A semiconductor laser coupled to an external cavity is investigated using a composite-cavity mode approach. Strong frequency hopping for small cavity length changes is obtained, indicating instability of the laser operation against cavity lengths fluctuations.
In the radiation-hardened, optically triggered thyristor development being carried out jointly by Organizations 1141 and 2531, a theoretical model was needed to assist in designing the devices. This model had to accurately predict thyristor performance (e.g., breakover voltage and holding current) for different fabrication and experimental parameters such as doping, layer thickness, temperature, and incident optical intensity. This report describes a mode we are currently developing that is based on treating a p-n-p-n thyristor as coupled p-n-p and n-p-n transistors. This approach has the advantages of providing tractability of the physics that govern thyristor behavior without requiring extensive numerical computations. When benchmarked by a more rigorous (and, consequently, computationally more complicated) treatment, our model should provide accurate and fast screening of a wide range of thyristor configurations. Section 2 describes the general thyristor configuration we wish to investigate. The derivation of the basic equations for our thyristor model is presented in Sections 3. These equations depends on the saturation currents and multiplication factors at each p-n junction, and on the current gains of p-n-p and n-p-n transistors.