TGG (Terbium Gallium Garnet)
Applications
Faraday Rotators and Isolators
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.
| Material Properties | |
| Formula | Tb3Ga5O12 |
| Crystal Structure | [111] |
| Extinction Ratio (over 2/3 clear aperture) |
30 dB |
| Verdet Constant (632 nm) | -134 RadT-1m-1 |
| Verdet Constant (1064 nm) | -40 RadT-1m-1 |
| Thermal Conductivity | 7.4 W cm-1 K-1 |
| Refractive Index | 1.95 |
| Nonlinear Index, n2 | 8.0 |
| Figure of Merit, V/a | 27 |
| Figure of Merit, V/n2 | 5 |
| Tolerances | |
| Wavefront Distortion (per inch of rod length) | l/8 |
| Diameter | +0.000" / -0.002" |
| Length | +0.010" / -0.010" |
| Chamfer | 0.005" ± 0.003" at 45° ± 5° |
| Flatness | <l/10 at 633nm |
| Parallelism | < 1 arc minute |
| Perpendicularity | < 10 arc minutes |
| Surface Quality (per MIL-O-1380A) |
10-5 Scratch-Dig |
| AR Coating Reflectivity | <0.25% @1064nm |
| Coating Adhesion/Durability | Meets MIL-C48497A |
| Barrel Finish (10-6 inches) | 55 ± 5 |