Optical Isolator

Optical isolator is a combination of a polarization Beam splitter cube ( PBS ) and a quarter wave plate made of crystal quartz. Incident light is linearly polarized by PBS and converted to circular polarization by the quarter wave plate, it only allows light to travel in one direction. If any portion of the emerging beam is reflected back into the isolator, the quarter wave plate will convert the reflected beam into a linearly polarized beam which is perpendicular to the input beam. This beam is then blocked by PBS and it will not return to the input side of the system. An optical isolator is an optical component which allows the transmission of light in only one direction. It is typically used to prevent unwanted feedback into an optical oscillator, such as a laser cavity. It is a block optical feedback, with passive isolation of linearly polarized light, it has high isolation.