Investigation of Components in Integrated Optoelectronic Circuits

This thesis includes a series of studies on passive and active components for integrated optical circuits. For the passive structures, a boundary integral method is developed to give full wave solutions to unbounded propagation problems. Passive optical waveguide structures such as large angle bends and T-branches are successfully modeled including all scattering and reflection effects. The full wave solution enables us to characterize the radiation loss and tolerance to fabrication errors. Therefore, compact, low loss designs for waveguide bends and T-branches can be achieved. The boundary integral method has also been used to analyze other important structures such as waveguide cross, reflectors and cavities. In the active device, we proposed, designed and fabricated a lateral current injection (LCI) ridge waveguide laser on semi-insulating GaAs substrate. This LCI design combines the ridge waveguide and a lateral p -n junction formed by selective zinc diffusion. The ridge waveguide gives rise to two advantages: a stable lateral mode control and reduction of the thermal diffusion time. Lasing operation is achieved with a threshold current of 27 mA under continuous wave (CW) and 18 mA under pulsed operation. Large reduction in threshold current is expected with improved material quality. The LCI ridge laser is well suited as an active component for optoelectronic integrated circuits (OEIC) on semi-insulating substrates because of its simple fabrication process, compatibility with electronic components, and planar surface profile. This thesis also includes a time domain simulation of passive mode-locked semiconductor lasers using an integrated saturable absorber. The pulse generation and transient process are simulated. The mode -locking conditions and instability due to self-pulsation are investigated.