TGG:
TGG (Terbium Gallium Garnet) is an excellent magneto-optical crystal used in various Faraday devices(Polarizer and Isolator) in the range of 400nm-1100nm, excluding 475-500nm.

Advantages:
TGG has twice the Verdet constant of a terbium-doped glass.
The thermal conductivity of crystalline TGG is an order of magnitude greater than a typical glass.
Optical losses are lower for TGG than Tb-doped glasses.
The combination of the above factors make TGG better suited to high average power applications. The principal limiting factor is thermally induced beam distortion. Beam distortion is less for TGG than Tb-doped glasses under the same power loading level.