22 May 2019 Description
ZnGeP2（Zinc germanium phosphide）crystal has many good properties and is an mid-IR nonlinear crystal. The nonlinear susceptibility of ZnGeP2 (ZGP) crystal is approximately 160 times large (d36~75 pm/V) as KDP,.ZGP shows good optical transparency over the 0.74–12 mm and relatively high laser damage threshold, and is therefore well suited for producing near infrared tunable laser. ZGP is a very hopeful material for mid-infrared devices such as SHG, SFG, OPO, and OPG/OPA.
Parameter
Chemical and Physical properties
| Property |
Value |
| Chemical Formula |
ZnGeP2 |
| Crystal Structure |
Tetragonal,`42m |
| Lattice Parameter |
a=b=5.467Å, c=12.736Å |
| Mass Density |
4.16 g/cm3 |
| Moh Hardness |
5.5 |
| Melting Point |
About 1040°C |
| Thermal Conductivity |
180 W/m/K |
| Thermal Expansion Coefficient |
β‖,5×10-6/K; β⊥,7.8×10-6/K |
| Birefringence |
positive uniaxial |
Linear Optical Properties
| Property |
Value |
| Transparency Range |
0.74 – 12 um |
| Absorption Coefficient |
α |
| Refractive Indices |
| @ 2.05 um |
no = 3.1478, ne = 3.1891 |
| @ 2.79 um |
no = 3.1333, ne = 3.1744 |
| @ 5.30 um |
no = 3.1136, ne = 3.1547 |
| @ 10.6 um |
no = 3.0729, ne = 3.1143 |
| Sellmeier Equations(λ in μm) |
no2(λ) = 4.64467+5.10087/(λ2-0.13656)+4.27777λ2/(λ2-1653.89) |
| ne2(λ) = 4.71539+5.26358/(λ2-0.14386)+2.37310λ2/(λ2-1000.82) |
Nonlinear Optical Properties
| Property |
Value |
| SHG Phase Matchable Range |
3177 ∼ 10357nm (Type I) |
| NLO coefficients |
d36=75 ± 8 pm/V |
| Type Ⅰ deeo=d36 sin2θcos2φ |
| Type Ⅱ doeo=deoo=d36 sinθsin2φ |
| Damage Threshold |
|
| at 2.79 um |
30 GW/cm2 (150 ps) |
| at 10.6 um |
1 GW/cm2 (2 ns) |
Linear Absorption Coefficient
| λ[µm] |
α [cm-1] |
Note |
| 1.064 |
1.52 |
|
| 1.06 |
best crystals |
| 1.9 |
0.8–0.95 |
|
| 2 |
0.15 |
o-wave, best crystals |
| 0.16 |
|
| 2.05 |
0.35 |
|
| 0.26 |
o-wave |
| 0.23 |
|
| 0.2 |
o-wave, after annealing |
| <0.1 |
best crystals |
| 0.09 |
best crystals |
| 0.02–0.04 |
after annealing and radiation processing |
| 2.08 |
0.62 |
o-wave, mean value |
| 1.2 |
e-wave, mean value |
| 2.15 |
0.6 |
|
| 0.09–0.25 |
typical crystals, o-wave |
| 0.03 |
best crystals, o-wave |
| 2.39 |
