An optocoupler (also called an opto-isolator, photo-coupler, or optical isolator) is a solid-state semiconductor device that transfers electrical signals between two isolated circuits using optical (photo) coupling of light as the medium. Opto-isolators prevent high voltages from affecting the system receiving the signal. This article provides a thorough exploration of optocouplers (Optoisolator / Photocoupler), including their construction, working principles, advantages. Optocouplers can be described by a variety of different names including optoisolator, and photocoupler. They offer high isolation ratings (5 kV) in a very compact form-factor and, unlike transformers and.