Photonic Downconversion and Linearization of Microwave Signals from the X - to $K\!$ -Band

A linearized photonic radio frequency (RF)-to-intermediate frequency (IF) conversion system is proposed and experimentally demonstrated based on balanced detection and digital signal postcompensation. The optical carrier suppression and remodulation scheme is employed to significantly reduce the local oscillator frequency requirements and common mode optical phase noises. Photonic IF downconversion is enabled by using a reconfigurable multiport optical processor and balanced coherent detection of the spectrally separated lower and upper first-order sidebands of the phase modulated signals. Moreover, the digital linearization technique is used to suppress the third-order intermodulation components by more than 21 dB and an improvement of the spurious free dynamic range as large as 7 dB for RF signals ranging from 8-20 GHz is also achieved.