22 May 2019 Description
LBO crystal — the most excellent nonlinear crystal for Noncritical Phase Matched laser frequency doubling
LBO is one of the excellent non-linear crystals in the ultraviolet band. It has been successfully used in second and third harmonic generation of YLF, YAG, YAP lasers. LBO crystal has wide transmission band, good ultraviolet transmittance, slightly deliquescence, good physical and chemical properties, moderate non-linear optical coefficient, good optical uniformity, high damage threshold, large allowable angle and small walk-off angle. It has been widely used in high average power second harmonic, sum frequency, difference frequency, third harmonic, fourth harmonic and parametric oscillation field.
The greatest advantage of LBO is that temperature tuning can be used to achieve non-critical phase matching (NCPM). When the non-critical phase matching relationship is satisfied in the frequency doubling process, the walk-off angle between the fundamental frequency light and the second harmonic of frequency doubling is 0. At this time, the effective length of LBO crystal can theoretically reach infinity, which can compensate for its small non-linear coefficient. Because its damage threshold is very large, it means that high-power fundamental wave pumping can be realized. Therefore, the conversion efficiency of fundamental frequency light will be greatly improved by using the non-critical phase matching of LBO crystal for the extra-cavity frequency doubling of pulsed laser. The beam quality and stability of frequency light will be greatly improved.
Parameter
Chemical and Physical properties
| Property |
Value |
| Chemical formula |
LiB3O5 |
| Crystal structure |
Orthorhombic, Space group Pna21, Point group mm2 |
| Lattice Parameter |
a=8.4473Å ,b=7.3788Å, c=5.1395Å, Z=2 |
| Mass density |
2.47 g/cm3 |
| Moh hardness |
6 |
| Melting point |
About 834°C |
| Thermal conductivity |
3.5W/m/K |
| Birefringence |
Negative biaxial crystal: 2Vz = 109.2˚ at λ = 0.5321μm |
Coating
| Crystal Dimension/mm |
Length/mm |
Application |
Orientation Theta/Phi deg
|
ARCoatings S1/S2,nm/nm
|
| 5 x 5 |
15 |
THG@1064nm, Type II (e-oe) |
42.2/90 |
1064 + 532 / 355 |
| 15 |
SHG@1064nm, Type I (e-oo) |
90/11.6 |
1064 + 532 / 1064 + 532 |
| 6 x 6 |
0.9 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 1.9 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 2.8 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 3.7 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 10 x 10 |
0.9 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 1.9 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 2.8 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 3.7 |
SHG@1030nm |
90/13.8 |
