We propose and analyze novel fully depleted optical thyristors (DOTs) using multiple quantum wells (MQWs) and quarter- wavelength reflector stacks (QWRSs). MQWs are employed to enhance the absorption, while a QWRS is employed as a bottom mirror to enhance the emission efficiency as well as the optical sensitivity. In order to analyze the switching characteristics, we simulate S-shaped nonlinear current-voltage curves using a coupled junction model associated with the current-oriented method. Furthermore, emission characteristics are obtained by using the scattering-matrix method and the van Roosbroeck-Shockley relation. According to our analysis, the novel DOTs significantly improve the switching and light emission characteristics. Compared to a conventional DOT, the optical switching energy and the bit rate of the novel DOT using both mQws and a QWRS are improved by a factor of 0.45 and 1.61, respectively, for a cascading operation. We also analyze the performances of free-space optical interconnects using the novel DOTs.