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Ag-coated Long-period Fiber Grating 被引量:2
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作者 GU Zheng-tian XU Yan-ping CHEN Jia-bi 《Semiconductor Photonics and Technology》 CAS 2005年第3期203-207,211,共6页
Based on coupled-mode theo ry , the eigenvalue equation of five-layered long-period fiber grating(LPFG) sens or with Ag film and gas-sensitive film overlays are firstly studied. The probl em of resolving complex eigen... Based on coupled-mode theo ry , the eigenvalue equation of five-layered long-period fiber grating(LPFG) sens or with Ag film and gas-sensitive film overlays are firstly studied. The probl em of resolving complex eigenvalue equation on five-layered LPFG is analyzed, a nd the method of resolution is also given. Then the eigenvalue equation of three -layered metal cladding LPFG is analyzed, and the complex transcendental equati on is also discussed. The computing result shows that the coupling between the l ow-order EH modes and the core mode is much stronger than that between the low -order HE modes and the core mode. 展开更多
关键词 long-period fiber grating Gas sensors Metal cladding Complex eigenvalue equation
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Fabrication of long-period fiber gratings by CO_2 laser in fiber under tension 被引量:1
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作者 刘云启 涂文涛 +1 位作者 杨丹 王廷云 《Journal of Shanghai University(English Edition)》 CAS 2011年第1期1-6,共6页
We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings (LPFGs) in single-mode fiber (SMF) under tension. New transmission dips can be generated due to the frozen-in stress in the... We demonstrate experimentally fabrication of CO2 laser written long-period fiber gratings (LPFGs) in single-mode fiber (SMF) under tension. New transmission dips can be generated due to the frozen-in stress in the fiber under tension. Dynamics analysis of laser writing process is performed to study the mechanism of the grating inscription. Experimental results show that the wavelength shift of new generated resonance dips can shift towards the longer or shorter wavelength with the increase of laser scanning cycles for gratings with different pitches. 展开更多
关键词 long-period fiber grating (LPFG) frozen-in viscoelasticity writing dynamics analysis asymmetric index distribution
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Convention of Optical Vortices in Two-Helix Long-Period Fiber Gratings
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作者 张晓强 陈瑞山 +2 位作者 周勇 明海 王安廷 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期45-48,共4页
An effective method to fabricate two-helix long-period fiber gratings (TH-LFGs) is presented. Based on the coupling mode theory, the conversion of optical vortices (OVs) in TH-LFGs are analyzed in detail. The conv... An effective method to fabricate two-helix long-period fiber gratings (TH-LFGs) is presented. Based on the coupling mode theory, the conversion of optical vortices (OVs) in TH-LFGs are analyzed in detail. The conversions of OVs with different topological charges: 0 → ±2 and 1 → 3 are simulated as three examples and the conversion efficiency higher than 98% can be realized. 展开更多
关键词 of on OAM Convention of Optical Vortices in Two-Helix long-period fiber gratings MODE IS in
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Hybrid Long-Period Fiber Grating with Multimode Fiber Core for Refractive Index Measurement
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作者 邵敏 乔学光 +1 位作者 任学良 杨德兴 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第11期41-44,共4页
A refractive index (RI) sensor based on hybrid long-period fiber grating (LPFG) with multimode fiber core (MMFC) is proposed and demonstrated. The surrounding RI can be determined by monitoring the separation be... A refractive index (RI) sensor based on hybrid long-period fiber grating (LPFG) with multimode fiber core (MMFC) is proposed and demonstrated. The surrounding RI can be determined by monitoring the separation between the resonant wavelengths of the LPFG and MMFC since the resonant wavelengths of the LPFG and MMFC will shift in opposite directions when the surrounding RI changes. Experimental results show that the sensor possesses an enhanced sensitivity of 526.92nm/RIU in the RI range of 1.387-1.394 RIU. The response to the temperature is also discussed. 展开更多
关键词 Hybrid long-period fiber grating with Multimode fiber Core for Refractive Index Measurement RIU
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Sensing characteristics of a metal film coated long-period fiber grating
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作者 WANG Yan LIU Jia-ping +2 位作者 LIU Ji-hong HU Xing-liu FANG Ting 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2017年第1期89-96,共8页
