HOW THE ISOLATOR WORKS
OFR isolators are used to reduce or eliminate the effects of optical feedback - reflections of the laser's energy back into itself. These effects include noise, amplitude fluctuation, and even laser damage .
OFR isolators protect the laser, while maintaining beam alignment and providing maximum forward transmission and reverse isolation.
An isolator consists of a Faraday rotator, two polarizers and a housing. The Faraday rotator consists of a magneto-optic material within a magnetic field.
The forward mode: Laser light enters the isolator via the input polarizer and is linearly polarized. It then enters the rotator, which rotates its plane of polarization 45 ° . It then exits via the output polarizer, whose axis is 45 ° from the input plane of polarization.
The reverse mode: Some random beam reflections will be reflected back towards the laser. This feedback re-enters the isolator via the output polarizer and is polarized at 45 ° . It continues into the rotator and is rotated by another 45 ° . The feedback, now polarized at 90 ° relative to the input polarizer, is extinguished.
The laser is now isolated from its own reflections.