AgGaS2 crystals
Main features
- Unique non-linear properties across the transmission range 0,5 to 12 μm
- Low optical absorption and scattering
- Short wavelength transparency
Application examples
- Frequency mixing in the middle IR region from 4,0 to 18,3 μm
- Second harmonic generation and up-conversion for CO2 lasers
- Tunable OPO for solid-state lasers
- Description
- Properties
- Specifications
Silver Thiogallate (AgGaS2, AGS) has been demonstrated as an efficient crystal for nonlinear parametric interactions in infrared spectral range. Its transparent region is from 0,53 to 12 μm. AGS based optical parametric oscillators feature continuously tunable radiation over a wide range of wavelengths in the infrared spectral range. Its high short wavelength transparency beginning at 550 nm is used in optical parametric oscillators pumped by Nd:YAG lasers. Using 2050 nm pump laser, an optimally designed AGS optical parametric oscillator is tunable from about 2,5 to 12,0 μm. The output range can be extended by the sum or difference frequency mixing (SFM/DFM). This crystal has a high non-linear coefficient, high damage threshold, and a wide transmission range. It also has low optical absorption and scattering, low wavefront distortion. AGS has the highest figure of merit for non-linear interactions in the near and deep infrared. AGS is transparent from 0,53 to 12 μm.
| Physical and optical properties | |
|---|---|
| Chemical formula | AgGaS2 |
| Crystal structure | Tetragonal, 42m |
| Lattice parameters | a = 5,742 Å, c = 10,26 Å |
| Optical symmetry | Negative uniaxial (no > ne, λ<0,497 μm ne > no) |
| Density | 4,58 g/cm3 |
| Mohs hardness | 3-3,5 |
| Transparency range @"0" transmittance level | 0,47 - 13 μm |
| Sellmeier equations @0,54 - 12,9 μm (λ in μm) | no2 = 5,79419 + 0,23114/(λ2 - 0,06882) - 2,4534×10-3 λ2 + 3,1814×10-7 λ4 - 9,7051×10-9 λ6; ne2 = 5,54120 + 0,22041/(λ2 - 0,09824) - 2,5240×10-3 λ2 + 3,6214×10-7 λ4 - 8,3605×10-9 λ6 |
| Refractive indices @10,6321 μm | no = 2,3471, ne = 2,2914 |
| Thermal conductivity @T = 293 K | 1,4 (||c) Wm-1K-1, 1,5 (⊥ c) Wm-1K-1 |
| AgGaS2 crystals | |
|---|---|
| Clear aperture | 85% |
| Face dimensions tolerance | +0/-0,2 mm |
| Thickness tolerance | ±0,2 mm |
| Parallelism error | <30 arcsec |
| Protective chamfers | <0,2 mm at 45° |
| Surface quality | 20-10 S-D |
| Wavefront distortion | <λ/[email protected],8 nm |
| Coatings | BBAR/[email protected],2-2,4 μm/2,4-11 μm |
| Laser induced damage threshold | >350 MW/cm2@1064 nm, 10 ns |
| Mount | Unmounted |