To obtain the influence rules of the coating parameters of a long-period fiber grating(LPFG)with respect to temperature,strain and refractive index sensing properties,based on the mode coupling theory,a strict four-la... To obtain the influence rules of the coating parameters of a long-period fiber grating(LPFG)with respect to temperature,strain and refractive index sensing properties,based on the mode coupling theory,a strict four-layer theorietical model of a metal film coated LPFG is established,and these parameters that affect the spectral characteristics of the metal film coated LPFG are studied.The simulation results show that there is an optimal metal film thickness on the surface of the LPFG that will induce the surface-plasmon resonance(SP R)effect,which results in higher sensitivity to the environmental temperature and refractive index but has little influence on the strain There is theoretical evidence that when the silver thickness is between0.8and1.2nm,the refractive index sensitivity will reach the peak point of42.4026,at which the refractive index sensor sensitivity is increased by4.S%.The theoretical results of coating a long-period fiber grating provide a good theoretical basis and guidance for LPFG design and parameters optimization 展开更多
关键词 metal film coated long-period fiber grating (L P FG ) surface plasmon resonance (SP R ) transmission spectrum sensing characteristics
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Vector bending sensor based on chirped long-period grating with off-axis micro-helix taper
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作者 周健 何学兰 +4 位作者 陈宏洲 熊子洋 杨菁 关春颖 苑立波 《Chinese Optics Letters》 SCIE EI CAS CSCD 2023年第6期36-42,共7页
Vector bending sensing has been consistently growing in many fields.A low-cost and high sensitivity vector bending sensor based on a chirped long-period fiber grating[LPFG]with an off-axis micro helix taper is propose... Vector bending sensing has been consistently growing in many fields.A low-cost and high sensitivity vector bending sensor based on a chirped long-period fiber grating[LPFG]with an off-axis micro helix taper is proposed and experimentally demonstrated.The grating is composed of several sections of single-mode fiber with gradually larger lengths,and the off-axis micro helix tapers with fixed lengths when they are fabricated by using the arc discharge technology.The large refractive index modulation in the micro-helix taper greatly reduces the sensor size.The total length of the sensor is only 4.67 mm.The micro-helix taper-based LPFG can identify the bending direction due to the asymmetric structure introduced by the micro helix.The experimental results show that the transmission spectra of the sensor have distinct responses for different bending directions,and the maximum bending sensitivity is 14.08 nm/m^(-1)in the range from 0.128 m^(-1)to 1.28 m^(-1).The proposed bending sensor possesses pronounced advantages,such as high sensitivity,small size,low cost,and orientation identification,and offers a very promising method for bend measurement. 展开更多
关键词 bending sensor chirped long-period fiber grating off-axis micro helix taper orientation identification
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Highly sensitive torsion sensor based on triangular-prism-shaped long-period fiber gratings 被引量:3
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作者 Senyu Wang Yiwei Ma +8 位作者 Xiaoyang Li Yang Yi Cuiting Sun Jingyu Lin Chengguo Tong Yuxiang Li Tao Geng Weimin Sun Libo Yuan 《Chinese Optics Letters》 SCIE EI CAS CSCD 2021年第4期28-31,共4页
We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity.This sensor is configured by a triangular-prism-shaped long-period fiber gr... We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity.This sensor is configured by a triangular-prism-shaped long-period fiber grating,which is fabricated by the high frequency CO_(2) laser polished method.The unique design of the triangular-shaped structure breaks the rotational symmetry of the optical fiber and provides high sensitivity for torsion measurement.In preliminary experiments,the torsion response of the sensor achieves a good stability and linearity.The torsion sensitivity is 0.54 nm/(rad/m),which renders the proposed structure a highly sensitive torsion sensor. 展开更多
关键词 long-period fiber grating torsion sensor CO_(2)laser etched method
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Utilizing phase-shifted long-period fiber grating to suppress spectral broadening of a high-power fiber MOPA laser system 被引量:2
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作者 Yinxu Bian Kerong Jiao +3 位作者 Xuecheng Wu Hua Shen Feiyan Yang Rihong Zhu 《High Power Laser Science and Engineering》 SCIE CAS CSCD 2021年第3期33-39,共7页
