Suppression of third-order intermodulation distortion in analog photonic link based on an integrated polarization division multiplexing Mach–Zehnder modulator

A simple and linear analog photonic link (APL) based on a single integrated polarization division multiplexing Mach–Zehnder modulator (PDM-MZM) is proposed with suppressed third-order intermodulation distortion (IMD3). By properly selecting the modulation indexes of radio frequency (RF) signals and bias angles in the two sub-modulators, the electric/optical power ratio is changed and thus two nonlinear distortion signals with opposite phases are constructed to cancel out IMD3 of the link. Therefore, the IMD3 can be suppressed and the spurious-free dynamic range (SFDR) of the system can be improved. Only one electrode in each sub-modulator is used in the experiment. Experimental results show that compared with the conventional link based on a single MZM, 33.7-dB reduction of IMD3 is achieved and an enhancement of 17.6 dB in SFDR can be obtained. Besides, the proposed APL is test by a 16 quadrature amplitude modulation (QAM) RF signal and the error vector magnitude (EVM) and adjacent channel power ratio (ACPR) of the link are measured.