Research On A Dual-wavelength Single Longitudinal Mode Semiconductor Laser Based On Microring Resonators

With the advantages of small volume, simple structure, high integration density and low insertion loss, microring resonators are widely used in optical integrated devices. Microring resonator acts mainly as a longitudinal mode selector in a laser. If two microrings are cascaded, free spectral range (FSR) can be extended as a result of vernier effect. THz radiation has broad application prospects in lots of fields owing to its special position in the frequency spectrum. In this thesis, a semiconductor laser based on microring resonators is designed. The laser can emit dual-wavelength single longitudinal mode light for generating THz signals by the way of frequency beating. The major research achievements are as the following:(1) The research background and significance of THz radiation is introduced. Applications of microring resonators are presented. A novel dual-wavelength semiconductor laser based on double ring structure is proposed, which can be used to generate THz signals.(2) Mode distribution in stripe waveguides is researched. Mode distribution of E_mn^y mode is simulated by solving characteristic equations. Both basic mode and high order modes exist when the size of the stripe waveguide is large, and only basic mode exists when the size of the stripe waveguide is small. Mode distribution in a bent waveguide, and the effect of the size of the bent waveguide to the distribution is analyzed.(3) The resonance condition for a microring is analyzed. To take lateral coupled microring and bus waveguide for an example, the relation between the coupling efficiency and the propagation distance and relation between the coupling ratio and the size of the waveguide is analyzed and simulated. The way for directional control of counter propagating lights in microrings is researched.(4) Filtering characteristics of an add/drop ring and cascaded rings are researched, based on which a novel dual-wavelength single longitudinal mode tunable semiconductor laser is presented. Theoretical model of the designed laser is presented and threshold characteristics, dynamic characteristics and stable state characteristics of it is researched.(5) Different types of material are compared, and InGaAsP/InP material is finally chosen to fabricate the laser. Fabrication of lateral coupled passive/active microring resonators and mixed construction with passive parts and active parts is researched, and the fabrication method of the designed laser is proposed.