The multiplexing ability of a novel multiplexing fiber Bragg grating （FBG） method based on Optical Time Domain Reflecto meter （OTDR） and Time Division Multiplexing TDM technologies has been theoretically analyzed ...The multiplexing ability of a novel multiplexing fiber Bragg grating （FBG） method based on Optical Time Domain Reflecto meter （OTDR） and Time Division Multiplexing TDM technologies has been theoretically analyzed and studied. This method permits the interrogation of hundreds of identical FBGs with low reflectivity in a single fiber, making the FBG sensors more applicable in the aerospace health monitoring engineering. The analysis shows that the multiplexing ability can be greatly improved if the FBG reflectivity is sufficiently low. And hence, an inexpensive large-scale distributed sensing system based on this method can be realized, When evaluating the multiplexing ability of this system, we propose for the first time that the interference effect of multi-reflections among FBGs should be taken into consideration.展开更多
A stable and broadband microwave photonic phase shifter based on the combined use of a linear chirped fiber Bragg grating and optical single-sideband （OSSB） modulation is proposed and experimentally demonstrated. Th...A stable and broadband microwave photonic phase shifter based on the combined use of a linear chirped fiber Bragg grating and optical single-sideband （OSSB） modulation is proposed and experimentally demonstrated. The quality of the radio frequency （RF） signal is improved by the spectral separation delay processing. The theoretical fundamentals of the scheme are explained and the phase shift can be controlled linearly by the wave- length of the light source. In the experiment, a full 360° phase shift with a 10 GHz bandwidth can be achieved and tuned dynamically, continuously, and stably.展开更多
Using transmitting volume Bragg gratings （TVBG） as a basis,an experiment on one-dimensional spatial filtering of a deformed laser beam is designed.The deformed laser beam results from a He-Ne laser beam modulated by...Using transmitting volume Bragg gratings （TVBG） as a basis,an experiment on one-dimensional spatial filtering of a deformed laser beam is designed.The deformed laser beam results from a He-Ne laser beam modulated by an amplitude modulation plate with a spatial frequency of 7.2 mm·1.Results show that when the central wave vector of the deformed beam satisfies the Bragg law of TVBG,the spatial profile of the -1st forward-diffracted order is similar to that of the undeformed He-Ne laser beam due to the TVBG with a spatial frequency selective bandwidth of less than 5.0 mm·1.The higher frequency components of the deformed beam are filtered out in the optical near field.Thus,the TVBG cleanup of the spatiallydeformed laser beam is realized experimentally.展开更多
A field-programmable gate array （FPGA）-based large-capacity sensing network with ultra-weak fiber Bragg gratings （FBGs） is proposed and experimentally studied. The demodulation system is constructed to interrogate...A field-programmable gate array （FPGA）-based large-capacity sensing network with ultra-weak fiber Bragg gratings （FBGs） is proposed and experimentally studied. The demodulation system is constructed to interrogate 1642 serial time-division-multiplexing FBGs with a peak refleetivity of about -40 dB and equal separations of 2.5 m. Two semiconductor optical amplifiers and an InGaAs linear sensor array controlled by an FPGA are introduced to the demodulation system to achieve fast, precise, and flexible interrogation. The low crosstalk and spectral distortion axe investigated through both theoretical analysis and experiments.展开更多
Regenerated gratings seeded by type-I gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other ...Regenerated gratings seeded by type-I gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature （UHT） gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.展开更多
We report on a widely tunable, narrow linewidth operation ofa Tm：YAG ceramic laser. A volume Bragg grating is used in the cavity as a folding mirror for wavelength selection. The wavelength is tuned from 1956.2 to 19...We report on a widely tunable, narrow linewidth operation ofa Tm：YAG ceramic laser. A volume Bragg grating is used in the cavity as a folding mirror for wavelength selection. The wavelength is tuned from 1956.2 to 1995 nm, leading to a total tuning range of 38.7 nm. The linewidth is around 0.1 nm over the whole tuning range. A maximum output power of 1.51 W at 1990.5 nm is achieved at 37.8 W absorbed pump power. Different saturation behaviors are observed in the laser performances at different wavelengths.展开更多
