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AgGaSe2 (AGSe) has been demonstrated to be an efficient frequency doubling crystal for infrared radiation such as the 10.6μm output of CO2 lasers(11). It has also been shown to be an excellent crystal for nonlinear three-wave interactions. With suitable pump lasers, AGSe optical parametric oscillators (OPS's) can produce continuously tunable radiation over a wide range of wavelengths in the infrared. Using a 2.05μm pump laser, an optimally designed AGSe OPO is tunable from about 2.5 to 12μm (26). The output range can be extended by sum or difference frequency mixing (SFM/DFM). Residual e ray absorption centered at 2.1μm may limit average power handling.
This crystal has a high nonlinear coefficient, high damage threshold, and a wide transmission range. It also has low optical absorption and scattering and low wavefront distortion. Among commercially available crystals, AGSe has the highest figure of merit for nonlinear interactions in the near and deep infrared. The availability of this crystal has stimulated new activities exploiting its many interesting properties. Potential applications include wavelength selectable medical procedures, LIDAR, a solid-state equivalent of an IR dye laser, and a wide variety of spectroscopic applications. It is useful for high performance IR waveplates.
A closely related crystal, AgGaS2 (AGS), is also available. Its bulk quality is excellent across the transmission range, except for residual e ray absorption centered around 1.8μm. Surface absorption may increase with time, but the behavior is now greatly improved over that of earlier crystals. The phasematching and nonlinear optical properties of AGS allow various SFM/DFM interactions from the visible to mid-IR. these include 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.
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| Properties of AgGaSe2 and AgGaS2(a) | ||
|---|---|---|
|
|
AgGaS2
(AGS) |
AgGaSe2
(AGSe) |
|
|
|
|
| Structure type(1) | Chalcopyrite | Chalcopyrite |
| Crystal Symmetry and Class | Tetragonal, 2m |
Tetragonal,2m |
| Space Group | I2d |
I2d |
| Lattice Constants (angstroms) | a=5.7566 +/-0.0008
c=10.3016 +/-0.0013 |
a=5.99202 +/-0.0018(2)
c=10.88626 +/-0.0003(2) |
| Density, g/cc | 4.702 | 5.700 |
| Cleavage | (112) good | (112) good |
| Optical Properties |
|
|
Optical Transmission (um)(3)
<3cm-1 |
0.50 to 13.2 | 0.78 to 18.0 |
| Energy Gap(eV),Absorption edge(um) |
|
|
| E perpendicular to c | 2.655, 0.467(21) | 1.713, 0.724 |
| E parallel to c | 2.572, 0.482(22) | 1.689, 0.734 |
Indices of refraction at  (um) |
no(4), ne(4) | no(5), ne(5) |
| 0.589 | 2.5834, 2.5406 | --- |
| 1.064 | 2.4521, 2.3990 | 2.7010, 2.6792 |
| 3.0 | 2.4080, 2.3545 | 2.6245, 2.5925 |
| 5.3 | 2.3945, 2.3408 | 2.6134, 2.5808 |
| 10.6 | 2.3472, 2.2934 | 2.5912, 2.5579 |
| 12.0 | 2.3266, 2.2716 | --- |
| 13.5 | --- | 2.5731, 2.5404 |
| Wavelength where no=ne, um | 0.4974(6) | 0.811(12) |
| dn/dT, 10-6/°C |
|
|
| 1.06um | dno/dT= 167
dne/dT= 176 |
dno/dT= 98(c)
dne/dT= 66(c) |
| 3.39um | dno/dT= 154
dne/dT= 155 |
dno/dT= 74 +/-10(30)
dne/dT= 43 +/-10(30) |
| 10.6um | dno/dT= 149(c)
dne/dT= 156(c) |
dno/dT= 58(c)
dne/dT= 46(c) |
d(ne2 -
no )/dT @  pm
for type I SHG 10.6um |
--- | +/- 1.1(9), -1.2(c) |
| Fresnel Refection Loss per surface |
|
|
| 1.06um | 17% | 21% |
| 10.6um | 16% | 19% |
| Absorption Coeff.
