1.55 um PnpN optical thyristor as a smart optical switch has potential applications in advanced optical communication systems. It can be used as a header processor in optical asynchronous transfer mode (ATM) and as a hard limiter in optical code division multiple access (CDMA) system. For those applications, however, relatively slow switching speed of the optical thyristor is the major limiting factor. To enhance the switching characteristics, depleted optical thyristor (DOT) has been proposed, in which majority carriers in the center n- and p-layers can be fully depleted by applying a reverse-bias pulse. Recently, we proposed a novel waveguide type 1.55 micrometer InGaAsP/InP DOTs. In this presentation, using the finite difference method (FDM), we calculate the effects of such parameters as doping concentration, thickness of the outer and inner layers of the thyristor to find out the optimized structure in the view of fast and low power consuming operation, low reverse full-depletion voltage, high optical confinement factor. With these results, a waveguide type 1.55 micrometer DOT is fabricated with metal organic chemical vapor deposition (MOCVD) and measured on the switching voltage with the size. The results of the simulation are compared with those of the experiment.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.