Design principles of injection-locked semiconductor laser structures

Injection locking of semiconductor lasers has proven to be a versatile technique in a wide area of applications including Radio over Fiber (RoF) transmitters, optical comb generators, phase-arrayed antennas, mm-wave telescopes, etc. The injection-locked semiconductor laser acts as an optical amplifier, phase modulator, weak signal detector and optical filter. The stable locking and dynamic properties are strongly dependant on the cavity structure of these devices. A method based on semi-classical theory is presented for determining the effect of weak optical injection on the threshold gain and resonant frequency of complex-coupled DFB semiconductor lasers. This allows tailoring the locking bandwidth according to target application of the component and the establishment of design principles. The study is further complemented by large-signal time-domain simulations where structures for several applications are discussed.