0.55 |
|
| 2.5 |
0.11 |
o-wave, as-grown crystals |
| 2.5–8 |
<0.1 |
|
| 2.5–8.3 |
<0.2 |
|
| 2.5–8.5 |
<0.1 |
|
| 2.73 |
0.03 |
|
| 2.75 |
0.3 |
|
| 2.79 |
0.06 |
|
| 2.8 |
0.01 |
best crystals, o-wave |
| 2.8–8.3 |
<0.1 |
|
| 3–8 |
0.005–0.15 |
|
| <0.1 |
|
| <0.01 |
|
| 3.15 |
0.17 |
|
| 3.5–3.9 |
0.41 |
o-wave, SFG direction |
| 3.5 |
0.4 |
|
| 3.8 |
0.1–0.18 |
|
| 3.9–4.5 |
0.1 |
|
| 4–8.5 |
<0.05 |
|
| 4.5–8 |
0.03 |
best samples |
| 4.65 |
0.4 |
|
| 0.1–0.2 |
|
| 0.01–0.05 |
SHG direction |
| 4.78 |
<0.055 |
|
| 0.16 |
|
| 5.3–6.1 |
0.32 |
e-wave, SFG direction |
| 5.5–6.3 |
0.1 |
|
| 7.8 |
0.15 |
|
| 8.24 |
0.02 |
|
| 8.3 |
0.45 |
|
| 8.3–9.5 |
<0.3 |
|
| 9 |
0.9 |
|
| 9.2 |
0.51 |
|
| 9.28 |
0.4 |
|
| 9.3 |
0.8 |
|
| 0.7 |
SHG direction |
| 0.4–0.5 |
|
| 0.48 |
e-wave |
| 9.5 |
0.39 |
e-wave |
| 9.55 |
0.26 |
SHG direction |
| 0.56 |
|
| 9.6 |
0.33 |
|
| 9.7 |
0.33 |
e-wave |
| 10 |
0.45 |
|
| 10.3 |
0.42 |
|
| 10.4 |
0.6 |
|
| 10.6 |
0.9 |
|
| 0.83 |
e-wave, SFG direction |
| 0.65 |
|
| 10.7 |
0.88 |
e-wave |
| 11.1 |
1.2 |
|
Experimental Values of Refractive Indices
| λ[µm] |
no |
ne |
λ[µm] |
no |
ne |
| 0.64 |
3.5052 |
3.5802 |
3.40 |
3.1263 |
3.1647 |
| 0.66 |
3.4756 |
3.5467 |
3.60 |
3.1257 |
3.1632 |
| 0.68 |
3.4477 |
3.5160 |
3.80 |
3.1237 |
3.1616 |
| 0.70 |
3.4233 |
3.4885 |
4.00 |
3.1223 |
3.1608 |
| 0.75 |
3.3730 |
3.4324 |
4.20 |
3.1209 |
3.1595 |
| 0.80 |
0.80 |
3.3915 |
4.50 |
3.1186 |
3.1561 |
| 0.85 |
3.3063 |
3.3593 |
4.70 |
3.1174 |
3.1549 |
| 0.90 |
3.2830 |
3.3336 |
5.00 |
3.1149 |
3.1533 |
| 0.95 |
3.2638 |
3.3124 |
5.50 |
3.1131 |
3.1518 |
| 1.00 |
3.2478 |
3.2954 |
6.00 |
3.1101 |
3.1480 |
| 1.10 |
3.2232 |
3.2688 |
6.50 |
3.1057 |
3.1445 |
| 1.20 |
3.2054 |
3.2493 |
7.00 |
3.1040 |
3.1420 |
| 1.30 |
3.1924 |
3.2346 |
7.50 |
3.0994 |
3.1378 |
| 1.40 |
3.1820 |
3.2244 |
8.00 |
3.0961 |
3.1350 |
| 1.60 |
3.1666 |
3.2077 |
8.50 |
3.0919 |
3.1311 |
| 1.80 |
3.1562 |
3.1965 |
9.00 |
3.0880 |
3.1272 |
| 2.00 |
3.1490 |
3.1889 |
9.50 |
3.0836 |
3.1231 |
| 2.20 |
3.1433 |
3.1829 |
3.1829 |
3.0788 |
3.1183 |
| 2.40 |
3.1388 |
3.1780 |
10.50 |
3.0738 |
3.1137 |
| 2.60 |
3.1357 |
3.1745 |
11.00 |
3.0689 |
3.1087 |
| 3.00 |
3.1304 |