515 + 1030 / 515 + 1030 |
| 3 x 3 |
10 |
THG@1064nm, Type II (e-oe) |
42.2/90 |
1064 + 532 / 355 |
| 15 |
SHG@1064nm, NCPM I Type |
90/0 |
1064 + 532 / 1064 + 532 |
| 15 |
THG@1064nm, Type II (e-oe) |
42.2/90 |
1064 + 532 / 355 |
| 15 |
SHG@1064nm, Type I (e-oo) |
90/11.6 |
1064 + 532 / 1064 + 532 |
| 20 |
SHG@1064nm, NCPM I Type |
90/0 |
1064 + 532 / 1064 + 532 |
Polishing
| Property |
Value |
| Orientation Tolerence |
< 0.5° |
| Thickness/Diameter Tolerance |
±0.05 mm |
| Surface Flatness |
<λ/8@632 nm |
| Wavefront Distortion |
<λ/4@632 nm |
| Surface Quality |
10/5 |
| Parallel |
30〞 |
| Perpendicular |
15ˊ |
| Clear Aperture |
>90% |
| Chamfer |
<0.2×45° |
Linear Optical Properties
| Property |
Value |
| Transparency Range |
169 – 2600 nm |
| Absorption Coefficient: |
<0.1%/cm at 1064nm;<0.3%/cm at 532nm |
| Refractive Indices |
|
| at 1.0642 mm |
nx = 1.5656, ny = 1.5905, nz=1.6055 |
| at 0.5321 mm |
nx = 1.5785, ny = 1.6065, nz=1.6212 |
| at 0.2660 mm |
nx = 1.5973, ny = 1.6286, nz=1.6444 |
| Sellmeier Equations(λ in μm) |
nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60×10-5λ4 |
| ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.0×10-4λ4 |
| nz2=2.586179+0.013099/(λ2-0.011893)-0.017968λ2-2.26×10-4λ4 |
Nonlinear Optical Properties
| Property |
Value |
| SHG Phase Matchable Range |
551 ~ 2600nm (Type I);790-2150nm (Type II) |
| NLO coefficients |
deff(I)=d32cosΦ (Type I in XY plane) |
| deff(I)=d31cos2θ+d32sin2θ (Type I in XZ plane) |
| deff(II)=d31cosθ (Type II in YZ plane) |
| deff(II)=d31cos2θ+d32sin2θ (Type II in XZ plane) |
| Non-vanished NLO susceptibilities |
d31=1.05 ± 0.09 pm/V |
| d32=-0.98 ± 0.09 pm/V |
| d33= 0.05 ± 0.006 pm/V |
| Therm-Optic Coefficients(°C,λ in μm) |
dnx/dT=-9.3X10-6 |
| dny/dT=-13.6X10-6 |
| dnz/dT=(-6.3-2.1λ)X10-6 |
| Angle Acceptance |
6.54mrad-cm (Φ, Type I,1064 SHG)15.27mrad-cm (q, Type II,1064 SHG) |
Linear Thermal Expansion Coefficient
| T [K] |
αt×106[ K-1],||X |
αt×106[K-1 ],||Y |
αt×106[ K-1],||Z |
| 273 |
107.1 |
-95.4 |
33.7 |
| 323 |
108.2 |
-88 |
33.6 |
| 373 |
108.3 |
-80.9 |
33.2 |
| 423 |
107.3 |
-74.0 |
32.6 |
| 473 |
105.3 |
-67.3 |
31.7 |
| 523 |
102.3 |
-60.7 |
30.5 |
| 573 |
98.2 |
-54.4 |
29.1 |
| 673 |
87.0 |
-42.3 |
25.5 |
| 723 |
79.8 |
-36.5 |
23.3 |
| 773 |
71.6 |
-30.9 |
20.9 |
| 873 |
52.1 |
-20.3 |
15.3 |
| 923 |
40.8 |
-15.3 |
12.1 |
| 973 |
28.5 |
-10.6 |
8.7 |
| 1023 |
15.1 |
-5.9 |
5.0 |
| 1073 |
0.8 |
1.5 |
1.1 |
Experimental Values of Refractive Indices
| λ[µm] |
nX |
nY |
nZ |
| 0.2537 |
1.6335 |
1.6582 |
1.6792 |
| 0.2894 |
1.6209 |
1.6467 |
1.6681 |
| 0.2968 |
1.6182 |
1.6450 |
1.6674 |
| 0.3125 |
1.6097 |
1.6415 |
1.6588 |
| 0.3341 |
1.6043 |
1.6346 |
1.6509 |
| 0.3650 |
1.59523 |
1.62518 |
