Faraday Optical Isolators (633 nm)

A Faraday isolator (FI) is a nonreciprocal optical device which transmits the linearly polarized light in one direction and deflects the backward beam. It usually consists of a Faraday rotator and two polarizers. The Faraday rotator is made of magneto-optical active material which is placed into the permanent magnet system (Nd-Fe-B). Two types of the magneto-optical active materials are available: Terbium-doped glass, Terbium-Gallium-Garnet (TGG) crystals. The isolator protects a laser source by attenuating the reflected and backscattered light by several orders of magnitude (10^6 to 10^6). It is also used when some devices have extreme sensitivity to optical feedback which can cause intensity instabilities, frequency pulling and other undesirable effects.