Variable-chirped microwave waveform generator based on reconfigurable microwave photonic filter

Abstract

An optical approach to generating chirped microwave signal using a photonic microwave delay-line filter (PMDLF) with a quadratic phase response is proposed and demonstrated. In this scheme, a narrow band Gaussian pulse is used as the original signal. In order to eliminate the need for a wideband original microwave chirped-free signal, a mixer and a radio frequency signal are used to up-convert the spectrum of the original signal and the dispersion curve is tuned to minimize the attenuation caused by the fiber dispersion. Then the required frequency response can be reconstructed by a nonuniformly spaced PMDLF. Since the majority of the power of the original signal can bypass the filter, the power of the generated chirped microwave signal will be increased. A reconstruction example of a desired frequency response with a central frequency of 10 GHz is provided, and the generation of the corresponding chirped microwave signal is demonstrated by numerical simulations.