Abstract: A solid-state, four terminal optical relay has a current regulator with two input pins, and an output switch with two output pins. The relay includes an optical isolator assembly so that the current which causes switching of the relay is optically, rather than electrically, transmitted to an output switch driver. The relay includes an internal current overload detect and latch circuit which operates if the relay is switched on into a shorted load, or if a short is switched in across the load while the relay is on. The current overload detect and latch circuit is sufficiently fast to permit the relay to be continuously pulsed into a shorted load without damage to the relay.