Highly Linear Radio-Over-Fiber System Incorporating a Single-Drive Dual-Parallel Mach–Zehnder Modulator

We propose a highly linear radio-over-fiber system with low intermodulation distortion (IMD) using a single-drive dual-parallel Mach-Zehnder modulator (SD-DPMZM). The optical carrier is modulated in one of the two parallel modulators, while remaining unmodulated in the other one. There exists optimal working points for SD-DPMZM that makes its two kinds of origins of third-order IMD (IMD3) have opposite phase and equal intensity, and cancel each other; hence the output IMD3 is suppressed dramatically. Experimental results show that the proposed scheme can achieve a spurious-free dynamic range of up to 122.9 dB · Hz^2/3, which is in agreement with the theoretical analysis. It is about 20 dB more than a conventional MZM. The error vector magnitude of the proposed scheme, for a 16-QAM 10-MSym/s signal centered at 4 GHz, is 1.94%.