Microwave photonics‐based channelized receiving and reconstruction for broadband RF signal

Abstract

A microwave photonics-based channelized receiver for broadband vector signals is proposed and experimentally demonstrated. A 4-line optical frequency comb (OFC) generated by a dual-parallel Mach-Zehnder modulator (DPMZM) is used as local oscillator (LO) signal in the in-phase/quadrature (I/Q) receiver for coherently down-converting the broadband signal into different channelized bands. By properly setting the frequency difference between the OFC comb line and the broadband signal, either homodyne or heterodyne detection of I/Q receiver is realized. To compensate the amplitude difference and phase difference of adjacent channel signals, an overlap ratio of adjacent slices is introduced for channel equalization and signal reconstruction. The simulated result shows the error vector magnitude of 4-channel channelization for a reconstructed 8 GBaud quadrature phase shift keying (QPSK) signal is very close to the original one. In the experiment, 2-channel channelization for a 2 GBaud QPSK is realized and the whole signal is reconstructed successfully. The experimental result also proves the quality improvement of reconstructed signal with an increase of channel overlap ratio.