Double Phase Matching in MZI With Antiresonant Effect for Optical Fiber Sensor Application

In the traditional Mach-Zehnder interferometer, only one phase matching condition needs to be satisfied for destructive interference. Here, we propose and demonstrate a Mach-Zehnder interferometer with double phase matching condition, which satisfies both the destructive condition of double beam interference and the resonant condition of anti-resonant effect. Different from the traditional method, the interference is construed as a coherent superposition between anti-resonant beam and cladding one. The effect of the multimode fiber length on the energy distribution and transmission spectrum is analyzed precisely. The experimental results show that the intensity of the wavelength meeting double phase matching condition is extremely sensitive to both strain and temperature. The maximum intensity sensitivity to strain and temperature are up to 16.1 dB/mε and 0.181 dB/°C, respectively. Compared with the previous work, the sensitivities have been improved several times or even tens of times. The proposed Mach-Zehnder interferometer with double phase matching condition can improve the dip depth, which has a great potential value in sensing application.