Fiber-optic surface plasmon resonance sensor based on spectral phase shift interferometric measurements

We demonstrate for the first time a fiber-optic surface plasmon resonance sensor employing the interrogation method based on spectral interferometric measurements of the phase shift between fiber polarization modes. The sensor was fabricated on a specially designed birefringent D-shape fiber made of silica glass, which exhibits modal birefringence of the order of 10−5 and allows for direct deposition of a metal layer in the vicinity of the core. The sensor characteristics measured using the spectral interferometry method were compared with the reference results obtained using the conventional spectral transmission method. The two measuring techniques show similar sensitivity of 2700 nm/RIU for the refractive index of external medium equal to 1.386, however, the detection accuracy of the interferometric method is up to 3 times better.