Influence of light source on the strain sensitivity of a polarisation maintaining fibre loop mirror based on voltage demodulation

Abstract

The sensitivity is an important performance for a polarisation maintaining fibre (PMF) loop mirror (PM-FLM) sensor based on voltage demodulation. This paper investigates the method of improving the strain sensitivity of a PM-FLM based on voltage demodulation, including the demodulation principle, the derivation of the output light power equation, and experimentally studies on the strain sensitivity of a PM-FLM with different narrow-band input light source. The results show that the PM-FLM using a high-power light source as input has a high strain sensitivity but a small linear range of strain measurement, and the PM-FLM using a low-power light source as input has a low strain sensitivity but a large linear range of strain measurement. Hence, a high-power narrow-band light source as input can be chosen to improve the strain sensitivity, and the authors can also reduce the input light source power to enlarge the linear range of strain measurement.