Modulators

Abstract

The modulation of optical fields is essential for communication applications. The output of injection semiconductor lasers can be modulated internally by modulating the injection current. This is the simplest modulation process for low frequency modulation applications. External modulation of the output of any laser type is most commonly done by electro-optic, acousto-optic or magneto-optic devices. We will not refer to these kinds of device in this chapter since their working principle and performances can be found in almost any textbook on optoelectronics. Instead, we focus here on advanced modulators based on the optical properties of mesoscopic structures, advanced bulk semiconductor modulators and on fiber modulator devices. Any one of them can produce either amplitude or phase modulation.