Harmonic and Intermodulation Performance of Quantum-Well Mach-Zehnder Electro-Optic Modulators with Electrical Biasing

Abstract

A mathematical model for the transfer function of the Mach-Zehnder interferometers based on the quantum-confined Stark effect (QCSE) is presented. The model, basically a cosine-series function, can easily yield closed-form expressions for the amplitudes of the harmonic and intermodulation components of the output when the input is formed of any scenario of large-amplitude multisinusoidal voltages. The special case of three-tone equal-amplitude input voltage is considered in detail. The results show the strong dependence of the harmonic and intermodulation performance on the electrical biasing. The results also show that for a proper selection of the electrical biasing the third-order intermodulation or the second-order intermodulation can be minimized. While the results obtained are in excellent agreement with previously published results, the present analysis is applicable to multisinusoidal input voltages with different scenarios and is not restricted to small-amplitude two-tone inputs only.