3 - Optical modulators

This chapter discusses the possible mechanisms for optical modulation, technology platforms, the current state of the art, and the prospects for the future progression of optical modulators, all for applications in data communication applications. Due to the ever-increasing demand for data, the transition from electrical to optical interconnect within data centers is inevitable. Due to their inclusion in more traditional optical communications applications, III–V material-based modulators were obvious candidates for short-reach interconnect, but the phenomenal rise of silicon photonics has meant that silicon-based modulators are now extensively deployed within such applications, and a brief review of the emergence of silicon-based modulators serves as a useful introduction to silicon photonics technology. Later in this chapter, we will see that recent alternatives are emerging, where other materials are introduced onto the silicon photonics platform as innovative ways of developing modulators that have the best attributes of the new materials but remain compatible with silicon photonics. This chapter begins with a discussion of modulation mechanisms, key modulator parameters, and figures of merit.