The improvement of the signal to noise ratio （SNR） has significant meaning to the fiber Bragg grating （FBG） sensing system. The source of the noise as well as the signal attenuation of the FBG sensing system is an...The improvement of the signal to noise ratio （SNR） has significant meaning to the fiber Bragg grating （FBG） sensing system. The source of the noise as well as the signal attenuation of the FBG sensing system is analyzed. It is found that optical noise caused by the optical return loss （ORL） is the main source of noises in the system, and the coupler is the main source of attenuation of the signal. The cause of the ORL in fiber-optic elements （such as jumper cables connector and fiber end） is presented. In addition, suggestions to optimize the fiber optical sensing network in order to improve the SNR are presented. Methods to suppress noises caused by the fiber end interfaces of FBGs, including using index-matching fluid, bending fiber p!gtails in the way mentioned in this paper and cleaving the slant angle of the fiber interfaces to be 8, all contribute to the optimized SNR. Besides, the thermo-weld method is suggested to be used for both parallel and serial FBG setups to provide a low insertion loss. The results would be a useful engineering tool to design the high SNR optical sensing system.展开更多
A sensor array system formed by arranging four asymmetric distributed-feedback fiber lasers （DFB-FL） in ascending order according to their slope efficiencies was proposed. The output flatness could be effectively im...A sensor array system formed by arranging four asymmetric distributed-feedback fiber lasers （DFB-FL） in ascending order according to their slope efficiencies was proposed. The output flatness could be effectively improved with the application of asymmetric DFB-FLs. The last element had almost the same output with the others although it obtained the smallest pump power. The relative intensity noise （RIN） and relaxation oscillation frequency of the sensor array were also analyzed. It is found that the relaxation oscillation frequency of a certain DFB-FL was relevant to its relative position in the array. And the RIN of a certain DFB-FL was always affected by the other elements in the array, which was not dependent on the order of their arrangement.展开更多
The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algori...The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algorithm to realize probe wave power normalization for eliminating this impact was proposed. The principle of the proposed method was described theoretically. And the contrast test between our new method and conventional one was carried out. The experiment results indicated that the temperature accuracy was effectively improved from ＋5 C to 2 C.展开更多
文摘The improvement of the signal to noise ratio （SNR） has significant meaning to the fiber Bragg grating （FBG） sensing system. The source of the noise as well as the signal attenuation of the FBG sensing system is analyzed. It is found that optical noise caused by the optical return loss （ORL） is the main source of noises in the system, and the coupler is the main source of attenuation of the signal. The cause of the ORL in fiber-optic elements （such as jumper cables connector and fiber end） is presented. In addition, suggestions to optimize the fiber optical sensing network in order to improve the SNR are presented. Methods to suppress noises caused by the fiber end interfaces of FBGs, including using index-matching fluid, bending fiber p!gtails in the way mentioned in this paper and cleaving the slant angle of the fiber interfaces to be 8, all contribute to the optimized SNR. Besides, the thermo-weld method is suggested to be used for both parallel and serial FBG setups to provide a low insertion loss. The results would be a useful engineering tool to design the high SNR optical sensing system.
文摘A sensor array system formed by arranging four asymmetric distributed-feedback fiber lasers （DFB-FL） in ascending order according to their slope efficiencies was proposed. The output flatness could be effectively improved with the application of asymmetric DFB-FLs. The last element had almost the same output with the others although it obtained the smallest pump power. The relative intensity noise （RIN） and relaxation oscillation frequency of the sensor array were also analyzed. It is found that the relaxation oscillation frequency of a certain DFB-FL was relevant to its relative position in the array. And the RIN of a certain DFB-FL was always affected by the other elements in the array, which was not dependent on the order of their arrangement.
文摘The impact of microwave sweeper power fluctuation in the BOTDA system has been theoretically analyzed and experimentally tested. And a novel method comparing real-time acquisition of probe wave power with a new algorithm to realize probe wave power normalization for eliminating this impact was proposed. The principle of the proposed method was described theoretically. And the contrast test between our new method and conventional one was carried out. The experiment results indicated that the temperature accuracy was effectively improved from ＋5 C to 2 C.
