A Study on DBR Lasers and Related Demodulation Technologies

By their nature, traditional electronic sensors are unsuitable for use in harsh sensing conditions due mainly to their intrinsic properties of active electrification and poor Electromagnetic Compatibility (EMC), while the Distributed Bragg Reflector (DBR) laser based Fiber Bragg Grating (FBG) sensor systems are currently widely implemented as a popular alternative in terms of high speed, robustness and diversity of target sensing parameters. Fast and accurate demodulation of the spectral center wavelength of a fiber grating sensor is the key to realizing a high-precision FBG sensor system. In this paper, the wavelength drift characteristics of narrow band DBR lasers are studied, and the corresponding wavelength drift correction techniques to improve the FBG wavelength demodulation accuracy (by 79%, from 75.8 pm to 15.9 pm) by the introduction of a temperature-controlled FBG reference optical path are investigated. In addition, a comparative study of various FBG peak-seeking algorithms is conducted to control the wavelength drift within 1.2 pm, which has improved the demodulation stability of the FBG sensor system.