Characterization of the Dynamics of Optically-Injected Nanostructure Lasers

The direct-modulation of semiconductor lasers is the simplest and most compact approach to pass data onto an optical fiber; however, their intrinsic limitations under direct-modulation such as wavelength chirp and inherent relaxation oscillation frequency constraints impede their high-speed and long-distance capabilities. The injection-locking of semiconductor lasers improves the injected laser's operational characteristics under direct-modulation, attracting a large degree of interest over the past decade. These improvements include increasing the modulation bandwidth through the enhancement of the resonance frequency, suppressing nonlinear distortion, and reducing relative intensity noise, mode-hopping, and chirp. The nonlinear dynamics associated with optically-injected semiconductor lasers has also attracted great interest due to potential applications including: all-optical amplitude-modulation to frequency-modulation conversion, chaotic-communication, and photonic microwave generation. In this dissertation, the optical-injection of quantum-dash and quantum-dot Fabry-Perot semiconductor lasers is investigated in the context of modeling the impact of their characteristically large nonlinear gain component. The impact of the large degree of gain compression on the differential and nonlinear carrier relaxation rates observed in nanostructure lasers under large operational photon densities is also investigated under strong optical-injection conditions. A novel small-signal microwave modulation response function is derived and shown to improve upon current models at modeling the microwave modulation response under optical-injection. The nonlinear dynamics observed under weak injection strengths are theoretically analyzed using a novel dimensionless rate equation model where including the impact of the nonlinear carrier relaxation rate is shown to improve the agreement with experimentally collected data. The novel tools derived to analyze the operation of the optically-injected system encompass the physical nature of the injected laser in a more complete manner than previously derived approaches. Theoretical predictions derived here show that large nonlinear carrier relaxation rates, along with suitably small linewidth enhancement parameter values of nanostructure lasers suppress the instability of the optically-injected system. The quantum-dash laser’s potential for implementation as a tunable photonic oscillator for use in radio-over-fiber applications or directly-modulated slave laser in a coherent optical communication system is described, along with the quantum-dot laser’s highly stable operation under optical-injection.EngineeringDoctoralUniversity of New Mexico. Dept. of Electrical and Computer EngineeringLester, LukeKoch, StevenZarkesh-Ha, PaymanOsinski, Mare