Angular selectivity of SOI photodiode with surface plasmon antenna

Abstract

A novel angle selective photodetector with gold surface plasmon (SP) antenna on a silicon-on-insulator (SOI) photodiode (PD) is proposed to capture the direction of the incident light. Two types of SP antenna, namely one-dimensional line-and-space grating and two-dimensional hole array grating, are reported. The SP antenna efficiently couples the incident light with the waveguide modes in the SOI PD at specific incident angles. The analytical modelling based on the phase matching between the diffracted light from the SP antenna and the propagating light in the SOI predicts the angle selective behavior of the device. The simulation by finite difference time domain (FDTD) method and measurement have successfully confirmed the prediction. These characteristics to detect the light at different incident angles could be useful in emerging applications such as lensless imaging.