The device is also known as opto-isolator since no current is involved between the two chips, rather only light signals, and also because the IR emitter and IR detector feature a 100% electrically insulation and isolation. The main purpose of an optocoupler. An optocoupler (or opto-isolator) is a component that transfer signals between circuits using light. In this guide, you'll learn how they work and how you can use one in your own projects.