument allows measuring absolute temperature measurement and simplify the implementation on the setup. We demonstrate in this paper that Brillouin scattering based temperature sensor can be used for hydrogeology application.
{"title":"Distributed Brillouin optical fiber temperature sensor for groundwater flow measurement","authors":"M. Romanet, Alexandre Matic, M. Zerbib, K. Phan Huy, Jordan Labbe, Hélène Celle, J. Beugnot","doi":"10.1117/12.2679978","DOIUrl":"https://doi.org/10.1117/12.2679978","url":null,"abstract":"We demonstrate the potential of Brillouin distributed fiber sensor for the measurement of groundwater flow in an experimental site of Port Douvot close to the city of Besan¸con. The flow measurement is obtained by using active heating method based on heat pulse instrument. An industrial sensor cable with single mode fiber and multimode fiber was immersed on ground. We compare distributed Brillouin sensor reflectometry (BOTDR) and Analysis (BOTDA) on single mode fiber (SMF) and multimode optical fiber (MMF) with a spatial resolution of 1 m, a temperature resolution of 0.2 °C and an acquisition time of 1 min. These parameters are compatible with hydrology application. Active heating of borehole water in conjunction with fiber optic distributed temperature sensor measurements are realized. Contrary to Raman based distributed temperature sensor, Brillouin instrument allows measuring absolute temperature measurement and simplify the implementation on the setup. We demonstrate in this paper that Brillouin scattering based temperature sensor can be used for hydrogeology application.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125360292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Bruno, M. Janneh, S. Guardato, G. Donnarumma, G. Iannaccone, G. Gruca, S. Werzinger, A. Gunda, N. Rijnveld, A. Cutolo, M. Pisco, A. Cusano
We report on the development and field test of fiber optic hydrophones (FOHs). In details, we focused on the development of acoustic hydrophones for towed arrays applications and seismic hydrophones for seismological monitoring applications. In both cases, the sensing configuration is based on a Michelson interferometer where a fiber coil is wrapped around a compliant mandrel acting as a sensitive element. For the first application, acoustic hydrophones were characterized in an instrumented tank at Leonardo Finmeccanica premises. The hydrophone exhibited a responsivity of about 19 nm/Pa in the frequency range 3÷10 kHz with a resolution down to 300μPa /√Hz. The same FOHs were used as a basic building block to develop a towed array with five elements. By using the same enabling technology, but tailoring the physical and geometrical properties of hydrophones, we developed seismic hydrophones. The sensing system was integrated in the seismologic monitoring system and installed at Campi-Flegrei caldera. During the field trials, we detected several earthquakes occurred in the area and compared the results with a reference piezoelectric hydrophone. The seismic sequence was used to retrieve the sensor responsivity in the frequency range 1-80Hz. The sensing system exhibited a responsivity of about 300nm/Pa and an average noise floor level down to 100μPa/√Hz. The reported field trials demonstrated the capability of FOHs to operate in relevant environments and realistic scenarios.
{"title":"Fiber optic hydrophones for underwater monitoring","authors":"F. Bruno, M. Janneh, S. Guardato, G. Donnarumma, G. Iannaccone, G. Gruca, S. Werzinger, A. Gunda, N. Rijnveld, A. Cutolo, M. Pisco, A. Cusano","doi":"10.1117/12.2678297","DOIUrl":"https://doi.org/10.1117/12.2678297","url":null,"abstract":"We report on the development and field test of fiber optic hydrophones (FOHs). In details, we focused on the development of acoustic hydrophones for towed arrays applications and seismic hydrophones for seismological monitoring applications. In both cases, the sensing configuration is based on a Michelson interferometer where a fiber coil is wrapped around a compliant mandrel acting as a sensitive element. For the first application, acoustic hydrophones were characterized in an instrumented tank at Leonardo Finmeccanica premises. The hydrophone exhibited a responsivity of about 19 nm/Pa in the frequency range 3÷10 kHz with a resolution down to 300μPa /√Hz. The same FOHs were used as a basic building block to develop a towed array with five elements. By using the same enabling technology, but tailoring the physical and geometrical properties of hydrophones, we developed seismic hydrophones. The sensing system was integrated in the seismologic monitoring system and installed at Campi-Flegrei caldera. During the field trials, we detected several earthquakes occurred in the area and compared the results with a reference piezoelectric hydrophone. The seismic sequence was used to retrieve the sensor responsivity in the frequency range 1-80Hz. The sensing system exhibited a responsivity of about 300nm/Pa and an average noise floor level down to 100μPa/√Hz. The reported field trials demonstrated the capability of FOHs to operate in relevant environments and realistic scenarios.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123090559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Liao, Mengqiang Zou, Lei Xu, Y. Wang, Dejun Liu, Yiping Wang
Ultrasensitive nanomechanical instruments, e.g., atomic force microscopy (AFM), can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes. However, these instruments are limited because of their size and complex feedback system. Here, we demonstrate a miniature fiber optical nanomechanical probe (FONP) that can be used to detect the mechanical properties of single cells. The stiffness matching of the FONP and sample can be realized by customizing the microcantilever’s spring constant. As a proof-of concept, three FONPs with spring constants varying from 0.421 N/m to 52.6 N/m by more than two orders of magnitude were prepared. The Young's modulus of heterogeneous soft materials, such as polydimethylsiloxane, onion cells and MCF-7 cells, were successfully measured. FONP has made substantial progress in realizing basic biological discoveries, and our strategy provides a universal protocol for directly programming fiber-optic AFMs.
