Highly sensitive optical length measurement by using a microwave photonic filter with multi-passband

摘要

In this paper, a method for optical length measurement that employs a multi-passband microwave photonic filter (MPF) is analysed and demonstrated experimentally. The MPF consists of a sliced broadband light source, a phase modulator, a dual-parallel dispersion medium and a photodetector (PD). By cascading two Mach-Zehnder interferometers (MZIs) with different arm length difference, the MPF with eight passbands has been obtained. The variation of the length difference of MZI will lead the change of the free spectral range (FSR) of the interference spectrum, as well as the frequency of the passbands. By changing the arm length of the MZI, a high length measuring sensitivity of -2.420 GHz/mm has been achieved. The MPF has broad application prospects in the field of multi-parameter sensing. Moreover, the sensor reveals the advantages of highly sensitive, easy to implement and is able to overcome the influence of the environmental perturbation, for example temperature.