3.1693 |
12.00 |
3.0552 |
3.0949 |
| 3.20 |
3.1284 |
3.1671 |
|
|
|
Experimental Values of Phase-matching Angle (T =293K)
| Interacting wavelengths[μm] |
θexp [deg] |
| SHG, e+e⇒o |
|
| 3.9278⇒1.9639 |
57.8±0.3 |
| 4.34⇒2.17 |
55.8±0.2 |
| 4.64⇒2.32 |
47.5 |
| 4.775⇒2.3875 |
49.2 |
| 5.2955⇒2.64775 |
46.8 |
| 9.2⇒4.6 |
63.8 |
| 9.3054⇒4.6527 |
61.3/63/64 |
| 9.5⇒4.75 |
62.1/66.8 |
| 9.5524⇒4.7762 |
65.3 |
| 9.6036⇒4.8018 |
64.9/65.8 |
| 10.2⇒5.1 |
72 |
| 10.3035⇒5.15175 |
74.3/74.5 |
| 10.5514⇒5.2757 |
79.2 |
| 10.5910⇒5.2955 |
80.1 |
| SFG, e+e ⇒ o |
|
| 10.668+4.34⇒3.085 |
54.3±0.2 |
| 10.5910+5.2955⇒3.53033 |
52.1 |
| 10.5910+3.53033⇒2.64775 |
48.4 |
| 9.74+4.2039⇒2.9365 |
49.6 |
| 5.2955+3.53033⇒2.1182 |
51.7 |
| SFG, o+e ⇒ o |
|
| 6.74+5.2036⇒2.9365 |
76 |
| 6.45+5.3908⇒2.9365 |
79.2 |
| 6.25+5.5389⇒2.9365 |
84 |
| 6.15+5.6199⇒2.9365 |
85.5 |
| 6.29+5.0173⇒2.791 |
76 |
| 6.19+5.0828⇒2.791 |
77.6 |
| 6.06+5.1739⇒2.791 |
80.5 |
| 6.015+5.207⇒2.791 |
84 |
| 5.95+5.2569⇒2.791 |
83.4 |
| 5.90+5.2965⇒2.791 |
87 |
| 10.5910+1.0642⇒0.96703 |
84 |
Experimental Values of Internal Angular Bandwidth
| Interacting wavelengths[μm] |
Δθint [deg] |
| SHG, e+e ⇒ o |
|
| 3.8⇒1.9 |
1.33 |
| 4.34⇒2.17 |
1.05 |
| 5.3⇒2.65 |
0.69 |
| 7.8⇒3.9 |
0.5 |
| 9.3⇒4.65 |
0.74–0.80 |
| 0.83 |
| 1.15 |
| 9.55⇒4.775 |
0.89 |
| 9.6⇒4.8 |
0.8 |
| 10.2⇒5.1 |
1.35 |
| 10.3⇒5.15 |
1.2 |
| SFG, e+e ⇒ o |
|
| 10.668+4.34⇒3.085 |
1.23 |
| SFG, o+e ⇒ o |
|
| 10.6+1.064⇒0.967 |
0.55 |
Temperature Variation of Phase-matching Angle
| Interacting wavelengths [μm] |
dθpm/dT [deg/K] |
| SHG, e+e ⇒ o |
|
| 9.2⇒4.6 |
0.014 |
| 10.3⇒5.15 |
0.072 |
| 10.6⇒5.3 |
0.107 |
| SFG, o+e ⇒ o |
|
| 10.6+1.0642⇒0.9671 |
0.007 |
Laser-induced Surface-damage Threshold
| λ[µm] |
τp [ns] |
Ithr[GW/cm2] |
Note |
| 1.0642 |
30 |
>0.003 |
12.5Hz |
| 10 |
0.003 |
|
| 1.3 |
0.00013 |
>150 |
1kHz |
| 1.66 |
0.00013 |
>100 |
1kHz |
| 2.05 |
30 |
0.013–0.016 |
5kHz |
| 10 |
>0.074 |
10kHz |
| 2.79 |
50 |
>0.014 |
10Hz |
| |
0.018 |
10Hz |
| 0.15 |
30 |
|
| 0.1 |
35 |
1Hz |
| 2.8 |
70 |
0.056 |
1Hz, uncoated sample |
| |
1Hz, coated samples |
| 0.08 |
|
| 2.94 |
0.11 |
30 |
|
| 5.3–6.1 |
CW |
>0.00001 |
|
| 0.00025 |
|
| 7.8 |
