Optocouplers (photo couplers) are mainly classified according to the type of detector on the output side, signal transmission characteristics and functions as follows:Transistor optocouplersDarlington optocouplersBidirectional thyristor drive optocouplersMOS drive type optocouplers
MOSFET output type optocouplers (opto-relays)
Thyristor output type optocouplers (SSR solid state relays)
Linear and nonlinear optocouplers
High-speed optocouplers, etc.