An optocoupler is a coupling device used to couple optical signals. In this guide, you'll learn how they work and how you can use one in your own projects. Optocouplers are very useful when you need to isolate different sections of a circuit, for example in power. These components are called optocouplers or optoisolators or simply optos, and they perform the crucial function of passing signals between isolated sections of circuitry. Commercially. Optocouplers, also known as opto-isolators, uses infrared light to transfer electrical signals between two electrically isolated circuits and are commonly classified by their photosensitive output device What is an Optocoupler? An optocoupler (also called an opto-isolator, photo-coupler, or optical.