A novel opening loop structure of fiber Bragg grating is proposed. From the analysis of the strain distribution at the side of the opening loop we found that the structure can be used as a new setup to linearly tune t...A novel opening loop structure of fiber Bragg grating is proposed. From the analysis of the strain distribution at the side of the opening loop we found that the structure can be used as a new setup to linearly tune the central wavelength of the fiber Bragg gating. The setup is an uniform fiber Bragg grating bonded to the side of a beam which can produce an uniform strain. The experimental results show that the wavelength range of linear tuning is about 5.0 nm,the sensitivity is about 3. ]8 nm/N and the linearity is up to 0. 9988.The largest tuning range of the setup is about 11. 0 nm while the linearity is 0. 9941 in the ranae of 0 and 11. 0 nm. ExPerimental results are in good agreement with our theoretical analysis.展开更多
A novel switchable dual-wavelength erbium-doped fiber(EDF)laser is demonstrated.The wavelength selection element consists of two fiber Bragg gratings(FBGs),a polarization controller(PC)and a 3 dB coupler forming a Sag...A novel switchable dual-wavelength erbium-doped fiber(EDF)laser is demonstrated.The wavelength selection element consists of two fiber Bragg gratings(FBGs),a polarization controller(PC)and a 3 dB coupler forming a Sagnac loop inserted with two FBGs.We study the effect of coupling ratio on filtering performance in this paper.By adjusting PC,we can change the wavelength-dependent loss,and then using nonlinear polarization rotation effect to suppress the mode competition caused by the homogeneous broadening of EDF,we obtain single-and double-wavelength laser outputs.At room temperature,under 200 mW pump power,dual-wavelength laser is achieved,and the center wavelengths are 1545.34 nm and 1548.20 nm,respectively.The peak power values are–13.36 dBm and–14.58 dBm,and side mode suppression ratios(SMSRs)are 41.10 dB and 39.88 dB,respectively.Within two hours,the maximum fluctuation of peak power is less than 0.7 dB,which shows that the demonstrated fiber laser is stable.Moreover,by adjusting PC,singel-wavelength laser output is obtained,the peak power is–6.27 dBm or–5.45 dBm,and SMSR is40.03 dB or 39.96 dB at 1545.34 nm or 1548.20 nm,respectively.展开更多
The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail...The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate (BER) of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio (SIR) and BER performance of the system are studied and simulated at the case with uneven distribution of chips' powers.展开更多
Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is...Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is proposed to improve MCF shape sensor accuracy using an ultraviolet transparent liquid mediated fiber Bragg grating(FBG)inscription technique and a twist-isolating packaging method.A newly developed UV index matching liquid(UV-IML)is used to generate uniform light field at all the MCF cores,enabling FBG inscription with high accuracy.Additionally,a new stress fully released(SFR)packaging method is implemented to isolate the sensor from any external twists.The MCF shape sensor shows a maximum relative error of only 3.33%and the lowest reported relative sensitivity error of 1.11%cm^(-1).Moreover,a real-time 3D shape sensing system with a response frequency larger than 30 Hz is constructed using the unique MCF shape sensor.The highly accurate real-time 3D shape sensing results indicate potential applications for in vivo shape estimation of endoscopies and soft robots.展开更多
An acoustic emission （AE） linear location system was proposed, which employed fiber Bragg gratings （FBGs） as AE sensors. It was demonstrated that the FBG wavelength could be modulated as the static case when the g...An acoustic emission （AE） linear location system was proposed, which employed fiber Bragg gratings （FBGs） as AE sensors. It was demonstrated that the FBG wavelength could be modulated as the static case when the grating length was much shorter than the AE wavelength. In addition, an improved AE location method based on the Gabor wavelet transform （WT） and threshold analysis was represented. The method was testified through AE linear location experiments based on a tunable narrow-band laser interrogation system using ultra-short FBG sensors as AE sensors. Results of the experiments showed that 86% of the linear location errors were less than 10mm.展开更多
A low cost, coolerless 980nm diode pumped, gain flattened L band EDFA with fast transient control, high pump efficiency and gain clamping effect was realized by using FBGs as C band seed generators.
基金Supported by the National 863 High Technology Project underGrant No.2002AA313110 ,the Science and Technology Innova-tion Foundation,the Students Innovation Foundation of NankaiUniversity,P.R.China .
