Some specific optical parameters of Gallium-Garnet (TGG) crystal are as follows: 

Wavelength coverage: 500nm - 3000nm.

Refractive index: 2.03.

Verdet constant: 0.12 min/Oe·cm at a wavelength of 1064nm.

Wavefront distortion: <1/8 wave total (measured at 633nm).

Extinction ratio: >30 dB.

Planarity: <1/10 wave at 633nm.