A chirped fibre Bragg grating according to ITU-T suggested L-band （2nd channel λ1 = 1570.83 nm; 80th channel λ2 = 1603.57 nm） with more than 1800 ps/nm single channel dispersion compensation is presented in this p...A chirped fibre Bragg grating according to ITU-T suggested L-band （2nd channel λ1 = 1570.83 nm; 80th channel λ2 = 1603.57 nm） with more than 1800 ps/nm single channel dispersion compensation is presented in this paper, of which the cladding mode loss, the delay curve ripple and the power fluctuation of the reflected spectrum are less than 0.5 dB, 50 ps and 0.25 dB, respectively. With this new FBG as dispersion compensation device, a 2 × 10 Gb/s wavelength division multiplexing （WDM） L-band transmission of 600 km based on conventional single mode fibre （G.652 fibre） is performed without forward error correction. The bit error rate （BER） is less than 10-12 and the power penalties of the 2nd and 80th channel of L-band are 1.8 dB and 2.0 dB, respectively.展开更多
In this paper,we propose the novel system of multipoint measurement.The sensors of measurements are chirped Bragg grating and the interrogation of sensors is sub-carrier phase.The wavelength division multiplexing tech...In this paper,we propose the novel system of multipoint measurement.The sensors of measurements are chirped Bragg grating and the interrogation of sensors is sub-carrier phase.The wavelength division multiplexing technique is used for addressing a network of FBG sensors and the time-division multiplexing technique is used for multipoint measurements.In the system,the modulation frequency of 200 MHz is adopted.The range of dectetion is from 0 to 900μεand the resolution is 12με. The time of the sensor response is about 1ns.展开更多
Based on the general theory of linear Chirped Bragg fiber grating, this paper discusses some parameters including different chirped values and quasi gauss coupling function relating with the reflectivity coefficient d...Based on the general theory of linear Chirped Bragg fiber grating, this paper discusses some parameters including different chirped values and quasi gauss coupling function relating with the reflectivity coefficient dispersion compensation.The result shows that selecting larger chirped value and appropriate qusi guass coupling function can improve the dispersion compensation while ensuring high reflectivity. The concept of "figure of merit" in the microwave field is introduced to quantize the equalizing power of the dispersion compensator.展开更多
We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg gratin...We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.展开更多
Optical chaos has attracted widespread attention owing to its complex dynamic behaviors.However,the time delay signature(TDS)caused by the external cavity mode reduces the complexity of optical chaos.We propose and nu...Optical chaos has attracted widespread attention owing to its complex dynamic behaviors.However,the time delay signature(TDS)caused by the external cavity mode reduces the complexity of optical chaos.We propose and numerically demonstrate the critical dispersion of chirped fiber Bragg grating(CFBG)for eliminating the TDS of laser chaos in this work.The critical dispersion,as a function of relaxation frequency and bandwidth of the optical spectrum,is found through extensive dynamics simulations.It is shown that the TDS can be eliminated when the dispersion of CFBG is above this critical dispersion.In addition,the influence of dispersive feedback light and output light from a laser is investigated.These results provide important quantitative guidance for designing chaotic semiconductor lasers without TDS.展开更多
Using the matrix approach,we analyzed the relation between the location of the transmission in stop band and the phase shift,and discussed the problem of varying the bandwidth of the transmission window.These theoreti...Using the matrix approach,we analyzed the relation between the location of the transmission in stop band and the phase shift,and discussed the problem of varying the bandwidth of the transmission window.These theoretical results in this paper have important significance for actual application of the phase-shifted fiber grating.展开更多
2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to ...2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.展开更多
Temperature and strain characteristics of uniform fibre grating with tapered metal coatings have been analysed theoretically, by which adjustable chirp characteristics of such gratings are shown. Electroplating is ado...Temperature and strain characteristics of uniform fibre grating with tapered metal coatings have been analysed theoretically, by which adjustable chirp characteristics of such gratings are shown. Electroplating is adopted to fabricate such gratings, and the tapered metal coating is obtained by gradually drawing the fibre grating out of the solution during the process of electroplating. The gradually changing cross-sectional area of the metal coating is calculated by a newly suggested numerical method. By combining the theoretical and numerical simulation analyses, the gratings＇ characteristics are given at various temperatures and strains. The results obtained using such a method are also testified by experiments.展开更多
