Abstract : A novel fully depleted optical thyristor (DOT) using quarter wavelength reflector stacks (QWRS) is proposed. QWRS are employed as bottom mirrors to enhance the emission efficiency as well as optical sensitivity. To analyze their switching characteristics, s-shapes nonlinear current–voltage curves were simulated and the reverse full-depletion voltages (Vnegs) of DOTs were obtained as a function of semiconductor parameters using a finite difference method associated with a currentoriented method. The fabricated DOTs show sufficient nonlinear s-shaped current–voltage (I–V) characteristics, and switching voltage changes with and without bottom mirrors are 1.82V and 1.52 V, respectively. Compared to a conventional DOT, this device with the bottom mirror shows about 20% and 20–50% enhancement in switching voltage changes and spontaneous emission efficiency, respectively.