The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolym...The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolymer. Diffraction efficiency of a single grating is up to 78% in Bragg＇s condition, then a two-dimensional non-spatial filter, which consists of two volume Bragg gratings and a half-wave plate, enables the laser beam filtered in two dimensions with the diffraction efficiency of 54%. The Bragg＇s condition and effect of polarisation on performances of the two-dimension filter are also discussed.展开更多
Diffraction efficiency of volume Bragg grating, whose period is in the same order as the incident wavelength, is related to the polarization direction of the incident linear polarized beam. When two linearly polarized...Diffraction efficiency of volume Bragg grating, whose period is in the same order as the incident wavelength, is related to the polarization direction of the incident linear polarized beam. When two linearly polarized recording beams with the same polarization direction are used for recording volume Bragg gratings in a photopolymer with diffusion amplification, the azimuth of polarization of the reconstruction beam influences the diffraction efficiency of the grating. When the probe beam is linearly polarized and oriented orthogonally to the grating vectors, the ±1-order diffraction beams are also linearly polarized with polarization direction parallel to that of the probe beam. According to the results, a two-dimensional nonspatial optical filter consisting of the volume Bragg gratings would achieve significantly higher efficiency.展开更多
Efficient writing of Bragg gratings in 12-ring highly-nonlinear photonie crystal fibers is described. Experimental and numerical investigations are performed to reveal the optimum angle for coupling UV writing light t...Efficient writing of Bragg gratings in 12-ring highly-nonlinear photonie crystal fibers is described. Experimental and numerical investigations are performed to reveal the optimum angle for coupling UV writing light to the core. Furthermore, we show that the formation of a strongly briefringent grating is at a particular angle of orientation.展开更多
This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are...This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are computed by taking overlap integration. Numerical results for uniform gratings, phase-shifted gratings and grating cavities as well as electro-optic tunable gratings are presented. These integrated As2S3 sidewall gratings on LiNbO3 substrate provide an approach to the design of a wide range of integrated optical devices including switches, laser cavities, modulators, sensors and tunable filters.展开更多
基金Foundation item： National Natural Science Foundation of China （10376001）
文摘The multiplexing ability of a novel multiplexing fiber Bragg grating （FBG） method based on Optical Time Domain Reflecto meter （OTDR） and Time Division Multiplexing TDM technologies has been theoretically analyzed and studied. This method permits the interrogation of hundreds of identical FBGs with low reflectivity in a single fiber, making the FBG sensors more applicable in the aerospace health monitoring engineering. The analysis shows that the multiplexing ability can be greatly improved if the FBG reflectivity is sufficiently low. And hence, an inexpensive large-scale distributed sensing system based on this method can be realized, When evaluating the multiplexing ability of this system, we propose for the first time that the interference effect of multi-reflections among FBGs should be taken into consideration.
基金supported by the National "973" Program of China(No.2012CB315604)the Natural Science Foundation of China(Nos.61575028 and 61331008)+2 种基金the Program for New Century Excellent Talents in University(No.NCET-12-0793)the Beijing Nova Program (No.2011065)the Open Fund of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)
文摘A stable and broadband microwave photonic phase shifter based on the combined use of a linear chirped fiber Bragg grating and optical single-sideband （OSSB） modulation is proposed and experimentally demonstrated. The quality of the radio frequency （RF） signal is improved by the spectral separation delay processing. The theoretical fundamentals of the scheme are explained and the phase shift can be controlled linearly by the wave- length of the light source. In the experiment, a full 360° phase shift with a 10 GHz bandwidth can be achieved and tuned dynamically, continuously, and stably.