Chirped fibre Bragg gratings （CFBGs） are required to be concatenated to compensate the fibre dispersion in the dense wavelength-division multiplexing （DWDM） systems. When the channel spacing is small, the performa...Chirped fibre Bragg gratings （CFBGs） are required to be concatenated to compensate the fibre dispersion in the dense wavelength-division multiplexing （DWDM） systems. When the channel spacing is small, the performance of CFBGs is degraded, which restricts the usage of fibre gratings. The origin of the interactions between the gratings is analysed and methods of suppressing the interactions are also proposed.展开更多
Suppression of stimulated Raman scattering(SRS)by means of chirped and tilted fiber Bragg gratings(CTFBGs)has become a key topic.However,research on high-power systems is still lacking due to two problems.Firstly,afte...Suppression of stimulated Raman scattering(SRS)by means of chirped and tilted fiber Bragg gratings(CTFBGs)has become a key topic.However,research on high-power systems is still lacking due to two problems.Firstly,after the inscription,there are a large number of hydroxyl compounds and hydrogen molecules in CTFBGs that cause significant heating due to their strong infrared absorption.Secondly,CTFBGs can couple Stokes light from the core to the cladding and the coating,which causes serious heating in the coating of the CTFBG.Aimed at overcoming these bottlenecks,a process that combines constant-low-temperature and variable-high-temperature annealing is used to reduce the thermal slope of the CTFBG.Also,a segmented-corrosion cladding power stripping technology is used on the CTFBG to remove the Stokes light which is coupled to the cladding,which solves the problem of overheating in the coating of the CTFBG.Thereby,a CTFBG with both a kilowatt-level power-carrying load and the ability to suppress SRS in a fiber laser has been developed.Further,we establish a kW-level CW oscillator to test the CTFBG.Experimental results demonstrate that the power-carrying load of the CTFBG is close to 1 kW,the thermal slope is lower than 0.015 ℃/W,and the SRS suppression ratio is nearly 23 dB.展开更多
At first, we systematically sum up and deduce the figure of merit of the compensator using linearly chirped fiber gratings. Secondly, we solve the Reccatti differential equation by the Runge Kutta method and calcul...At first, we systematically sum up and deduce the figure of merit of the compensator using linearly chirped fiber gratings. Secondly, we solve the Reccatti differential equation by the Runge Kutta method and calculate the reflectivity and dispersion of the linearly chirped fiber gratings to obtain the figure of merit numericallu.On the other hand, we also discuss the figure of merit under the circumstances of three kinds of coupling coefficients and compare them Finally, we present one kind of perfect design of the compensator using the Gauss coupling function, and simply discuss the method to realize the Gauss coupling function in the fabrication of linearly chirped fiber gratings in this paper.展开更多
The analysis of the group delay ripple (GDR) generated by chirped fiber gratings is developed based on the Fabry-Perot (F-P) resonator. It shows clearly how the GDR is generated and why the periods of GDR varies along...The analysis of the group delay ripple (GDR) generated by chirped fiber gratings is developed based on the Fabry-Perot (F-P) resonator. It shows clearly how the GDR is generated and why the periods of GDR varies along the chirped fiber gratings. It could also explain why apodization could suppress the GDR and how apodization affects the chirp of the grating. The theory could be used to devise the apodization of fiber gratings.展开更多
文摘A chirped fibre Bragg grating according to ITU-T suggested L-band （2nd channel λ1 = 1570.83 nm; 80th channel λ2 = 1603.57 nm） with more than 1800 ps/nm single channel dispersion compensation is presented in this paper, of which the cladding mode loss, the delay curve ripple and the power fluctuation of the reflected spectrum are less than 0.5 dB, 50 ps and 0.25 dB, respectively. With this new FBG as dispersion compensation device, a 2 × 10 Gb/s wavelength division multiplexing （WDM） L-band transmission of 600 km based on conventional single mode fibre （G.652 fibre） is performed without forward error correction. The bit error rate （BER） is less than 10-12 and the power penalties of the 2nd and 80th channel of L-band are 1.8 dB and 2.0 dB, respectively.
