Wideband photonic microwave channelization and image-reject down-conversion

A wideband photonic microwave channelization and image-reject down-conversion system is proposed and experimentally demonstrated. The broadband radio frequency (RF) and electrical local oscillator (LO) signals are applied to Mach–Zehnder modulators (MZMs) and be multiplexed for channelized reference. By employing DPMZMs, different optical frequency shifting LO signals for channelization are generated. Due to the frequency difference between the modulated RF signals and frequency shifted LO signals, multichannel intermediate frequency (IF) signals can be easily separated by the followed photonic I/Q receiver. Experimental results show that the RF signal with a bandwidth of 3 GHz could be down-converted into six IF signals with the same center frequency of 750 MHz and the same bandwidth of 500 MHz. The measured spurious free dynamic range (SFDR) is 101 dB•Hz ^2∕3 , the passband fluctuation is less than 0.5 dB; the channel isolation is over 22 dB, and the image-rejection is over 22 dB. A QPSK vector signals with 50 Msym/s and 16.5–19.5 GHz operating frequency is successfully demonstrated using the proposed scheme, and good EVMs and constellation diagrams are obtained. The proposed photonic channelization and image-reject down-conversion system may have potential applications in the RF frontends of future systems such as broadband integrated satellite communication and multi-service wireless networks.