Demonstration of a wide-band image rejection microwave downconverter

A photonic image-rejection downconverter capable of down-converting radio-frequency (RF) signals over a range of 5-18 GHz into an IF band 2.1 GHz wide (3.3-5.4 GHz) is presented. RF signals received by the system are first up-converted into the passband of a 21.3-23.4-GHz filter, and then optically down-converted to 3.3-5.4 GHz. The system exhibited better than 60 dB of image rejection over its entire bandwidth and spurious signals resulting from harmonic mixing products were more than 25 dB below the downconverted signal.