Highly Birefringent Microfiber Hybrid Interferometer Sensor

In this work, an optical microfiber-based hybrid interferometer is presented. A combination of two types of in-line interferometers is achieved by inserting a section of nonadiabatic tapered polarization maintaining microfiber into a Lyot filter. The hybrid interference spectrum shown as large spectrum envelope and fine fringes, corresponding to the polarized and modal interferences is obtained. We experimentally investigate the response characteristics of the two-interference system using both spectral interrogation and spatial frequency domain analysis. The refractive index sensitivities are 1150.0nm/RIU and 1779.8nm/RIU, and the temperature sensitivities are 190pm/°C and -12.7 pm/°C for two interferences, respectively. The proposed hybrid interferometer has the advantages of simple device and compact structure, and has the potential of simultaneous measurement of multiple parameters.