Suppression of second-order harmonic distortion in ROF links utilizing dual-output MZM and balanced detection

We demonstrate a novel approach to eliminate the second-order harmonic distortions (SHD) in radio over fiber (ROF) links utilizing a dual-output Mach-Zehnder modulator and balanced detection. Experimental results are presented for a 5GHz link exhibiting a 35.8dB suppression of the SHD and 5.89dB enhancement of the fundamental power, resulting in a significant improvement of 18dB in the second-order spurious-free dynamic range (SFDR). The error vector magnitude (EVM) performance of the demodulated 16 quadrature amplitude modulation (QAM) signal is effectively improved to be 5.01% when the 16 QAM signal centered at 10GHz together with another signal centered at 5GHz are distributed through the link, simultaneously. Experimental results clearly show that multi-octave operation can be achieved in multi-channel ROF link using the proposed scheme. The link shows excellent potential for low cost ROF links as the simplicity of the system is preserved.