1.64025 |
| 0.4000 |
1.58995 |
1.61918 |
|
| 0.4047 |
1.5907 |
1.6216 |
1.6353 |
| 0.4358 |
1.5859 |
1.6148 |
1.6297 |
| 0.4500 |
1.58449 |
1.61301 |
1.62793 |
| 0.4861 |
1.5817 |
1.6099 |
1.6248 |
| 0.5000 |
1.58059 |
1.60862 |
1.62348 |
| 0.5250 |
1.57906 |
1.60686 |
|
| 0.5321 |
1.57868 |
1.60642 |
1.62122 |
| 0.5461 |
1.5780 |
1.6057 |
1.6206 |
| 0.5500 |
1.57772 |
1.60535 |
1.62014 |
| 0.5780 |
1.5765 |
1.6039 |
1.6187 |
| 0.5893 |
1.5760 |
1.6035 |
1.6183 |
| 0.6000 |
1.57541 |
1.60276 |
1.61753 |
| 0.6328 |
1.5742 |
1.6014 |
1.6163 |
| 0.6563 |
1.5734 |
1.6006 |
1.6154 |
| 0.7000 |
|
1.59893 |
1.61363 |
| 0.8000 |
1.56959 |
1.59615 |
1.61078 |
| 0.9000 |
1.56764 |
1.59386 |
1.60843 |
| 1.0000 |
1.56586 |
1.59187 |
1.60637 |
| 1.0642 |
1.56487 |
1.59072 |
1.60515 |
| 1.1000 |
1.56432 |
1.59005 |
1.60449 |
Experimental Values of Phase-matching Angle (T =293K)
| Interacting wavelengths[μm] |
Φexp [deg] |
θexp [deg] |
|
XY plane θ=90°
SHG, o+o ⇒ e
|
|
|
| 1.908⇒0.954 |
23.8 |
|
| 1.5⇒0.75 |
7 |
|
| 1.0796⇒0.5398 |
10.6/10.7 |
|
| 1.0642⇒0.5321 |
11.3/11.4/11.6/11.8 |
|
| 0.946⇒0.473 |
19.4/19.5 |
|
| 0.930⇒0.465 |
21.3 |
|
| 0.896⇒0.448 |
23.25 |
|
| 0.88⇒0.44 |
24.53 |
|
| 0.850⇒0.425 |
27 |
|
| 0.84⇒0.42 |
27.92 |
|
| 0.836⇒0.418 |
28.3 |
|
| 0.80⇒0.40 |
31.70 |
|
| 0.794⇒0.397 |
32.3 |
|
| 0.786⇒0.393 |
33 |
|
| 0.78⇒0.39 |
33.70 |
|
| 0.7735⇒0.38675 |
34.4 |
|
| 0.75⇒0.375 |
37.13/37 |
|
| 0.746⇒0.373 |
37.5 |
|
| 0.7094⇒0.3547 |
41.8/41.9/42/43.5 |
|
| 0.63⇒0.315 |
55.6 |
|
| 0.555⇒0.2775 |
86 |
|
| 0.554⇒0.277 |
90 |
|
| SFG, o+o ⇒ e |
|
|
| 1.3414+0.6707⇒0.44713 |
20 |
|
| 1.0642+0.5321⇒0.35473 |
37/37.1/37.2 |
|
| 1.053+0.5265⇒0.351 |
38.2 |
|
| 1.0642+0.35473⇒0.26605 |
60.7/61 |
|
| 0.86+0.43⇒0.2867 |
61 |
|
| 1.3188+0.26605⇒0.22139 |
70.2 |
|
| 0.21284+2.35524⇒0.1952 |
50.3 |
|
| 0.21284+1.90007⇒0.1914 |
63.8 |
|
| 0.21284+1.58910⇒0.18774 |
88 |
|
|
YZ plane, Φ=90◦
SHG, o+e ⇒ o
|
|
|
| 1.908⇒0.954 |
|
46.2 |
| 1.5⇒0.75 |
|
14.7 |
| 1.0796⇒0.5398 |
|
19.2 |
| 1.0642⇒0.5321 |
|
19.9/20.5/20.6/21.0 |
| SFG, o+e ⇒ o |
|
|
| 1.0641+0.53205⇒0.3547 |
|
42/42.7 |
| 1.0642+0.5321⇒0.35473 |
|
42.2/42.5/43.2 |
|
XZ plane, Φ=0◦, θ＜VZ
SHG, e+o ⇒ e
|
|
|
| 1.3414⇒0.6707 |
|
3.6/4.2/5.0 |
| 1.3188⇒0.6594 |
|
5.2 |
| 1.3⇒0.65 |
|
5.4 |
|
XZ plane, Φ=0◦, θ＞VZ
SHG, e+e ⇒ o
|
|
|
| 1.3414⇒0.6707 |
|
86.1/86.3/86.6 |
| 1.3188⇒0.6594 |
|
86.0 |
| 1.3⇒0.65 |
|
86.1 |
| 1.24⇒0.62 |
|
86 |
Experimental Values of Non-critical Phase Matching (NCPM) Temperature
|
Interacting wavelengths[μm]
|
T[℃]
|
|
along X axis
SHG, typeⅠ
|
|
|
1.547⇒0.7735
|
117
|
|
1.46⇒0.73
|
50
|
|
1.252⇒0.626
|
3.5
|
|
1.25⇒0.625
|
-2.9
|
|
1.215⇒0.6075
|
21
|
|
1.211⇒0.6055
|
20
|
|
1.206⇒0.603
|
24
|
|
1.2⇒0.6
|
