TGG Crystal, or Terbium Gallium Garnet Crystal, with chemical composition TbGa5O12, as a synthetic garnet, is the most prevalent magneto-optical material used to manufacture Faraday rotators and various magneto-optical components.

As the most common magneto-optical crystal used for making Faraday rotators and isolators, TGG features ideal optical transparency with its transmission range from visible to near-infrared (400-1100nm, excluding 475-500nm) and large Verdet constant. The Verdet constants for TGG are -134 Rad T^-1 m^-1 at 632.8nm and -40 Rad T^-1 m^-1 at 1064 nm. The substantial Verdet constants result in the Faraday effects. Through locating a TGG crystal rod in a strong magnetic field, a Faraday rotator can be obtained, which introduces non-reciprocal, over 45° Faraday rotation in polarization. This rotation in polarization is the core principle of a Faraday optical isolator. And with its function of rotation on the polarization plane, a lot of optical devices, besides isolators, could also be contrived, such as magneto-optical modulators, circulators, current measuring transducers, etc. 

Other characteristics of TGG  are also desirable, including superb thermal properties (thermal conductivity 7.4w/m/k), low optical losses (<0.1%/cm), and high laser-induced damage thresholds (>1 GW/cm2). These advantages in total make TGG crystals perform better when coping with high average power fiber lasers than terbium-doped glasses in terms of greater Verdet constant and lower optical losses.

Shanghai North Optics supplies and sales Custom Czochralski-grown, precision-polished Terbium Gallium Garnet (TGG) Crystals with high surface quality (10/5 S/D) and high transmission AR Coatings, realizing strong magneto-optical effects with effective light-blocking functions in the lasers meanwhile ensuring small optical loss. Our manufacturing and sales expertise enables us to provide exceptional TGG crystals at a competitive price.