Opto-isolator
![Schematic diagram of an opto-isolator showing source of light (LED) on the left, dielectric barrier in the center, and sensor (phototransistor) on the right.[note 1]](/Images/godic/202502/02/Optoisolator_Pinout.svg1602.png")
![Planar (top) and silicone dome (bottom) layouts - cross-section through a standard dual in-line package. Relative sizes of LED (red) and sensor (green) are exaggerated.[note 2]](/Images/godic/202502/02/Optoisolator_topologies_both.svg1602.png")
![A fast photodiode opto-isolator with an output-side amplifier circuit.](/Images/godic/202502/02/Optically_isolated1602.jpg")
In electronics, an opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is a component that transfers electrical signals between two isolated circuits by using light. Opto-isolators prevent high voltages from affecting the system receiving the signal. Commercially available opto-isolators withstand input-to-output voltages up to 10 kV and voltage transients with speeds up to 10 kV/μs.