(cm-1)(g) |
|
|
| 1.06um (random) | < 0.01 | < 0.02 |
| 1.8um (e ray) | < 0.10 | < 0.02 |
| 2.1um (e-ray) | < 0.02 | < 0.05 |
| 10.6um (random) | 0.6(b) | < 0.02 |
| Laser Damage Threshold(g,h) |
|
|
| 1.06um, ~10ns pulse (MW/cm2) | sfc 25; bulk >500 | sfc 25 |
| 2.09um, ~50ns pulse (J/cm2)(25) | --- | sfc 0.5-3.0 |
| 10.6um, ~10ns pulse (MW/cm2)(25) | --- | sfc 20-30 |
| 10-20ns pulse (J/cm2)(25) | --- | sfc 0.1-0.2; bulk ~0.2 |
| 200ns pulse (J/cm2)(31) | --- | sfc ~1 |
| NLO Susceptibility d36, pm/V |
|
|
| SHG at 1.064um | 17.5(28) | --- |
| SHG at 10.6um | 11.2(28) | 33(28) |
| Phasematching Range (,um) |
|
|
| Type I SHG | 1.8 to 11.2(4) | 3.1 to 12.8(5) |
| Type II SHG | 2.5 to 7.7(4) | 4.7 to 8.1(5) |
| Phasematching Angle
10.6um Type I SHG |
71.5 (4) |
57.0(c) |
| Birefringence Walkoff @5.3um | 0.76(27,c) |
0.67(11) |
| Pockels Coeffs.
(Linear Electro-Optic) |
|
|
| r41T (pm/V) | 4.0 +/-0.2(10) | 4.5 at 1.15um(12) |
| r63T (pm/V) | 3.0 +/-0.1(10) | 3.9 at 1.15um(12) |
| Optical Gyration Coeff. (10-3 deg) |
|
|
| 0.4974um | 3.88(6) | --- |
| 0.5045um | 3.63(13) | --- |
Electrogyration Coeff
 41(10-12)
at 0.498um |
2.03(14) | --- |
| Mechanical Properties |
|
|
| Elastic Compliances, (TPa-1)(10,29) |
|
|
| s11 | 26.2 | 26.6 |
| s12 | -7.7 | -14.9 |
| s13 | -14.5 | -9.1 |
| s33 | 35.9 | 31.4 |
| s44 | 41.5 | 46.1 |
| s66 | 32.5 | 75.2 |
| Young's Modulus, 1/s11E(GPa) | 38.2 | 37.6 |
| Poisson's Ratio, -s12/s11 | 0.29 | 0.56 |
| Elastic Stiffnesses, (GPa)(10,29) |
|
|
| c11 | 87.9 | 89.8 |
| c12 | 58.4 | 65.7 |
| c13 | 59.2 | 45.1 |
| c33 | 75.8 | 58.0 |
| c44 | 24.1 | 21.7 |
| c66 | 30.8 | 13.3 |
| Thermal Properties |
|
|
| Melting point (°C) | 997 | 851(11) |
| Thermal Expansion Coeff.(10-6/°C) |
|
|
| Along c axis | 12.5(15) | 16.8(16) |
| Perpendicular to c axis | -13.2(15) | -7.8(16) |
| Phase transitions | none >RT | none >RT |
| Heat Capacity (J/mole/°C) | 99.8(17) | 97 +/-5 |
| Specific Heat (J/cc/°C) | 1.9 | 1.7 |
 Hmelt
(KJ/mole) |
53.6(18) | 58.6(18) |
| Thermal Conductivity (W/cm/°C)
(nearly isotropic) |
0.015 | 0.011 |
| Electrical Properties |
|
|
| Typical dark Resistivity (ohm-cm) | >1011 | >1010 |
| Relative dielectric constant @25MHz |
|
|
 11S/o |
10(10) | 10.5(7) |
| 33S/o |
14(10) | 12.0(7) |
| Piezoelectric Coefficients, (pC/N) |
|
|
| d14 | + (10) | 9.0(7) |
| d36 | + (10) | 3.7(7) |
| Electromechanical Coupling Factors |
|
|
| k14 | --- | 0.098(7) |
| k36 | --- | 0.040(7) |
|
|
; |
; |
a) Unreferenced data were determined at Cleveland Crystals, Inc.
b) AGS has a high transmission to 8.3um.
c) Calculated from a combination of Cleveland Crystals data, and data referenced herein.
d) The indicies of refraction for AGS(4) were fitted to Sellmeier equations after ref.(24)
e) The indicies of refraction for AGSe(5) were fitted to Sellmeier equations after ref.(27)
f) Calculated value.
g) Recent experimental data, subject to change with crystal development.
h) NOTE: All damage threshold information is provided as a guide only. NO warranty, expressed or implied, is made with regard to damage threshold. Users are encouraged to establish safe operating conditions for their laser system components.