24.3
|
|
1.15⇒0.575
|
61.1
|
|
1.135⇒0.5675
|
77.4
|
|
1.11⇒0.555
|
108.2
|
|
1.0796⇒0.5398
|
112
|
|
1.0642⇒0.5321
|
148/148.5/149/149.5/151
|
|
1.047⇒0.5235
|
166.5/167/172/175/176.5/180
|
|
1.025⇒0.5125
|
190.3
|
|
SFG, typeⅠ
|
|
|
1.908+1.0642⇒0.6832
|
81
|
|
1.444+1.08⇒0.6179
|
23
|
|
1.135+1.0642⇒0.5491
|
112
|
|
1.547+0.7735⇒0.5157
|
141
|
|
DFG, typeⅠ
|
|
|
0.532-0.8⇒1.588
|
135
|
|
along Z axis
SHG, type II
|
|
|
1.342⇒0.671
|
35
|
|
1.3⇒0.65
|
46
|
Experimental Values of Internal Angular, Temperature, and Spectral Bandwidths
| Interacting wavelengths[μm] |
T[℃] |
Δφint [deg] |
Δθint [deg] |
ΔT[℃] |
| along X axis |
|
|
|
|
| SHG, type I |
|
|
|
|
| 1.46⇒0.73 |
50 |
|
|
6 |
| 1.252⇒0.626 |
3.5 |
|
|
9 |
| 1.206⇒0.603 |
24 |
|
|
13 |
| 1.135⇒0.5675 |
77.4 |
|
|
4.7 |
| 1.0642⇒0.5321 |
148 |
3.54 |
2.57 |
3.9 |
| 148.5 |
|
|
2.7 |
| 149 |
2.3 |
1.9 |
4 |
| 149.5 |
|
|
4.1 |
| 151 |
2.1 |
2.1 |
2.9 |
| 1.047⇒0.5235 |
175 |
|
|
3.5 |
| SFG, type I |
|
|
|
|
| 1.908+1.0642⇒0.6832 |
81 |
|
|
7.4 |
| 1.444+1.08⇒0.6179 |
23 |
4.2 |
3 |
|
| 1.135+1.0642⇒0.5491 |
112 |
|
|
5 |
| DFG, type I |
|
|
|
|
| 0.532-0.8⇒1.588 |
135 |
|
|
3.8 |
Experimental Values of Internal Angular, Temperature, and Spectral Bandwidths
| Interacting wavelengths[μm] |
Φpm[deg] |
θpm[deg] |
Δφint[deg] |
Δθint[deg] |
ΔT[℃] |
Δν[cm-1] |
| XY plane, θ =90(T=293K) |
|
|
|
|
|
|
| SHG, o+o ⇒ e |
|
|
|
|
|
|
| 1.0796⇒0.5398 |
10.7 |
|
0.31 |
|
|
|
| 1.0642⇒0.5321 |
10.8 |
|
0.27 |
2.63 |
|
|
| 11.4 |
|
0.24 |
1.79 |
|
|
| 11.6 |
|
|
|
5.8 |
|
| |
|
0.34 |
2.64 |
6.7 |
8.8 |
| 0.886⇒0.443 |
24.1 |
|
|
|
7.8 |
15.9 |
| 0.870⇒0.435 |
25.4 |
|
0.12 |
|
|
141 |
| 0.78⇒0.39 |
33.7 |
|
0.08 |
|
|
194 |
| 0.7605⇒0.38025 |
35.9 |
|
|
|
15.3 |
10.5 |
| 0.715⇒0.3575 |
41 |
|
0.06 |
|
|
|
| SFG, o+o ⇒ e |
|
|
|
|
|
|
| 1.0642+0.3547⇒0.2661 |
60.7 |
|
|
|
3.8 |
|
| YZ plane, φ =90(T=293K) |
|
|
|
|
|
|
| SHG, o+e ⇒ o |
|
|
|
|
|
|
| 1.0642⇒0.5321 |
|
20.6 |
3.2 |
0.77 |
|
|
| |
|
3 |
0.81 |
|
11.5 |
| SFG, o+e ⇒ o |
|
|
|
|
|
|
| 1.0641+0.53205⇒0.3547 |
|
42 |
0.79 |
0.16 |
6 |
|
| 1.0642+0.5321⇒0.35473 |
|
42.2 |
|
0.18 |
|
|
| |
41 |
3.07 |
0.18 |
|
|
Calculated Values of Inverse Group-velocity Mismatch for SHG Process in LBO
| Interacting wavelengths[μm] |
Φpm[deg] |
θpm[deg] |
β[fs/mm] |
| XY plane, θ =90◦ |
|
|
|
| SHG, o+o ⇒ e |
|
|
|
| 1.2⇒0.6 |
2.36 |
|
18 |
| 1.1⇒0.55 |
9.37 |
|
37 |
| 1.0⇒0.5 |
15.74 |
|
59 |
| 0.9⇒0.45 |
22.94 |
|
86 |
| 0.8⇒0.4 |
31.69 |
|
123 |
| 0.7⇒0.35 |
43.38 |
|
175 |
| 0.6⇒0.3 |
62.63 |
|
257 |
| YZ plane, φ =90◦ |
|
|
|
| SHG, o+e ⇒ o |
|
|
|
| 1.1⇒0.55 |
|
15.98 |
82 |
| 1.0⇒0.5 |
|
28.96 |
106 |
| 0.9⇒0.45 |
|
45.36 |
139 |
| 0.8⇒0.4 |
|
76.88 |
186 |
Laser-induced Surface-damage Threshold
