Distortion Comparison of Single-Sideband Coherent Analog Optical Links Employing X-Cut and Z-Cut Mach–Zehnder Modulators

A single-sideband coherent analog optical link is implemented using a null-biased Mach-Zehnder (MZ) intensity modulator followed by a narrowband optical bandpass filter. The fidelity performance of such a link is compared between cases with X-cut and Z-cut MZ LiNbO3modulators. It is shown that for the case of Z-cut modulators, the converted radio-frequency output contains higher nonlinear distortions. Under the same operating condition, the spurious-free dynamic range of an X-cut link outperforms that of a Z-cut link by 2.6 dB.