Phase interrogation birefringent-refraction sensor for refractive index variation measurements

A birefringent-refraction (BR) sensor for measuring refractive indices of liquid solutions based on phase interrogation in a heterodyne interferometer is proposed. We theoretically investigate a comprehensive performance comparison between a surface plasmon resonance (SPR) sensor and the proposed BR sensor in terms of sensitivity and the dynamic range in refractive index measurements. In comparison with a typical SPR sensor, the simulations and experiments show that BR sensors can achieve the same order of sensitivity but with a flexible incident angle and a wide RI range.