Suppressing nonlinear effects in high-power fiber lasers based on fiber gratings has become a hotspot.At present,research is mainly focused on suppressing stimulated Raman scattering in a high-power fiber laser.Howeve... Suppressing nonlinear effects in high-power fiber lasers based on fiber gratings has become a hotspot.At present,research is mainly focused on suppressing stimulated Raman scattering in a high-power fiber laser.However,the suppression of spectral broadening,caused by self-phase modulation or four-wave mixing,is still a challenging attribute to the close distance between the broadened laser and signal laser.If using a traditional fiber grating with only one stopband to suppress the spectral broadening,the signal power will be stripped simultaneously.Confronting this challenge,we propose a novel method based on phase-shifted long-period fiber grating(PS-LPFG)to suppress spectral broadening in a high-power fiber master oscillator power amplifier(MOPA)laser system in this paper.A PS-LPFG is designed and fabricated on 10/130 passive fiber utilizing a point-by-point scanning technique.The resonant wavelength of the fabricated PS-LPFG is 1080 nm,the full width at half maximum of the passband is 5.48 nm,and stopband extinction exceeds 90%.To evaluate the performance of the PS-LPFG,the grating is inserted into the seed of a kilowattlevel continuous-wave MOPA system.Experiment results show that the 30 dB linewidth of the output spectrum is narrowed by approximately 37.97%,providing an effective and flexible way for optimizing the output linewidth of highpower fiber MOPA laser systems. 展开更多
关键词 fiber optics component high-power fiber laser nonlinear effects phase-shifted long-period fiber grating spectral broadening
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Characterization of external refractive index sensitivity of a photonic crystal fiber long-period grating 被引量:3
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作者 Fei Tian Jiri Kanka Henry Du 《Chinese Optics Letters》 SCIE EI CAS CSCD 2015年第7期45-47,共3页
Long-period gratings (LPGs) are fabricated in a photonic crystal fiber (PCF) using the symmetric point- by-point CO2 laser irradiation method to explore the sensitivity characterization of PCF-LPG. Numerical sim- ... Long-period gratings (LPGs) are fabricated in a photonic crystal fiber (PCF) using the symmetric point- by-point CO2 laser irradiation method to explore the sensitivity characterization of PCF-LPG. Numerical sim- ulation is used to guide the investigation. It is found that the refractive index (RI) sensitivity of PCF-LPG depends on the coupled cladding modes as well as the coupled resonance wavelength (RW) of the LPG. Experimental studies show that the longer the RW, the higher the RI sensitivity for the same cladding mode. At similar RWs, the lower the cladding mode, the higher the RI sensitivity of PCF-LPG. 展开更多
关键词 PCF LPG Characterization of external refractive index sensitivity of a photonic crystal fiber long-period grating
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Intensity detecting refractive index sensors with long-period fiber gratings written in STS structure 被引量:1
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作者 Zuliang Ruan Li Pei +4 位作者 Jingjing Zheng Jianshuai Wang Liangying Wu Tigang Ning Ji Wang 《Chinese Optics Letters》 SCIE EI CAS CSCD 2019年第7期12-16,共5页
A refractive index intensity detecting sensor with long-period grating written in the single-mode–thin-core–single-mode fiber(STS) structure is proposed and optimized theoretically.The sensor is composed of two sing... A refractive index intensity detecting sensor with long-period grating written in the single-mode–thin-core–single-mode fiber(STS) structure is proposed and optimized theoretically.The sensor is composed of two single-mode fibers connected by a section of long-period fiber grating fabricated on thin-core fiber.After optimization and benefitting from the phase matching point, the loss peak of the structure can reach 62.8dB theoretically.The wavelength of the characteristic peak is fixed at the phase matching point, so intensity detection can be achieved.The sensitivity can reach 272.5dB/RIU.The structural optimization in this Letter provides a reference for the fabrication of an easy-made all-fiber sensor without extra cladding. 展开更多
关键词 long-period fiber gratingS WRITTEN INDEX INTENSITY detecting sensor
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A new phase-shifted long-period fiber grating for simultaneous measurement of torsion and temperature 被引量:1
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作者 Cuiting Sun Ran Wang +10 位作者 Xiren Jin Zemin Wang Weiliang Liu Shuo Zhang Yiwei Ma Jingyu Lin Yue Li Tao Geng Weimin Sun Zhongquan Qu Libo Yuan 《Chinese Optics Letters》 SCIE EI CAS CSCD 2020年第2期39-43,共5页
A novel phase-shifted long-period fiber grating(PS-LPFG)for the simultaneous measurement of torsion and temperature is described and experimentally demonstrated.The PS-LPFG is fabricated by inserting a pretwisted stru... A novel phase-shifted long-period fiber grating(PS-LPFG)for the simultaneous measurement of torsion and temperature is described and experimentally demonstrated.The PS-LPFG is fabricated by inserting a pretwisted structure into the long-period fiber grating(LPFG)written in single-mode fiber(SMF).Experimental results show that the torsion sensitivities of the two dips are?0.114 nm/(rad/m)and?0.069 nm/(rad/m)in the clockwise direction,and?0.087 nm/(rad/m)and?0.048 nm/(rad/m)in the counterclockwise direction,respectively.The temperature sensitivities of the two dips are 0.057 nm/℃ and 0.051 nm/℃,respectively.The two dips of the PS-LPFG exhibit different responses to torsion and temperature.Simultaneous measurement of torsion and temperature can be implemented using a sensor.The feasibility and stabilization of simultaneous torsion and temperature measurement have been confirmed,and hence this novel PS-LPFG demonstrates potential for fiber sensing and engineering applications. 展开更多
