LBO crystal is an excellent nonlinear optical crystal. For frequency doubling (SHG), tripling (THG) of Nd:YAG, Nd:YLF, Nd:YVO4 lasers, it is one of the most useful nonlinear optical materials in ultraviolet and visible laser applications.
Advantages:
1. Broad transparency range from 160nm to 2.6mm(SHG range from 0.55m to 2.6mm)
2. Relatively large effective SHG coefficient (about three times larger than that of KDP)
3. High damage threshold (18.9 GW/cm2 for a 1.3ns laser at 1.054mm)
4. Type I and type II non-critical phase-matching (NCPM) over a wide wavelength range
5. Wide acceptance angle and small walk-off
Applications:
6. More than 480 mW output at 395 nm is generated by frequency-doubling a 2W mode-locked Ti:Sapphire laser (<2ps, 82MHz). The wavelength range of 700~900 nm is covered by a 5x3x8 mm3 LBO crystal
7. The frequency-doubling of a Spectra-Physics TFR diode pumped Nd:YLF laser (>500mJ@1047 nm, < 7 ns, 0-10 KHz) reaches over 40% conversion efficiency in a 9 mm LBO.
8. The VUV output at 187.7 nm is obtained by sum-frequency generation
9. 2mJ/pulse diffraction-limited beam at 355 nm is obtained by intracavity tripling a Q-switched Nd:YAG laser
Chemical and Structural properties of LBO:
| Crystal Structure | Orthorhombic, Space group Pna21, Point group mm2 |
| Lattice Parameter | a=8.4473Å, b=7.3788Å , c=5.1395Å , Z=2 |
| Melting Point | About 834℃ |
| Mohs Hardness | 6 |
| Density | 2.47 g/cm3 |
| Thermal Conductivity | 3.5W/m/K |
| Thermal Expansion Coefficient | ax=10.8x10-5/K, ay= -8.8x10-5/K, az=3.4x10-5/K |
Optical and Nonlinear Optical Properties of LBO:
| 160-2600nm | |
| SHG Phase Matchable Range | 551 ~ 2600nm (Type I) , 790~2150nm (Type II) |
| Therm-optic Coefficient(°C) | dnx/dT=-9.3X10-6 , dny/dT=-13.6X10-6, dnz/dT=(-6.3-2.1λ)X10-6 |
| Absorption Coefficient | <0.1%/cm at 1064nm , <0.3%/cm at 532nm |
| Angle Acceptance | 6.54mrad-cm (φ,Type I,1064 SHG), 15.27mrad-cm (q,Type II,1064 SHG) |
| Temperature Acceptance | 4.7°C-cm (Type I, 1064 SHG) , 7.5°C-cm (Type II,1064 SHG) |
| Spectral Acceptance | 1.0nm-cm (Type I, 1064 SHG) , 1.3nm-cm (Type II,1064 SHG) |
| Walk-off Angle | 0.60° (Type I 1064 SHG) , 0.12° (Type II 1064 SHG) |
| 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 |
| Sellmeier Equations (λ in μm) | nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60x10-5λ4 ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.0x10-4λ4 nz2=2.586179+0.013099/(λ2-0.011893)-0.017968λ2-2.26x10-4λ4 |
| Sellmeier Equations (λ in μm) | nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60x10-5λ4 ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.0x10-4λ4 nz2=2.586179+0.013099/(λ2-0.011893)-0.017968λ2-2.26x10-4λ4 |
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