Optocouplers, also referred to as photocouplers, optoisolators, or optical isolators, are electronic components that transfer electrical signals between two isolated circuits through the use of light. They typically consist of a light-emitting diode (LED) and a photosensitive detector, such as a phototransistor, encapsulated in a single package. When the input side receives an electrical signal, the LED emits light, which is detected by the output side to reproduce the signal without any direct electrical connection.

This optical isolation helps prevent high voltages or electrical noise from affecting the receiving circuit. Optocouplers are commonly used in power supplies, communication interfaces, signal isolation, and control systems.