| λ[µm] |
τp [ns] |
Ithr [GW/cm2] |
Note |
| 0.2661 |
12 |
>0.04 |
|
| 0.308 |
17 |
>0.05 |
|
| 0.0003 |
47,000 |
sharp focusing |
| 0.3547 |
18 |
>0.18 |
10Hz |
| 8 |
>0.1 |
|
| 7 |
>0.14 |
|
| 0.03 |
>9.4 |
10Hz |
| 0.015 |
>2.8 |
|
| 0.018 |
>5 |
|
| 0.025 |
>6 |
10Hz |
| 0.5145 |
CW |
>0.00003 |
|
| 0.5235 |
0.055 |
>1.1 |
500Hz |
| 0.5321 |
CW |
>0.0004 |
|
| 60 |
>0.07 |
900Hz |
| 10 |
>0.22 |
|
| 0.1 |
>4.5 |
500Hz |
| 0.035 |
>3.1 |
|
| 0.015 |
>4.4 |
|
| 0.592 |
0.0005 |
>50 |
1kHz |
| 0.605 |
0.0002 |
>25 |
|
| 0.616 |
0.0004 |
31,000 |
sharp focusing |
| 0.652 |
0.02 |
>0.81 |
|
| 0.7–0.9 |
10 |
>0.03 |
10Hz |
| 0.71–0.87 |
25 |
1.1–1.4 |
25Hz |
| 0.72–0.85 |
0.001 |
>8 |
|
| 0.77–0.83 |
0.00005 |
>22 |
80MHz |
| 1.0642 |
CW |
>0.001 |
|
| 60 |
>0.06 |
1333Hz |
| 18 |
>0.6 |
10Hz |
| 9 |
>0.9 |
10Hz |
| 8 |
>0.5 |
|
| 1.3 |
19 |
|
| 1.1 |
45 |
bulk damage |
| 0.1 |
25 |
|
| 0.035 |
>4.8 |
|
| 0.025 |
>3.3 |
10Hz |
| 1.0796 |
5 |
20 |
1–25Hz |
| 0.04 |
30 |
|
Temperature derivative of refractive indices
for spectral range 0.4–1.0µm and temperature range 293–338K (λ in µm):
dnX/dT=-1.8×10-6K-1
dny/dT=-13.6×10-6K-1
dnz/dT=-(6.3+2.1λ)×10-6K-1
for spectral range 0.4–1.0 µm and temperature range 293–383K (λ in µm):
dnX/dT=-(3.76λ-2.3)×10-6K-1
dny/dT=-(19.40-6.01λ)×10-6K-1
dnz/dT=-(9.70-1.50λ)×10-6K-1
for λ =0.6328µm and temperature range 293–473K (λ in µm, T in K):
dnX/dT=[0.20342-1.9697×10-2 (T-273)-1.4415×10-5(T-273)2]×10-6K-1
dny/dT=-[10.748+7.1034×10-2 (T-273) +5.7387×10-5(T-273)2]×10-6K-1
dnz/dT=-[0.85998+1.5476×10-1 (T-273) -9.4675×10-4(T-273)2+2.2375×10-6(T-273)3]×10-6K-1
Other Parameters
| Specific Heat Capacity cp at P =0.101325 MPa |
| T [K] |
cp[J/kgK] |
|
|
| 298 |
1060 |
|
|
| Linear Absorption Coefficient α |
| λ[µm] |
α [cm-1] |
|
|
| 0.35–0.36 |
0.0031 |
|
|
| 1.0642 |
0.00035 |
|
|
| Two-photon Absorption Coefficient β |
| λ[µm] |
τp[ns] |
β×1011[cm/W] |
Note |
| 0.211 |
0.0009 |
103±36 |
θ =90°, Φ=30° |
| 0.264 |
0.0008 |
15±5 |
θ =90°, Φ=30° |
| Nonlinear Refractive Index γ |
| λ[µm] |
γ×1015[cm2/W] |
Note |
|
|
0.78
|
0.26±0.03 |
[100] direction |
|
| 0.19±0.03 |
[010] direction |
|
| 0.85 |
0 .19±0.04 |
|
|
Features
-
Low sensitivity to moisture
-
Dispertive angle is small
-
High optical homogeneity
-
The range of tunable wavelengths is large
-
The region of transparency is wide
-
Damage threshold is high
-
Wide acceptance angle
Applications
Material Processing
Optical Communication
Holography
Medical Applications
OPA(Optical parametric amplifiers) and OPO(oscillators)
SHG(Frequency harmonic doubling) and THG(Tripling harmonic doubling)
Diode laser pumped Nd: YLF laser and Nd:YAG laser. Alexandrite, Ti:Sapphire, Dye Lasers, Ultrashort Pulse Lasers |
