Design of an angle detector for laser beams based on grating coupling

Abstract

A novel angle detector for laser beams is designed in this paper. It takes advantage of grating coupling to couple the incident light into a slab waveguide; and, the incident light's angle can be determined by reading the outputs of light detectors within the waveguide. This device offers fast-responding on-chip detection of laser beam's angle. Compared to techniques based on quadrant photodiodes or lateral effect photodiodes, the device in this paper has far greater detectable range (up to a few degrees, to be specific). Performance of the laser angle detector in this paper is demonstrated by finite-differencetime-domain simulations. Numerical results show that, the detectable angle range can be adjusted by several design parameters and can reach [-4o, 4o]. The laser beam angle detector in this paper is expected to find various applications such as ultra-fast optical interconnects. © 2012 by the authors.