What is Optocoupler? All Questions › Category: Analog Electronics › What is Optocoupler? 0 Vote Up Vote Down chetan shidling asked 4 years ago I need short information. 1 Answers 0 Vote Up Vote Down chetan shidling answered 4 years ago The optocoupler consist of LED and LDR. When supply is given to the LED the light will fall on LDR and thus circuit will become close. It is used as protective device in many applications.