Frequency modulation on single sideband using controlled dynamics of an optically injected semiconductor laser

Nonlinear dynamics of an optically injected semiconductor laser is applied to photonic microwave generation. By properly adjusting the injection conditions, the optical frequency of the slave laser is first locked to the master laser. The slave laser is then driven into a periodic dynamical state, resulting in a single-sideband (SSB) microwave modulation on the optical carrier. The frequency of the SSB can be controlled by the optical injection strength and detuning. Frequency-modulated SSB can, thus, be obtained from a modulated injection. In this work, we experimentally investigate the generated SSB in terms of its broad tunability and fast modulation response. The results suggest application of this system in radio-over-fiber and optical subcarrier multiplexing technologies when microwave frequency modulation or frequency-shift keying is employed.

I. Introduction

Optically injected semiconductor lasers have recently been used in photonic microwave generation [1]. In a master–slave configuration with a sufficient injection power, the optical frequency of the slave laser is injection locked to that of the master laser. By properly adjusting the injection strength and the frequency detuning, instability occurs through Hopf bifurcation into the period-one dynamical state. The result is a tunable microwave oscillation in the optical power of the slave laser [2]. This method of photonic microwave generation offers many advantages due to its single-sideband (SSB) spectrum, broad-frequency tuning range, and ease of stabilization.