Biasing Techniques for LiNbO₃ Mach–Zehnder Modulators with Emphasis on RFoF/AM, DSB-SC, and BPSK Modulation Schemes with Quad and Null Point Biasing

Abstract

Lithium niobate (LiNbO₃) Mach–Zehnder modulators (MZMs) are an important part of modern optical communication and microwave photonics systems due to their high linearity, wide bandwidth, and electro‑optic stability. A critical aspect governing the performance of an MZM is its biasing technique, which directly determines modulation efficiency, linearity, spectral purity, and noise performance. This paper gives a review and comparison of various biasing techniques for LiNbO3 MZMs with emphasis on radio-frequency- over-fiber / analog modulation (RFoF/AM), Double-Sideband Suppressed-carrier (DSB-SC), and Binary Phase-Shift Keying (BPSK) modulation schemes. The operating principles, different bias point selection for optimum operation, biasing requirements, comparative analysis and laboratory procedures for implementing the above-mentioned modulation schemes are discussed in detail.