Sensors, Vol. 20, Pages 6071: Random Fiber Grating Characterization Based on OFDR and Transfer Matrix Method

Sensors, Vol. 20, Pages 6071: Random Fiber Grating Characterization Based on OFDR and Transfer Matrix Method
Sensors doi: 10.3390/s20216071
Authors:
Zichao Zhou
Chen Chen
Ping Lu
Stephen Mihailov
Liang Chen
Xiaoyi Bao

Random fiber gratings (RFGs) have shown great potential applications in fiber sensing and random fiber lasers. However, a quantitative relationship between the degree of randomness of the RFG and its spectral response has never been analyzed. In this paper, two RFGs with different degrees of randomness are first characterized experimentally by optical frequency domain reflectometry (OFDR). Experimental results show that the high degree of randomness leads to low backscattering strength of the grating and strong strength fluctuations in the spatial domain. The local spectral response of the grating exhibits multiple peaks and a large peak wavelength variation range when its degree of randomness is high. The linewidth of its fine spectrum structures shows scaling behavior with the grating length. In order to find a quantitative relationship between the degree of randomness and spectrum property of RFG, entropy was introduced to describe the degree of randomness induced by period variation of the sub-grating. Simulation results showed that the average reflectivity of the RFG in dB scale decreased linearly with increased sub-grating entropy, when the measured wavelength range was smaller than the peak wavelength variation range of the sub-grating. ...

Source: Sensors - October 26, 2020 Category: Biotechnology Authors: Zichao Zhou Chen Chen Ping Lu Stephen Mihailov Liang Chen Xiaoyi Bao Tags: Article Source Type: research