AgGaS2 crystals
Main features
- Unique non-linear properties across the transmission range from 0,5 to 12 µm
- Low optical absorption and scattering
- Transparency at short wavelengths
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
- Standard specifications
Silver Thiogallate (AgGaS2, AGS) has been demonstrated as an efficient crystal for nonlinear parametric interactions in the infrared spectral range. Its transparency region ranges 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. High transparency in the short wavelength range beginning at 550 nm is used in OPOs pumped by Nd:YAG laser.
Using 2050 nm pump laser, an optimally designed AgGaS2 OPO 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 features a high non-linear coefficient, high damage threshold, and a wide transmission range. It also exhibits a low optical absorption and scattering, low wavefront distortion. AgGaS2 has the highest figure of merit for non-linear interactions in the near and deep infrared.
| 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 | 0,47 - 13 µm @”0“ transmittance level |
| Sellmeier equations @T = 293 K (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 | no = 2,3471; ne = 2,2914 @ 10,6321 µm |
| Thermal conductivity | 1,4 (||c) Wm-1K-1, 1,5 (⊥ c) Wm-1K-1 |
| AgGaS2 crystals | |
|---|---|
| Orientation accuracy | <30 arcmin |
| Clear aperture | 85% |
| Face dimensions tolerance | +0,0/-0,2 mm |
| Parallelism error | <30 arcsec |
| Perpendicularity error | <10 arcmin |
| Protective chamfers | <0,2 mm at 45° |
| Surface quality | 60-40 S-D |
| Coatings | BBAR/BBAR@1,2-2,6 µm/2,6-11 µm |
| Mount | Unmounted |
