RF Performance of Single Sideband Modulation Versus Dual Sideband Modulation in a Photonic Link

Abstract

Single sideband optical modulation can be used in multiple RF photonic link applications. However, single sideband optical modulation is often thought to provide lower RF output power than traditional dual sideband modulation techniques. While true in one specific case, it is not true in all cases. We theoretically and experimentally analyze the RF performance of a photonic link utilizing a Z-cut dual-electrode Mach-Zehnder intensity modulator with a 90° RF hybrid that produces optical single sideband modulation. The single sideband performance is compared to double sideband modulation using the same Mach-Zehnder modulator in either a push-pull configuration using a 180° RF hybrid or a single-arm drive configuration. The optical sideband powers, RF output power and the output intercept power and spur-free dynamic range of the third-order intermodulation nonlinearity are compared both theoretically and experimentally for each of the three cases. The performance of a double sideband modulated link using an X-cut inherently push-pull Mach-Zehnder modulator is also compared theoretically, assuming the same Vπ and insertion loss as the dual-electrode Mach-Zehnder modulator.