Silicon-Based Optical Phased Array Using Electro-Optic p-i-n Phase Shifters

We present a 1 x 16 silicon optical phased array using electro-optic phase shifters to attain high-speed operation with low power consumption. The phase shifters are constructed using a p-i-n junction structure with the p- and n-doped regions formed on both sides of the i-region. The i-region width of the phase shifter is optimized considering the power consumption for phase-tuning and the propagation loss in the phase shifter. The fabricated p-i-n phase shifter exhibits a fast operating speed of 20 MHz and a low phase-tuning power of 1.7 mW/pi. From a 1-D optical phased array integrated with 2-mu m-pitch grating radiators, a wide beam-steering range of 45 degrees is attained along the transversal direction at a 1.55 mu m wavelength. Average power consumption for the beam-forming operation of the 1 x 16 OPA is measured to be 39.6 mW and the average transition time to steer the beam is 24 ns.