Proposal and experimental verification of Bragg wavelength distribution measurement within a long-length FBG by synthesis of optical coherence function

Abstract

In this paper, a sensor system for measuring continuous Bragg wavelength distribution in a long-length fiber Bragg grating is newly proposed, using synthesis of optical coherence function (SOCF), which is one of the spatial resolving techniques used for reflectometry. Experimental results are also reported. In the process of synthesizing optical coherence function, it is found that an apodization scheme is necessary to obtain the reflection spectrum of local section in a long-length FBG around the coherence peak. As a verification of this method, the detection of local Bragg wavelength shift due to temperature change within a short section in a long-length FBG is demonstrated experimentally.