文摘A novel opening loop structure of fiber Bragg grating is proposed. From the analysis of the strain distribution at the side of the opening loop we found that the structure can be used as a new setup to linearly tune the central wavelength of the fiber Bragg gating. The setup is an uniform fiber Bragg grating bonded to the side of a beam which can produce an uniform strain. The experimental results show that the wavelength range of linear tuning is about 5.0 nm,the sensitivity is about 3. ]8 nm/N and the linearity is up to 0. 9988.The largest tuning range of the setup is about 11. 0 nm while the linearity is 0. 9941 in the ranae of 0 and 11. 0 nm. ExPerimental results are in good agreement with our theoretical analysis.
基金supported by the National Natural Science Foundation of China(No.61107052)
文摘A novel switchable dual-wavelength erbium-doped fiber(EDF)laser is demonstrated.The wavelength selection element consists of two fiber Bragg gratings(FBGs),a polarization controller(PC)and a 3 dB coupler forming a Sagnac loop inserted with two FBGs.We study the effect of coupling ratio on filtering performance in this paper.By adjusting PC,we can change the wavelength-dependent loss,and then using nonlinear polarization rotation effect to suppress the mode competition caused by the homogeneous broadening of EDF,we obtain single-and double-wavelength laser outputs.At room temperature,under 200 mW pump power,dual-wavelength laser is achieved,and the center wavelengths are 1545.34 nm and 1548.20 nm,respectively.The peak power values are–13.36 dBm and–14.58 dBm,and side mode suppression ratios(SMSRs)are 41.10 dB and 39.88 dB,respectively.Within two hours,the maximum fluctuation of peak power is less than 0.7 dB,which shows that the demonstrated fiber laser is stable.Moreover,by adjusting PC,singel-wavelength laser output is obtained,the peak power is–6.27 dBm or–5.45 dBm,and SMSR is40.03 dB or 39.96 dB at 1545.34 nm or 1548.20 nm,respectively.
基金Supported by the Natural Science Research Foundation of Jiangsu Higher-Learning Insti-tution (No.04jkb510057).
文摘The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate (BER) of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio (SIR) and BER performance of the system are studied and simulated at the case with uneven distribution of chips' powers.
基金Major Scientific Research Project of Zhejiang Laboratory(No.2019MC0AD02)Innovation Project of Zhejiang Laboratory(No.2022MG0AL03)+1 种基金National Science Foundation of China(Nos.62204230,62020106002,T2293750,62205306,92250304)National Key Research and Development Program of China(2021YFC2401403)。
文摘Improving the accuracy of shape sensors based on multicore fibers(MCFs)is challenging but of great importance for real-time 3D shape detection,especially in visually inaccessible areas.In this work,a novel approach is proposed to improve MCF shape sensor accuracy using an ultraviolet transparent liquid mediated fiber Bragg grating(FBG)inscription technique and a twist-isolating packaging method.A newly developed UV index matching liquid(UV-IML)is used to generate uniform light field at all the MCF cores,enabling FBG inscription with high accuracy.Additionally,a new stress fully released(SFR)packaging method is implemented to isolate the sensor from any external twists.The MCF shape sensor shows a maximum relative error of only 3.33%and the lowest reported relative sensitivity error of 1.11%cm^(-1).Moreover,a real-time 3D shape sensing system with a response frequency larger than 30 Hz is constructed using the unique MCF shape sensor.The highly accurate real-time 3D shape sensing results indicate potential applications for in vivo shape estimation of endoscopies and soft robots.
基金The authors gratefully acknowledge the financial support for this work from the Natural Science Foundation of China （Grant No. 61074163） and the Natural Science Foundation of Shandong Province, China （Grant No. ZR2011FQ025）.
文摘An acoustic emission （AE） linear location system was proposed, which employed fiber Bragg gratings （FBGs） as AE sensors. It was demonstrated that the FBG wavelength could be modulated as the static case when the grating length was much shorter than the AE wavelength. In addition, an improved AE location method based on the Gabor wavelet transform （WT） and threshold analysis was represented. The method was testified through AE linear location experiments based on a tunable narrow-band laser interrogation system using ultra-short FBG sensors as AE sensors. Results of the experiments showed that 86% of the linear location errors were less than 10mm.
文摘A low cost, coolerless 980nm diode pumped, gain flattened L band EDFA with fast transient control, high pump efficiency and gain clamping effect was realized by using FBGs as C band seed generators.
