TGG(Terbium gallium garnet) single crystal is the best magneto-optical material for making Faraday polarifiers and isolators, suitable for wavelengths of 400-1100nm (excluding 470nm-500nm). The Faraday polarimeter consists of a TGG crystal rod and a specially designed magnet. The polarization direction of the beam passing through the magneto-optical material will be deflected under the action of the magnetic field, and the deflection direction is only related to the magnetic field direction, and has nothing to do with the beam propagation direction. The optical isolator consists of a 45-degree deflected polarifier and a pair of suitably placed polarizers that allow the beam to pass in only one direction, blocking the beam that travels in the opposite direction.