Broadband photonic-assisted microwave receiver with high cross-channel interference suppression and image rejection.

A broadband photonic-assisted microwave receiver with high cross-channel interference suppression and image rejection is proposed and experimentally demonstrated. At the input of the microwave receiver, a microwave signal is injected into an optoelectronic oscillator (OEO), which functions as a local oscillator (LO) to generate a low-phase noise LO signal as well as a photonic-assisted mixer to down-convert the input microwave signal to the intermediate frequency (IF). A microwave photonic filter (MPF), realized by the joint operation of a phase modulator (PM) in the OEO and a Fabry-Perot laser diode (FPLD), is used as a narrowband filter to select the IF signal. Thanks to the wide bandwidth of the photonic-assisted mixer and the wide frequency tunable range of the OEO, the microwave receiver can support broadband operation. The high cross-channel interference suppression and image rejection are enabled by the narrowband MPF. The system is evaluated experimentally. A broadband operation from 11.27 to 20.85 GHz is demonstrated. For a multi-channel microwave signal with a channel spacing of 2 GHz, a cross-channel interference suppression ratio of 21.95 dB and an image rejection ratio of 21.51 dB are realized. The spurious-free dynamic range (SFDR) of the receiver is also measured to be 98.25 dB·Hz. The performance of the microwave receiver for multi-channel communications is also experimentally evaluated.