Double heterostructure opto-electronic switch (DOES) analysis and its application for photonic analog-to-digital conversion

Date of Completion

January 2001


Engineering, Electronics and Electrical




The Double Heterostructure Opto-Electronic Switch (DOES) based on inversion channel technology has been modeled in its different operating conditions. First, the equilibrium condition has been calculated. The important charge and voltage parameters are investigated with the variation of the major doping concentrations. The results help to understand the device structure and its tradeoffs and are used as boundary conditions for on state and lasing condition calculations. ^ The model for the on state and switch-off condition has been developed by coupling the current continuity equations with the charge and voltage relations. The closed form results for the electron and hole densities, the critical voltages and all the current components have been obtained in terms of the applied voltage and the device parameters. Using the fact that the V-I characteristic must exhibit a minimum at the holding point, the on-state termination condition is determined. The switch-off condition is investigated by adding a third terminal current which removes the electrons from the quantum well. ^ A theory for the lasing characteristics of the DOES has been developed. Combining the conduction of the DOES with the Fermi energy approach to the laser, a model for the DOES as a laser has been derived. The laser threshold current is determined in terms of the device structure and optical properties. The model validity is verified by comparison to experimental data. ^ A novel approach for optical A/D conversion based on the optoelectronic thyristor has been introduced using the unique properties of optical and electrical bistability. As a basic unit in A/D conversion, the photonic smart comparator has been described. The different A/D converter architectures and the potential performances have been investigated. The smart comparator has been demonstrated and multi-bit optical A/D conversion has been implemented. ^