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Silver
Thiogallate (AgGaS2 or AGS) is transparent from 0.53
to 12 µm and has been demonstrated to be an efficient frequency
doubling crystal for infrared radiation, such as the 10.6 µm output
of CO2 lasers. Although nonlinear optical coefficient is
the lowest among the above mentioned infrared crystals, its high short
wavelength transparency edging at 550 nm is used in OPOs pumped by Nd:YAG
laser in numerous difference frequency mixing experiments using diode,
Ti:Sapphire, Nd:YAG and IR dye lasers covering 3–12 µm range,
direct infrared countermeasure systems, and SHG of CO2 laser.
With suitable pump lasers, AgGaS2 optical parametric
oscillators (OPO's) can produce continuously tunable radiation over
a wide range of wavelengths in the infrared. Using a 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 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. Among commercially
available crystals, AgGaS2 has the highest figure of merit
for non-linear interactions in the near and deep infrared. The availability
of this crystal has stimulated new activities exploiting its interesting
properties. Potential applications include wavelength selectable medical
procedures and a wide variety of spectroscopic applications. It is useful
for high performance IR waveplates. It has also been shown as an excellent
crystal for non-linear three-wave interactions.
APPLICATIONS:
• Generation second harmonics on CO and CO2
- lasers
• Optical parametric oscilator
• Different frequency generator to middle infrared
regions up to 12 mkm.
• Frequency mixing in the middle IR region from 4.0
to 18.3 µm
• Tuneable solid state lasers (OPO pumped by Nd:YAG
and others lasers operating in 1200 to 10000 nm region with efficiency
0.1 to 10 %)
• Optical narrow-band filters in the region near isotropic
point (0.4974 m at 300 °K), transmission band being tuned at temperature
variation
• Up-conversion of CO2 laser radiation image
into near-IR or visible region by using/ or use of Nd:YAG, ruby or dye
lasers with efficiency up to 30 % |
MAIN
PROPERTIES:
| Transparency
range, µm |
0.47
- 13 |
| Point
group |
4m2 |
| Lattice
parameters, Å |
a = 5.757, c = 10.311 Å |
| Density,
g/cm3 |
4.58 |
| Mohs
hardness |
3.0 -
3.5 |
| Refractive
indexes: |
|
| at 1.06
µm |
no
= 2.4521; ne = 2.3990 |
| at 3.0
µm |
no
= 2.4080; ne = 2.3545 |
| at 5.3
µm |
no
= 2.3945; ne = 2.3408 |
| at 10.6
µm |
no
= 2.3472; ne = 2.2934 |
| at 12
µm |
no
= 2.3266; ne = 2.2716 |
| Non-linear
coefficient at 10.6 µm, pm/V |
d36 = 12.5 pm/V |
| Optical
damage threshold at 10.6 µm, 150 ns, MW/cm2 |
10 -
20 |
| Walk off |
0.76° at 5.3 µm |
| Thermal
expansion coefficient |
|
| parallel
to c-axis |
12.5
x 10-6 x °C-1 |
| perpendicular
to c-axis |
-13.2
x 10-6 x °C-1 |
We supply AGS optical
elements made according to customers' order.
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