Microwave photonic image rejection mixer based on a DP-QPSK modulator

A simple image rejection mixer based on a dual-polarization quadrature phase shift keying modulator is presented without a 90 degrees hybrid coupler in electrical field. By properly adjusting DC bias points in the integrated modulator and performing balanced photo-detection, the influence of image components can be well rejected. The simulation results show that a 52.24 dB image suppression ratio (ISR) and a conversion efficiency (CE) of -9.17 dB can be achieved by the proposed mixer. Besides, another research on the ISR and CE against non-ideal parameters is carried out. According to the simulation results, it can be figured that the main factor to influence the ISR and CE is the DC drifting which results both of them changed rapidly as the DC bias points deviate from the settled values. On the other hand, with different extinction ratios and LO signal powers and RF signal powers, the mixer still performs good ISR and CE.