基金supported by the NSAF Foundation of the National Natural Science Foundation of China and the Chinese Academy of Engineering Physics (CAEP)under Grant No.10676038
文摘Using transmitting volume Bragg gratings （TVBG） as a basis,an experiment on one-dimensional spatial filtering of a deformed laser beam is designed.The deformed laser beam results from a He-Ne laser beam modulated by an amplitude modulation plate with a spatial frequency of 7.2 mm·1.Results show that when the central wave vector of the deformed beam satisfies the Bragg law of TVBG,the spatial profile of the -1st forward-diffracted order is similar to that of the undeformed He-Ne laser beam due to the TVBG with a spatial frequency selective bandwidth of less than 5.0 mm·1.The higher frequency components of the deformed beam are filtered out in the optical near field.Thus,the TVBG cleanup of the spatiallydeformed laser beam is realized experimentally.
文摘A field-programmable gate array （FPGA）-based large-capacity sensing network with ultra-weak fiber Bragg gratings （FBGs） is proposed and experimentally studied. The demodulation system is constructed to interrogate 1642 serial time-division-multiplexing FBGs with a peak refleetivity of about -40 dB and equal separations of 2.5 m. Two semiconductor optical amplifiers and an InGaAs linear sensor array controlled by an FPGA are introduced to the demodulation system to achieve fast, precise, and flexible interrogation. The low crosstalk and spectral distortion axe investigated through both theoretical analysis and experiments.
基金supported by the Australian Research Council (ARC) Discovery Project.
文摘Regenerated gratings seeded by type-I gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature （UHT） gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.
基金supported by the National Natural Science Foundation of China(Grant Nos.61177045,61308047,and 11274144)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions
文摘We report on a widely tunable, narrow linewidth operation ofa Tm：YAG ceramic laser. A volume Bragg grating is used in the cavity as a folding mirror for wavelength selection. The wavelength is tuned from 1956.2 to 1995 nm, leading to a total tuning range of 38.7 nm. The linewidth is around 0.1 nm over the whole tuning range. A maximum output power of 1.51 W at 1990.5 nm is achieved at 37.8 W absorbed pump power. Different saturation behaviors are observed in the laser performances at different wavelengths.
基金supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (NSAF) (Grant No. 10676038)
文摘The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolymer. Diffraction efficiency of a single grating is up to 78% in Bragg＇s condition, then a two-dimensional non-spatial filter, which consists of two volume Bragg gratings and a half-wave plate, enables the laser beam filtered in two dimensions with the diffraction efficiency of 54%. The Bragg＇s condition and effect of polarisation on performances of the two-dimension filter are also discussed.
基金supported by the National Natural Science Foundation of China(No.10676038)the China Academy of Engineering Physics(CAEP)
文摘Diffraction efficiency of volume Bragg grating, whose period is in the same order as the incident wavelength, is related to the polarization direction of the incident linear polarized beam. When two linearly polarized recording beams with the same polarization direction are used for recording volume Bragg gratings in a photopolymer with diffusion amplification, the azimuth of polarization of the reconstruction beam influences the diffraction efficiency of the grating. When the probe beam is linearly polarized and oriented orthogonally to the grating vectors, the ±1-order diffraction beams are also linearly polarized with polarization direction parallel to that of the probe beam. According to the results, a two-dimensional nonspatial optical filter consisting of the volume Bragg gratings would achieve significantly higher efficiency.
文摘Efficient writing of Bragg gratings in 12-ring highly-nonlinear photonie crystal fibers is described. Experimental and numerical investigations are performed to reveal the optimum angle for coupling UV writing light to the core. Furthermore, we show that the formation of a strongly briefringent grating is at a particular angle of orientation.
文摘This paper introduces the design and applications of integrated As2S3 sidewall Bragg gratings on LiNbO3 substrate. The grating reflectance and bandwidth are analyzed with coupled-mode theory. Coupling coefficients are computed by taking overlap integration. Numerical results for uniform gratings, phase-shifted gratings and grating cavities as well as electro-optic tunable gratings are presented. These integrated As2S3 sidewall gratings on LiNbO3 substrate provide an approach to the design of a wide range of integrated optical devices including switches, laser cavities, modulators, sensors and tunable filters.
