Transactions of Nanjing University of Aeronautics & Astronautics
Influence of Refractive Index Distribution on Brillouin Gain Spectrum in GeO2-Doped Optical Fibers
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Abstract:
GeO2 is commonly used as dopant to adjust the refractive index profile （RIP） and the acoustic velocity profile （AVP） in the fiber， thereby forming different Brillouin gain spectrum （BGS） characteristics such as Brillouin gain， acoustic mode number and peak intensity difference. When an optical fiber is used in optical fiber sensing or communication system， its BGS characteristics may play an important role in determining the performance of the system. In this paper， finite element analysis（FEA） method is used to study the influence of refractive index distribution and its corresponding AVP on the BGS in step-index， graded-index， and complex-index optical fibers. A new method has also been proposed to efficiently discriminate acoustic mode solution and obtain the new and full images of total Brillouin gain and acoustic modes number of the fiber as a function of the refractive index distribution， considering the influence of changing the refractive index difference and the geometric size simultaneously. For each type of optical fiber， the recommended parameter range is provided for optical fiber sensing and optical fiber communication. Moreover， the suitable optical fiber with close peak intensity in its multi-peak BGS is explored and achieved， which can be used in Brillouin beat spectrum detection systems to improve sensing accuracy.
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Project Supported:
This work was supported by the National Natural Science Foundation of China （Nos.61875086，61377086）， the Aerospace Science Foundation of China （No.2016ZD52042） and the Foundation of Graduate Innovation Center in Nanjing University of Aeronautics and Astronautics （No. kfjj20170801）.
Clc Number:
O437.2
CHINA AERO-SCIENCES
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