关键词 phase-shifted long-period fiber grating pre-twisted structure SINGLE-MODE fiber SIMULTANEOUS measurement TORSION temperature
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Optical Sensing Based on Light Coupling Between Two Parallel Long-Period Fiber Gratings 被引量:1
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作者 Kin Seng CHIANG Yunqi LIU +1 位作者 Qing LIU Yunjiang RAO 《Photonic Sensors》 SCIE EI CAS 2011年第3期204-209,共6页
A new optical intensity-based sensing mechanism for the measurement of refractive index and minute displacement is proposed in this paper, which is based on modifying the amount of light coupled between two parallel l... A new optical intensity-based sensing mechanism for the measurement of refractive index and minute displacement is proposed in this paper, which is based on modifying the amount of light coupled between two parallel long-period fiber gratings. The characteristics of this sensing mechanism with experiments and simulation results are demonstrated. 展开更多
关键词 long-period fiber grating optical fiber sensor refractive-index sensor displacement sensor intensity-based sensor
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Dual-channel microfluidic sensor based on side-hole fiber with two long-period fiber gratings
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作者 Yu Zhang Yongzhi Li +6 位作者 Chao Liu Zhihai Liu Yaxun Zhang Xinghua Yang Jianzhong Zhang Jun Yang Libo Yuan 《Chinese Optics Letters》 SCIE EI CAS CSCD 2020年第2期1-4,共4页
We propose and demonstrate a dual-channel microfluidic sensor based on a side-hole fiber(SHF)with two longperiod fiber grating(LPFG)structures.There are two air holes in the SHF,which are natural microfluidic channels... We propose and demonstrate a dual-channel microfluidic sensor based on a side-hole fiber(SHF)with two longperiod fiber grating(LPFG)structures.There are two air holes in the SHF,which are natural microfluidic channels.We fabricate two LPFGs(long-period gratings LPG-A and LPG-B)in the SHF with the resonance wavelengths of 1268.7 nm and 1385.8 nm,respectively.Results show that the refractive index sensitivities of LPG-A and LPG-B are?76.0 nm/RIU and?71.1 nm/RIU,respectively.One can measure the refractive index of liquid samples in two channels simultaneously.The proposed dual-channel microfluidic sensor has advantages of good linearity response,fluidic technology compatibility,and easy light input/output coupling and system integration,which helps the sensor to have a potential application in environmental detection and food safety detection. 展开更多
关键词 long-period grating OPTICAL fiber SENSOR refractive INDEX measurement
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Effects Of Average Index Variation in Apodized Long-Period Fiber Gratings
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作者 Yanju GU Kin Seng CHIANG 《Photonic Sensors》 SCIE EI CAS 2013年第2期102-111,共10页
We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating (LPFG) by the transfer matrix method and study how these effects depend on the gra... We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating (LPFG) by the transfer matrix method and study how these effects depend on the grating length, the grating profile, the modal dispersion factor, and the duty cycle of the index modulation. Apart from shifting the resonance wavelength and modifying the rejection band, average index variation can give rise to significant side lobes that may appear on the short-wavelength or long-wavelength side of the rejection band, depending on the signs of the average index change and the modal dispersion factor. Our results provide general guidance for the writing of LPFGs for the minimization of side lobes. Our analysis compares well with published experimental results and should be useful for the design and fabrication of LPFGs. 展开更多
关键词 APODIZATION fiber grating long-period fiber grating (LPFG) optical fiber sensor optical filter transfer matrix method
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Coupled Mode Characteristics From the Perturbation of 3D Printed Long-Period Fiber Grating Devices
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作者 Ravivudh KHUN-IN Yuji USUDA +2 位作者 Yuttapong JIRARAKSOPAKUN Apichai BHATRANAND Hideki YOKOI 《Photonic Sensors》 SCIE EI CSCD 2020年第3期195-203,共9页
