(Optical Coupler, the abbreviation OC),also known as optical isolators, or optocoupler. Optocouplertransmit electrical signals to light as a medium. Its input and outputelectric signals with good isolation effect, so it is widely applied inthe various circuits. Atpresent, it has become the most species, one of the most versatileoptoelectronic devices. The optocoupler general consists of three parts: theemission of light, the light receiver and signal amplification. Theinput electrical signal for driving the light emitting diode (LED), so that theissuance of certain wavelengths of light by the optical detector receives light current,and then after further amplified output. It will also grow rapidly.

It needs to transmitinformation through an insulating layer, but does not allow the physicalelectrical contact in some occasions, usually it needs some isolation device,transmission of different ways in accordance with the signal through theinsulating layer, there are several types of the isolator can be selected,which is more common isby the way of the light transmission, such isolationdevice called optocouplers. Optocoupler composition by including alight-emitting diode (LED), light detector and the other input and output codeccircuit.

The input electrical signalfor driving the light emitting diode (LED), so that the issuance of certainwavelengths of light by the optical detector receives light current, and then outputs after further amplified.This completes the conversion of electricity - light - electricity, which playthe roles of input, output and isolation. Optocoupler mutual isolation betweenthe input and output signal transmission with unidirectional characteristics,and thus has good electrical insulating ability and anti-interference ability.Also, the input terminal of the photocoupler is a current type of lowresistance element, which has a strong common mode rejection capability.Therefore, it is in the long-term transmission of information as a terminalisolation components can greatly improve the signal-to-noise ratio. In computerdigital communications and real-time control as signal isolation interfacedevices, can greatly increase the reliability of the computer work.