An Ultra-Wideband Microwave Photonic Channelizer Based on Coherent Optical Frequency Combs and Image-Reject Down-Conversion

Radio frequency (RF) channelization receiver is one of the most effective methods for processing ultra-wideband RF signals. In this paper, an ultra-wideband microwave photonic channelizer based on coherent optical frequency combs (OFCs) and image-reject down-converter is proposed and demonstrated. The OFCs used in the system are generated by two dual parallel Mach-Zehnder modulators (DPMZM), and the free spectrum range (FSR) is flexibly adjustable. The image-reject down-converter can not only effectively achieve image separation but also suppress the seven-order distortion and DC offset using balanced detection. A K- and Ka-band RF signal covering the frequency band from 25 to 30 GHz is sliced into 5 sub-channels with 1-GHz bandwidth, two-tone signals with frequencies of 27.5 and 27.51GHz are used to measure the spurious free dynamic range (SFDR) which is 116.8 dB$\cdot $ Hz
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, the image-rejection is over 66.4 dB, and the error vector magnitude (EVM) is 4.2%.