{"title":"Fiber optic nanomechanical probe for single-cell mechanics analysis","authors":"C. Liao, Mengqiang Zou, Lei Xu, Y. Wang, Dejun Liu, Yiping Wang","doi":"10.1117/12.2678308","DOIUrl":"https://doi.org/10.1117/12.2678308","url":null,"abstract":"Ultrasensitive nanomechanical instruments, e.g., atomic force microscopy (AFM), can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes. However, these instruments are limited because of their size and complex feedback system. Here, we demonstrate a miniature fiber optical nanomechanical probe (FONP) that can be used to detect the mechanical properties of single cells. The stiffness matching of the FONP and sample can be realized by customizing the microcantilever’s spring constant. As a proof-of concept, three FONPs with spring constants varying from 0.421 N/m to 52.6 N/m by more than two orders of magnitude were prepared. The Young's modulus of heterogeneous soft materials, such as polydimethylsiloxane, onion cells and MCF-7 cells, were successfully measured. FONP has made substantial progress in realizing basic biological discoveries, and our strategy provides a universal protocol for directly programming fiber-optic AFMs.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126502861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiaxin Li, Zhen Chen, Xin Cheng, H. Qu, C. Caucheteur, Xuehao Hu
In this work, we reported 2-mm-long fiber Bragg gratings (FBGs) in benzyl dimethyl ketal (BDK)-doped poly(methyl methacrylate) (PMMA) optical fibers by means of a 520 nm femtosecond laser and point-by-point FBG inscription technique. The highest reflectivity of ~99% is obtained with a pulse energy of 11.2 nJ, showing a large refractive index modulation amplitude of 7.2×10-4 .
{"title":"Bragg grating inscription in BDK-doped PMMA optical fiber using femtosecond laser point-by-point technique","authors":"Jiaxin Li, Zhen Chen, Xin Cheng, H. Qu, C. Caucheteur, Xuehao Hu","doi":"10.1117/12.2678415","DOIUrl":"https://doi.org/10.1117/12.2678415","url":null,"abstract":"In this work, we reported 2-mm-long fiber Bragg gratings (FBGs) in benzyl dimethyl ketal (BDK)-doped poly(methyl methacrylate) (PMMA) optical fibers by means of a 520 nm femtosecond laser and point-by-point FBG inscription technique. The highest reflectivity of ~99% is obtained with a pulse energy of 11.2 nJ, showing a large refractive index modulation amplitude of 7.2×10-4 .","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120969317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. A. Allousch, R. Crickmore, B. Marx, T. Jostmeier
We demonstrate Distributed Acoustic Sensing (DAS) with extended distance range utilising repeaterless all-optical amplification and single-side interrogation schemes. This work addresses the need for over 200 km range of distributed fibre-optic sensing in applications where very long assets need to be monitored, e.g., subsea power cable monito ring. A commercially available DAS interrogator and an advanced prototype interrogator setup with increased system performance are used. Both are based on coherent OTDR to detect Rayleigh backscattering. Range extension is achieved by compensating optical losses with amplifying the pulse traveling down the fibre as well as the Rayleigh backscattered signal coming back to the interrogator. We do this by launching CW pump light into the sensing fibre to create a combination of distributed Raman amplification and a remote optically pumped amplifier in an erbium doped fibre. We analyse the DAS interrogator’s ability to detect acoustic events at distances between 170 km and 200 km of ultra-low loss telecom fibres in a quantitative and linear way. To this end, events are simulated by periodically modulating the length of a short fibre at those distances with a piezo fibre stretcher. Results show that the thereby created optical phase shift is correctly measured and that amplitude and frequency of the applied signal are successfully reconstructed. It is thereby proven that singleended DAS is possible with the presented interrogators and all optical amplification schemes to achieve at least 200 km range.
{"title":"Extended range of repeaterless distributed acoustic sensing with coherent OTDR interrogators utilising optical amplification","authors":"M. A. Allousch, R. Crickmore, B. Marx, T. Jostmeier","doi":"10.1117/12.2678084","DOIUrl":"https://doi.org/10.1117/12.2678084","url":null,"abstract":"We demonstrate Distributed Acoustic Sensing (DAS) with extended distance range utilising repeaterless all-optical amplification and single-side interrogation schemes. This work addresses the need for over 200 km range of distributed fibre-optic sensing in applications where very long assets need to be monitored, e.g., subsea power cable monito ring. A commercially available DAS interrogator and an advanced prototype interrogator setup with increased system performance are used. Both are based on coherent OTDR to detect Rayleigh backscattering. Range extension is achieved by compensating optical losses with amplifying the pulse traveling down the fibre as well as the Rayleigh backscattered signal coming back to the interrogator. We do this by launching CW pump light into the sensing fibre to create a combination of distributed Raman amplification and a remote optically pumped amplifier in an erbium doped fibre. We analyse the DAS interrogator’s ability to detect acoustic events at distances between 170 km and 200 km of ultra-low loss telecom fibres in a quantitative and linear way. To this end, events are simulated by periodically modulating the length of a short fibre at those distances with a piezo fibre stretcher. Results show that the thereby created optical phase shift is correctly measured and that amplitude and frequency of the applied signal are successfully reconstructed. It is thereby proven that singleended DAS is possible with the presented interrogators and all optical amplification schemes to achieve at least 200 km range.","PeriodicalId":424244,"journal":{"name":"European Workshop on Optical Fibre Sensors","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121582910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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