Digital Linearization and Full Spectrum Utilization for Phase-Modulation Photonic Downconversion

Based on phase modulator, balanced photodetector, and fiber Bragg grating, we present a novel microwave downconversion method using direct-detection and post digital signal processing (DSP) to improve the gain and dynamic range of the link theoretically and experimentally. Both the reflection and transmission spectrum are used to increase the system gain. Experimental results show that this method increased the gain by 6 dB. In addition, the linearity of the system is improved by a simple strategy in the DSP module. This suppresses the third-order intermodulation by without sacrificing system gain. The experimental results show that the third-order limited spurious-free dynamic range increases by 5 dB.