An integrated optical beamforming network for two-dimensional phased array radar

Abstract

In recent years, optically controlled phased array radar has been widely used because of its high radiation power, flexible beam steering and anti-electromagnetic interference, but the radar system based on discrete devices is still plagued by the problems of large size, high power consumption and complex control method. In this paper, we propose a two-dimensional integrated optical true time delay network (OTTDN), which has the abilities of real-time monitoring and adjustment. The delay network is implemented with silicon-based adjustable optical delay chip. The chip contains four-channel delay lines with different steps to achieve more compact volume, which can realize 128 × 4 kinds of delay amount, but the size is only 5.7 × 15.8 mm2 and the power consumption of all chip is 4.32 W. The results of delay chip measurement show that the maximum delay mean error is -0.55 ps, and the maximum root mean square error (RMSE) is 0.80 ps in four-channel. Based on these delay results, the pointing error of array antenna is less than 0.5° in the frequency of 3 GHz. If a power division structure is added to the RF front-end, this network can also be used in multi-beam systems, whose beams can be controlled independently at the same time.