Broadband Microwave Signal Processing Based on Photonic Dispersive Delay Lines

The development of communications technologies has led to an ever-increasing demand for a higher speed and wider bandwidth of microwave signal processors. To overcome the inherent electronic speed limitations, photonic techniques have been developed for processing of ultrabroadband microwave signals. A dispersive delay line (DDL) is a key photonic device that can be used to implement signal processing functions, such as time reversal, time delay, dispersion compensation, Fourier transformation, and pulse compression. Compared with an electrical delay line, a photonic DDL has a much wider bandwidth and can be used for processing a microwave signal with a much wider bandwidth. In this paper, we review our recent work using photonic DDLs for processing of broadband microwave signals. Two types of DDLs are to be discussed, a linearly chirped fiber Bragg grating-based DDL and an optical dispersive loop-based DDL. Signal processing functions including microwave time reversal, microwave temporal convolution, time-stretched sampling, microwave waveform generation with an extended temporal duration, and wideband true-time delay beamforming are discussed.