On-chip silicon optical phased array for two-dimensional beam steering

A 16-element optical phased array integrated on chip is presented for achieving two-dimensional (2D) optical beam steering. The device is fabricated on the silicon-on-insulator platform with a 250 nm silicon device layer. Steering is achieved via a combination of wavelength tuning and thermo-optic phase shifting with a switching power of P-pi = 20 mW per channel. Using a silicon waveguide grating with a polycrystalline silicon overlay enables narrow far field beam widths while mitigating the precise etching needed for conventional shallow etch gratings. Using this system, 2D steering across a 20 degrees x 15 degrees field of view is achieved with a sidelobe level better than 10 dB and with beam widths of 1.2 degrees x 0.5 degrees. (C) 2014 Optical Society of America