5000 |
10 |
|
| 9.2–10.8 |
CW |
>0.00008 |
|
| 9.28 |
2 |
1.25 |
|
| 9.3 |
100 |
0.012 |
100Hz |
| 50 |
>0.06 |
1Hz |
| 9.3–10.6 |
125 |
0.025 |
20Hz |
| |
0.03–0.04 |
2Hz |
| 9.55 |
220 |
0.078 |
|
| 30 |
0.14 |
SHG direction |
| 10.2–10.8 |
CW |
>0.000001 |
|
| 100,000–10,000,000 |
0.06 |
1500Hz |
| 10.6 |
CW |
>0.00000001 |
|
| |
0.0002 |
|
Experimental Values of Spectral Bandwidth and Temperature Bandwidth
| Experimental Values of Spectral Bandwidth |
| Interacting wavelengths[μm] |
Δν[cm-1] |
|
| SHG, e+e ⇒ o |
|
|
| 4.34⇒2.17 |
7.9 |
|
| 10.2⇒5.1 |
4.9 |
|
| Experimental Values of Temperature Bandwidth |
| Interacting wavelengths[μm] |
θexp[deg] |
ΔT[℃] |
| SHG, e+e ⇒ o |
|
|
| 10.5910⇒5.2955 |
80.1 |
44 |
| 10.3035⇒5.15175 |
74.5 |
45 |
| 10.2⇒5.1 |
72 |
50 |
| 9.6036⇒4.8018 |
65.8 |
48 |
| SFG, o+e ⇒ o |
|
|
| 10.5910+1.0642⇒0.96703 |
84 |
81.9 |
Other Parameters
| Linear Thermal Expansion Coefficient αt |
| ΔT [K] |
αt×106[K-1], ||c |
αt×106[K-1], ⊥c |
| 293–573 |
15.9 |
17.5 |
| 573–873 |
8.08 |
9.1 |
| Thermal Conductivity Coefficient κ： |
| T [K] |
κ[W/mK], ||c |
κ[W/mK], ⊥c |
| 293 |
36 |
35 |
| Two-photon Absorption Coefficient β |
| λ[μm] |
τp[ns] |
β×1011 |
| 1.3 |
0.00013 |
25 |
| Linear Electrooptic Coefficients Measured at High Frequencies(well above the acoustic resonances of ZnGeP2 crystal,i.e.,for the “clamped” crystal)at Room Temperature: |
| λ[µm] |
r41S[pm/V] |
r63S[pm/V] |
| 3.3913 |
1.6 |
-0.8 |
Spectrums
   
Features
-
Nonlinear coefficient is large
-
The region of transmission is from 0.74 um to 12um
-
High relative damage threshold
-
High thermal conductivity
-
The region of transparency is wide
-
Phase matching over a broad spectral region
Applications
-
Producing coherent radiation in sub-millimeter-range from 70.0 μm to 1000 μm - terahertz range
-
Combining frequencies of CO2- and CO-lasers radiation or other lasers that working in the transparency region of ZGP
-
SHG of CO-laser
-
Second, third, and fourth harmonic generation of CO2 laser
-
OPO(Optical parametric generation) with pumping at wavelengths of 2.05-2.94 μm and possibility to generate effectively 3-10 μm ranges
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