Terbium Gallium Garnet(TGG) The magneto-optical crystal TGG is an optimum material for Faraday devices (Rotator and Isolator) in the range from 400nm-1100nm, excluding 470-500nm.The Faraday rotator consists of a TGG rod contained inside a special designed magnet. The rotation sense of the polarization of a light beam passing through the rotator only depends on the direction of the magnetic field and not on the direction of propagation of the light beam. The optical isolator is a Faraday rotator set between two suitably aligned polarizers which allows a light beam to pass through in one direction only. TGG has a combination of excellent properties such as large Verdet constant, low light loss, high thermal conductance and high light damage threshold which makes it a unique material for Faraday devices particularly suitable for YAG lasers and Ti: sapphire tunable lasers, ring lasers and seed injected lasers. Crystal Parameters:
Chemical Formula |
Tb 3 Ga 5 O 12 |
Lattice Parameter |
a=12.355Å |
Growth Method |
Czocralski |
Density |
7.13g/cm 3 |
Mohs Hardness |
8.0 |
Melting Point |
1725 o C |
Refractive Index |
1.954 at 1064nm |
Thermal Conductivity |
9.4x10 -6oC -1 |
Verdet Constant |
0.12min/Oe.cm at 1064nm |
Standard TGG rod specification:
Crystal rod parameters: |
Orientation |
[111] within 5 degrees |
Wave front Distortion |
< l /8 wave |
Extinction Ratio |
> 30dB |
Dimensional Tolerances: |
Diameter |
+0.00mm/-0.05mm |
Length |
+0.2mm/-0.2mm |
Chamfer |
0.13mm (+0.00mm,-0.08mm) at 45º +/- 5º |
End Configuration: |
Flatness |
< l /10 wave at 633nm |
Parallelism |
< 1 minutes of arc |
Perpendicularity |
< 30' |
Scratch-dig |
10/5 per MIL-O13830A |