关键词: 全光纤干涉仪/
有效折射率/
包层模/
频谱
English Abstract
Simulation and analysis of sensing modes of in-fiber interferometer
Li Li-Jun1,2,3,Ma Qian2,
Cao Mao-Yong2,3,
Gong Shun-Shun1,
Li Wen-Xian1,
Guo Xiao-Li1,
Liu Yi-Lin1,
Xu Lin1,
Liu Qian1
1.College of Electronics, Communication and Physics, Shandong University of Science and Technology, Qingdao 266590, China;
2.College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, China;
3.State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
Fund Project:Project supported by the Shandong Provincial Natural Science Foundation of China (Grant Nos. ZR2009AM017, No.ZR2013FM019), the National Postdoctoral Project of China (Grant Nos. 200902574, 20080441150), Shandong Provincial Education Department Foundation of China (Grant No. J06P14), Qingdao Development Zone Project, China (Grant No. 02030093101) and Opening Foundation of State Key Laboratory of Minning Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, China (Grant No. MDPC201602).Received Date:10 May 2017
Accepted Date:04 August 2017
Published Online:05 November 2017
Abstract:The cladding mode of the in-fiber interference sensor relates to the externally sensing physical quantity, so the investigation of the cladding mode is very important for designing and improving the sensing performance of the sensor. By using the finite difference beam propagation method, the interference spectra of the sensors with different lengths and different core-to-core diameter ratios are simulated. Its spatial frequency spectrum is obtained through Fourier transform. The effective refractive index of the dominant cladding mode can be obtained through analyzing its spatial frequency spectrum. Its corresponding cladding mode order can be determined through substituting the values of the effective refractive index into the dispersion equation of sensing optical fiber. The simulation results show that the number and the order of the cladding modes both increase with sensing part fiber length increasing. The interference spectrum becomes dense according to the superposition of multi order cladding mode interferences. Its free spectral space of the sensor output interference spectrum becomes small. With the variations of the input fiber and sensing fiber core-to-core diameter ratio, the power distributions among the modes change obviously. The increase of core-to-core diameter ratio can increase the number and order of the cladding modes.
Keywords: all in-fiber interferometer/
effective refractive index/
cladding modes/
spatial frequency spectrum
