Photonic Image-free Mixer Based on a Dual-Parallel Mach-Zehnder Modulator and Fiber Dispersion for Radio-Over-Fiber System

In this paper, a simple image rejection mixer based on the dispersion effect in the single mode fiber is proposed and experimentally demonstrated for the radio-over-fiber (RoF) system. The key idea is to control the DC bias voltages of the dual parallel Mach-Zehnder modulator (DPMZM) to compensate for the desired components and eliminate the image induced components simultaneously during the fiber transmission. The experimental results show, the image rejection ratio (IRR) of ~50 dB is realized, and the spurious free dynamic range (SFDR) is about 100.75 dB·Hz
^2/3
. In addition, the results also demonstrate an image-free intermediate frequency (IF) range of 0.5 GHz-9.5 GHz. This image-free mixer can be widely employed in the radio-over-fiber (RoF) system, and greatly simplify the receiver structure in the base station.