Phase-detection-sensitivity enhancement of grating-coupled surface plasmon resonance sensor with light incident at nonzero azimuth angle

We have numerically and experimentally demonstrated the enhancement of phase detection sensitivity of a grating-coupled surface plasmon resonance (GCSPR) sensor by using incident light at a nonzero azimuth angle. Phase detection measurements were performed using an electro-optic heterodyne interferometer. When the GCSPR sensor was rotated azimuthally by 0 deg and 58 deg, the phase detection sensitivities were approximately 3.2 × 10 ^-7 RIU and 5.5 × 10^-8 RIU, respectively. The azimuth angle of 58deg was found to enhance the sensor sensitivity by a factor of 5.87 relative to the azimuth angle of 0 deg.