SFDR and gain enhancement in photonic downconversion link by linearization and full spectrum utilization

In this work, an all-optical scheme to improve the gain and linearity of the downconverted analog photonic link is proposed and verified. We utilize the different electro-optic coefficients of the z-cut LiNbO3 phase modulator to realize the suppression of the third-order intermodulation distortion. On this basis, the link gain is improved by reusing optical carrier and lower sidebands. The simulation results show that the spurious-free dynamic range is improved by ∼7.4  dB. And the link gain is increased by ∼13.42  dB compared to the linearized downconversion link without full spectrum utilization. This photonic downconversion has good feasibility and robustness in inaccurate polarized angle and phase mismatch situations. It can be realized in a wide frequency range and has a stable conversion gain on the condition of RF power changing.