Crystals Land

  AgGaS₂ & AgGaSe₂

Silver Gallium Sulfide (AgGaS₂) and Silver Gallium Selenite (AgGaSe₂) crystals have attained special interest for the middle and deep infrared (IR) applications due to its large nonlinear optical (NLO) coefficients and high transmission in the IR region. The phase matching and transmission characteristics of AgGaS₂ allow 3-wave interactions in the mid and near IR.AgGaS₂ has been used as an efficient NLO crystal for 3 - 10 mm IR output, particularly for OPO devices pumped with Nd:YAG laser, frequency mixing of OPO outputs pumped by Ti:Sapphire or Nd:YAG laser, as well as frequency mixing Nd:YAG laser with dye and Ti:Sapphire or other laser sources. AgGaS₂ has also been demonstrated to be an efficient frequency doubling crystal for infrared radiation such as 10.6 mm output of CO₂ lasers.

Physical Properties:

	AgGaS2	AgGaSe2
Crystal Structure	Tetragonal	Tetragonal
Cell Parameters(A)	a=5.756, c=10.301	a=5.992, c=10.886
Melting Point(ºC)	997	581
Density(g/cm3)	4.702	5.700
Absorption Coefficient(cm-1) @ 1.064mm @ 10.6mm	0.01 0.6	< 0.05 < 0.02
Resistance	>1012
Relative Dielectric Constant e11s/eo @ 25 MHz e11s/eo @ 25 MHz	10 14	10.5 12.0
Thermal Expansion Coefficient (10-3/ ºC) ||C ^C	+12.5 -13.2	+16.8 -7.8
Thermal Conductivity (W/cm/ºC)	0.015

Optical Properties:

	AgGaS2		AgGaSe2
Transparency Range(μm)	0.50-13.2		0.78-18.0
Phase-Matching SHG range(mm)	1.8-11.2		3.1-12.8
Thermo-Optic Coefficient dno/dt(10-5/ºC) dne/dt(10-5/ºC)	15.4 15.5		~15 ~15
Linear Electro-optic Coefficients g41T g63T	4.0+/-0.2 3.0+/-0.1		4.5@1.15mm 3.9@1.15mm
Relative Indices @ 1.064mm @ 5.300mm @ 10.60mm	no 2.4521 2.3945 2.3472	ne 2.3990 2.3408 2.2934	no 2.7010 2.6134 2.5912	no 2.6792 2.5808 2.5579
NLO Susceptibilities d36(pm/V) SHG @ 10.64 mm	18		58
Relative Indices @ ~ 10ns, 1.064mm @ ~ 10ns, 10.6mm	25,surface >500 bulk		20-30,surface
Wavelength @no=ne(mm)	0.4974		0.811
Sellmeier Equations(λ in μm)
AgGaS2	no2 (l)= 3.3970 + 2.3982/(1 - 0.09311/l2) + 2.1640/(1 - 950/l2) ne2 (l)= 3.5873 + 1.9533/(1 - 0.11066/l2) + 2.3391/(1 - 1030.7/l2)
AgGaSe2	no2 (l)= 4.6453 + 2.2057/(1 - 0.1879/l2) + 1.8577/(1 - 1600/l2) ne2 (l)= 5.2912 + 1.3970/(1 - 0.2845/l2) + 1.9282/(1 - 16007/l2)

Specifications:

Dimension Tolerance	±0.1mm
Flatness	λ/8@633nm
S/D	10/5 to MIL-O-13830A
Parallelism	20"
Perpendicularity	5 arc minutes
Angle Tolerance	Δθ<0.5°Δj>0.5