An optocoupler, or optical coupler, is a semiconductor device that transmits electrical signals between isolated circuits using light. It consists of an LED (light-emitting diode) and a photosensitive component (e.g., phototransistor) enclosed in a single package. When an electrical signal triggers the LED to emit light, the photosensitive component detects the light and converts it back into an electrical signal—enabling signal transfer without direct electrical contact. This design blocks voltage spikes, noise, and ground loops, making it ideal for isolating high-voltage circuits from low-voltage systems in power supplies, industrial controls, and medical devices.

A Drive Opto-Coupler (sometimes referred to as a "driving optoisolator") is a type of opto-coupler specifically engineered to transmit control signals while providing the necessary power or current to drive other electronic components, such as switches, transistors, or actuators. It combines the core function of optical isolation (separating input and output circuits galvanically) with a built-in output stage capable of delivering sufficient drive capability to operate downstream devices. Unlike basic signal opto-couplers, which primarily transmit low-power signals, drive opto-couplers include an integrated output driver (often a transistor or amplifier) that can supply higher current or voltage to "drive" loads. For example, they may deliver enough current to trigger relays, activate power transistors, or control solenoids.