文摘In this paper,we propose the novel system of multipoint measurement.The sensors of measurements are chirped Bragg grating and the interrogation of sensors is sub-carrier phase.The wavelength division multiplexing technique is used for addressing a network of FBG sensors and the time-division multiplexing technique is used for multipoint measurements.In the system,the modulation frequency of 200 MHz is adopted.The range of dectetion is from 0 to 900μεand the resolution is 12με. The time of the sensor response is about 1ns.
文摘Based on the general theory of linear Chirped Bragg fiber grating, this paper discusses some parameters including different chirped values and quasi gauss coupling function relating with the reflectivity coefficient dispersion compensation.The result shows that selecting larger chirped value and appropriate qusi guass coupling function can improve the dispersion compensation while ensuring high reflectivity. The concept of "figure of merit" in the microwave field is introduced to quantize the equalizing power of the dispersion compensator.
基金Project supported by the National Basic Research Program,China(Grant Nos.2010CB327605 and 2010CB328300)the National High-Technology Research and Development Program of China(Grant No.2013AA031501)+7 种基金the National Natural Science Foundation of China(Grant No.61307109)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120005120021)the Fundamental Research Funds for the Central Universities,China(Grant No.2013RC1202)the Program for New Century Excellent Talents in University,China(Grant No.NECT-11-0596)the Beijing Nova Program,China(Grant No.2011066)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications) Chinathe China Postdoctoral Science Foundation(Grant No.2012M511826)the Postdoctoral Science Foundation of Guangdong Province,China(Grant No.244331)
文摘We propose a novel lumped time-delay compensation scheme for all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. A linearly chirped fiber Bragg grating is optimally designed and used to compensate for the entire time-delays of the quantized pulses precisely. Simulation results show that the compensated coding pulses are well synchronized with a time difference less than 3.3 ps, which can support a maximum sampling rate of 151.52 GSa/s. The proposed scheme can efficiently reduce the structure complexity and cost of all-optical analog-to-digital conversion compared to the previous schemes with multiple optical time-delay lines.
基金the National Natural Science Foundation of China(Grant No.62105190)the Natural Science Foundation of Shanxi Province of China(Grant No.20210302124268)+1 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions of Shanxi Province of China(Grant No.2021L285)the Youth Researchof Shanxi University of Finance and Economics(Grant No.QN-202015)。
文摘Optical chaos has attracted widespread attention owing to its complex dynamic behaviors.However,the time delay signature(TDS)caused by the external cavity mode reduces the complexity of optical chaos.We propose and numerically demonstrate the critical dispersion of chirped fiber Bragg grating(CFBG)for eliminating the TDS of laser chaos in this work.The critical dispersion,as a function of relaxation frequency and bandwidth of the optical spectrum,is found through extensive dynamics simulations.It is shown that the TDS can be eliminated when the dispersion of CFBG is above this critical dispersion.In addition,the influence of dispersive feedback light and output light from a laser is investigated.These results provide important quantitative guidance for designing chaotic semiconductor lasers without TDS.
文摘Using the matrix approach,we analyzed the relation between the location of the transmission in stop band and the phase shift,and discussed the problem of varying the bandwidth of the transmission window.These theoretical results in this paper have important significance for actual application of the phase-shifted fiber grating.
基金the National Natural Science Foundation of China(No.10672065).