1) Crystal Data, J.D.H. Donnay and H.M. Ondik, Editors, 3rd edition Vol.2(1973) 2) B.Tell and H.M. Kasper,Phys. Rev. B4,4455-9(1971) 3) G.C. Bahr and R.C. Smith, Phys. Status Solidi a13,157-68(1972) 4) G.D. Boyd, H.M. Kasper, and J.H. McFee, IEEE J. Quantum Electron, 7,563-73(1971) 5) G.D. Boyd, H.M. Kasper, J.H. McFee, and F.G. Storz, IEEE J. Quantum Electron, 8,900-908(1972) 6) M.V. Hobden, Acta Cryst. A24, 676-80(1968) 7) H. Horinaka, H. Nozuchi, H. Sonomura, ans T. Miyauchi, Jpn. J. Appl.Phys. 22,546(1979) 8) G.C. Bahr, D.K. Ghosh, and D. Schmitt, Appl. Opt.,22,2492-4(1983) 9) N.P. Barnes R.C. Eckhardt, D.J. Gettemy, and L.B. Edgett, IEEE J. Quantum Electron, 15, 1074-6(1979) 10) Landolt-Boernstein, New Series, K.H. and A.M. Hellwege, Editors, Springer, Berlin Vol.III-11(1979),III-18(1984) 11) R.C. Eckardt, Y.X. Fan, R.L. Beyer, R.K. Route, R.S. Feigelson, and J. van der Laan, Appl. Phys. Lett. 47,786-8(1985) 12) H. Horinaka, H. Sonomura, ans T. Miyauchi, Jpn. J. Appl.Phys. 21,1485-8(1982) 13) W.J. ANderson, P.W. Yu, and Y.S. Park, Opt. Commun.,11,392-5(1974) 14) O.G. Vlokh, A.V. Tsarik, and I.M. Nekrasova, Ukr.Fiz.Zh.(Russ.Ed.)28, 1334-8(1974); Chem. Abstr. 99,148685s(1983) 15) P. Kovaczak and C.B. Staff, J. Cryst. Growth 24/25, 386-9(1974) 16) G.W. Iseler, J. Cryst. Growth 41, 146-50(1977) 17) H.Neumann, G. Kuhl, and W Moller, Cryst. Res. Technol. 20, 1225-9(1985) 18) L.A. Mechkovski, S.A. Alfer, I.V. Bodnar, and A.P. Bologa, Thermochim. Acta 93, 729-32(1985) 19) J.D. Beasley, Applied Optics, to be published in 1994 20) V.P. Zhuze, V.M. Sergeeva, and E.L. Shtrum, Sov. Phyys. Tech. Phys. 3, 1925-38(1958) 21) L.K. Samanta, D.K. Ghosh, and G.C. Bahr, Phys. Status. Solidi, a98, K51-4(1986) 22) I.V. Bidnar and A.I. Lukomskii, Phys. STatus Solidi, a98, K165-9(1986) 23) S.R. Sashital, R.R. Stephens, and J.F. Lotspeich, J. Appl. Phys., 59, 757-60(1986) 24) Y.X. Fan, R.C.Eckardt and R.L. Beyer, Appl. Phys. Lett. 45, 313-15(1984) 25) R.C.Eckardt and R.L. Beyer "Measurement of Nonlinear Optical Componenets by Phase Matched Harmonic Generation", SPIE O-E LASE Proceeding 1991, 119; Also C.L. Marquardt, NRL, private communication 26) "Broadly Tunable Infrared Parametric Oscillation Using AgGaSe2", R.C. Eckardt, Y.X. Fan, R.L. Beyer, C.L. Marquardt, M.E. Storm, and L. Esterowitz, Appl. Phys. Lett. 49, 608-10 (1986) 27) H. Kildal and J.C. Mikkelsen, Opt. Commun. 9, 315-18(1973). Nonlinear data have been summarized and evaluated in ref. 28. 28) "Simplified Characterization of Uniaxial and Biaxial Nonliner Optical Crystals: A plea for Standardization of Nomenclature and Conventions", D. A. Roberts, IEEE J. Quantum Electron, 28, 2057-74(1992) 29) D. Eimerl, J. Marion, E.K. Graham, H.A. Mckinstry, and S. Haussuhl, IEEE J. Quantum Electron. 27, 142-5(1991) 30) N.P. Barnes, D.J. Gettemy, J.R. Hietanen, and R.A. Iannini, Appl. Opt. 28, 5162-8(1989) measurement at 3.39um 31) Laser Science Inc, personal communication, 1983