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A
closely related crystal to Silver Thiogallate (AgGaS2 or
AGS), Silver Selenogallate (AgGaSe2 or AGSe) is
also available. AgGaSe2 has band edges at 0.71 and 18 µm.
Its bulk quality is excellent across the transmission range. There
is no residual e-ray absorption centred around 1800 nm. The phase
matching and non-linear optical properties of AgGaSe2 allow
various SFM/DFM interactions from the visible to mid-IR. These includes
non-critically phase matched DFM using selected wavelengths (available
from tunable dye and Ti:Sapphire lasers) and OPO's pumped with commonly
available Nd:YAG lasers.Tuning within 2.5–12 µm was obtained
when pumped by Ho:YLF laser at 2.05 µm; NCPM operation within
1.9–5.5 µm was achieved pumping at 1.4–1.55 µm.
Efficient SHG of pulsed CO2 laser is demonstrated. The AgGaSe2
crystals are also used for frequency doubling and three-frequency
mixing. The parametric oscillators on the base of those crystals can
produce the continuously tunable radiation in the spectral range from
1.34 mm to 18 mm with suitable pump laser. The low absorption of our
AgGaSe2 crystals results in the fact that 80 mm length
element has transmission value of 66.4% on a 1.06 mm wavelength, which
is in accordance with the theoretical value of Fresnel loses for the
crystal without of any absorption. With those crystals, the record
results of conversion efficiency in comparison with all known infrared
materials have been obtained. SHG efficiency of CO2 laser
radiation for 40 mm length elements was about 20% (pulse length –
80 ns, pump energy - 2 J).
APPLICATIONS:
• Generation second harmonics on CO and CO2
- lasers
• Optical parametric oscilator
• Different frequency generator to middle infrared
regions up to 17 mkm.
• Frequency mixing in the middle IR region
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MAIN
PROPERTIES:
| Transparency
range, µm |
0.71
- 18 |
| Point
group |
4m2 |
| Lattice
parameters, Å |
a
= 5.9921, c = 10.883 Å |
| Density,
g/cm3 |
5.71 |
| Mohs
hardness |
3.0
- 3.5 |
| Refractive
indexes: |
|
| at
1.06 µm |
no
= 2.7010; ne = 2.6792 |
| at
3.0 µm |
no
= 2.6245; ne = 2.5925 |
| at
5.3 µm |
no
= 2.6134; ne = 2.5808 |
| at
10.6 µm |
no
= 2.5912; ne = 2.5579 |
| at
12 µm |
no
= 2.5837; ne = 2.5505 |
| Non-linear
coefficient at 10.6 µm, pm/V |
d36
= 33 |
| Walk
off |
0.68°
at 5.3 µm |
| Optical
damage threshold at 10.6 µm, 150 ns, MW/cm2 |
10
- 20 |
| Thermal
expansion coefficient |
|
| parallel
to c-axis |
16.8
x 10-6 x °C-1 |
| perpendicular
to c-axis |
-7.8
x 10-6 x °C-1 |
We supply AGSe
optical elements made according to customers' order.
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