文摘2π phase ambiguity problem is very important in phase measurement when a deformed object has a large out of plane displacement. The dual-frequency projection grating phaseshifting profilometry （PSP） can be used to solve such an issue. In the measurement, two properchosen frequency gratings are utilized to synthesize an equivalent wavelength grating which ensures the computed phase in a principal phase range. Thus, the error caused by the phase unwrapping process with the conventional phase reconstruct algorithm can be eliminated. Finally, experimental result of a specimen with large plastic deformation is given to prove that the proposed method is effective to handle the phase discontinuity.
基金Project supported by the Paper Fund of Beijing Jiaotong University, China （Grant No 2005RC033） and the National Natural Science Foundation of China （Grant No 60477017）.
文摘Temperature and strain characteristics of uniform fibre grating with tapered metal coatings have been analysed theoretically, by which adjustable chirp characteristics of such gratings are shown. Electroplating is adopted to fabricate such gratings, and the tapered metal coating is obtained by gradually drawing the fibre grating out of the solution during the process of electroplating. The gradually changing cross-sectional area of the metal coating is calculated by a newly suggested numerical method. By combining the theoretical and numerical simulation analyses, the gratings＇ characteristics are given at various temperatures and strains. The results obtained using such a method are also testified by experiments.
文摘Chirped fibre Bragg gratings （CFBGs） are required to be concatenated to compensate the fibre dispersion in the dense wavelength-division multiplexing （DWDM） systems. When the channel spacing is small, the performance of CFBGs is degraded, which restricts the usage of fibre gratings. The origin of the interactions between the gratings is analysed and methods of suppressing the interactions are also proposed.
基金supported by the National Key Research and Development Program of China(No.2017YFB1104400)
文摘Suppression of stimulated Raman scattering(SRS)by means of chirped and tilted fiber Bragg gratings(CTFBGs)has become a key topic.However,research on high-power systems is still lacking due to two problems.Firstly,after the inscription,there are a large number of hydroxyl compounds and hydrogen molecules in CTFBGs that cause significant heating due to their strong infrared absorption.Secondly,CTFBGs can couple Stokes light from the core to the cladding and the coating,which causes serious heating in the coating of the CTFBG.Aimed at overcoming these bottlenecks,a process that combines constant-low-temperature and variable-high-temperature annealing is used to reduce the thermal slope of the CTFBG.Also,a segmented-corrosion cladding power stripping technology is used on the CTFBG to remove the Stokes light which is coupled to the cladding,which solves the problem of overheating in the coating of the CTFBG.Thereby,a CTFBG with both a kilowatt-level power-carrying load and the ability to suppress SRS in a fiber laser has been developed.Further,we establish a kW-level CW oscillator to test the CTFBG.Experimental results demonstrate that the power-carrying load of the CTFBG is close to 1 kW,the thermal slope is lower than 0.015 ℃/W,and the SRS suppression ratio is nearly 23 dB.
文摘At first, we systematically sum up and deduce the figure of merit of the compensator using linearly chirped fiber gratings. Secondly, we solve the Reccatti differential equation by the Runge Kutta method and calculate the reflectivity and dispersion of the linearly chirped fiber gratings to obtain the figure of merit numericallu.On the other hand, we also discuss the figure of merit under the circumstances of three kinds of coupling coefficients and compare them Finally, we present one kind of perfect design of the compensator using the Gauss coupling function, and simply discuss the method to realize the Gauss coupling function in the fabrication of linearly chirped fiber gratings in this paper.
基金This work was supported by the National 863 Plan(2001AA120201)
文摘The analysis of the group delay ripple (GDR) generated by chirped fiber gratings is developed based on the Fabry-Perot (F-P) resonator. It shows clearly how the GDR is generated and why the periods of GDR varies along the chirped fiber gratings. It could also explain why apodization could suppress the GDR and how apodization affects the chirp of the grating. The theory could be used to devise the apodization of fiber gratings.
