An optical channelized receiver (OCR) with a novel structure based on two coherent optical frequency combs (OFCs) and a Fabry-Perot (FP) filter has been proposed. Input wideband signals are multicasted in all optical channels by modulating one OFC. Then, different sub-frequency bands in all optical channels are filtered out by the FP filter. Finally, the sub-frequency bands are directly converted to intermediate frequency (IF) via coherent optical heterodyne with the LO provided by another OFC. Experiment results shows that the OCR works in X band with 8 channels, and the bandwidth of each channel is 500MHz, which means the instantaneous bandwidth of the OCR is 4GHz. The max power fluctuation between different channels is 4dB, which can be improved by adding proper attenuators to certain channels. The spurious free dynamic range (SFDR) of all channels is above 44dB under noise bandwidth of 1MHz, which equals to 84 dB·Hz<sup>2/3</sup>.
Broadband, free beam squinting and large scanning angle are essential for many applications. In views of these requirements, a tunable optical beam-forming for millimeter wave is proposed and demonstrated experimentally based on dispersive prism and variable optical delay line (VODL). Experiments are implemented with 1×4 antenna array operating at Ka band. Two beams are produced simultaneously for amplitude comparison direction finding. By tuning the relative delay of four VODLs, the beams can sweep across -30°~30°.
A wide-band microwave frequency shifter with high precision has been proposed and constructed based on paralleled PM and DP-MZM. PM is used to control the optical carrier phase that is driven by a sawtooth wave with a center frequency, while DP-MZM is used to generate a single-sideband suppressed carrier modulation. Results show that the frequency shift of kHz~GHz can be realized with the microwave carrier suppression of better than 50dB.