Characteristics of electric field from a coupled mode inside an optical fiber under perturbation by three-dimensional(3D)printed long-period fiber grating(LPFG)device have been observed in this work by the experiment ... Characteristics of electric field from a coupled mode inside an optical fiber under perturbation by three-dimensional(3D)printed long-period fiber grating(LPFG)device have been observed in this work by the experiment and simulation.The various periodic index differences referring to the weights of perturbation by 3D printed LPFG device are applied on the single-mode fiber.The experimental results show that the resonant wavelength shift is a linear function of the grating period with the maximum coefficient of determination R2 of 0.9995.Some of resonant wavelengths are chosen to run simulations to investigate the electric field distribution.The scattering direction of the electric field states the magnitude of leaking optical power when the light transmits through the grating region applied to the single-mode fiber.Both the experimental and simulation results demonstrate that our proposed scheme can usefully be applied to selective tunable filters,intruder sensors,etc. 展开更多
关键词 3D printed long-period fiber grating device PERTURBATION resonant wavelength electric field distribution
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Novelty Design in Gain Flattening Filter of ASE Source Based on Fat Ultra-Long Period Fiber Grating 被引量:1
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作者 Fereshteh Mohammadi NAFCHI Sharifeh SHAHI +2 位作者 Mohammad Taha SHAFFAATIFAR Mohammad KANANI Hossein NOORMOHAMMADI 《Photonic Sensors》 SCIE EI CAS CSCD 2016年第3期243-248,共6页
A new type of gain flattening filter for amplified spontaneous emission (ASE) source based on erbium doped fiber (EDF) is proposed and demonstrated by fabricating and writing two series ultra-long period fiber gra... A new type of gain flattening filter for amplified spontaneous emission (ASE) source based on erbium doped fiber (EDF) is proposed and demonstrated by fabricating and writing two series ultra-long period fiber grating (ULPFG) on single mode fiber (SMF-28). The novelty method in this research is based on writing the two ULPFGs as fat gratings. The LPG is written by a simple and available arc-discharge method. The pump power based on single-pass backward pump configuration is around 100mW, and the average wavelength is near to 974nm. The gain flattening profile is obtained by 3.4 (±1.7)dB ripple in the wavelength range between 1524nm and 1565nm with 41-nm band width. 展开更多
关键词 Amplified spontaneous emission (ASE) source erbium-doped fiber amplifier (EDFA) gain flatteningfilter long-period fiber grating (LPFG)
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Characteristic control of long period fiber grating (LPFG) fabricated by infrared femtosecond laser 被引量:1
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作者 Xiaoyan SUN Peng HUANG +4 位作者 Jiefeng ZHAO Li WEI Nan ZHANG Dengfeng KUANG Xiaonong ZHU 《Frontiers of Optoelectronics》 2012年第3期334-340,共7页
Long period fiber gratings (LPFGs) with different spectral characteristics were fabricated with 1 kHz, 50 fs laser pulses. The contrast of resonant rejection band can be significantly increased by a proper amount of... Long period fiber gratings (LPFGs) with different spectral characteristics were fabricated with 1 kHz, 50 fs laser pulses. The contrast of resonant rejection band can be significantly increased by a proper amount of axial stress along a fiber during laser writing or post- processing with lower energy density laser irradiation. Variations of focal condition, pulse energy of laser irradiation and the number of grating periods lead to the generation of resonance rejection band of LPFGs from single-peak to multi-peak plus larger out-of-band loss. The out-of-band loss is primarily caused by Mie scattering from the laser processed cites, and it can be reduced by decreasing the duty cycle of grating pitch instead of lowing down the actual power of laser irradiation. 展开更多
关键词 long-period fiber grating (LPFG) infraredfemtosecond laser out-of-band loss Mie scattering micro-nano-fabrication
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Long Period Gratings in Photonic Crystal Fibers
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作者 Jian JU Wei JIN 《Photonic Sensors》 SCIE EI CAS 2012年第1期65-70,共6页
The authors review the recent advances in fabricating long-period gratings (LPGs) in photonic crystal fibers (PCFs). The novel light-guiding properties of the PCFs allow the demonstration of novel sensors and devi... The authors review the recent advances in fabricating long-period gratings (LPGs) in photonic crystal fibers (PCFs). The novel light-guiding properties of the PCFs allow the demonstration of novel sensors and devices based on such LPGs. The sensitivity of these PCF LPGs to temperature, strain and refractive index is discussed and compared with LPGs made on conventional single-mode fibers. In-fiber devices such as tunable band rejection filters, Mach-Zehnder interferometers are discussed. 展开更多
关键词 Photonic crystal fiber long-period grating optical fiber sensor
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