LBO

LBO


LBO (Lithium Triborate, LiB3O5) crystal is an excellent nonlinear 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.

Advantage  

Broad transparency range from 160nm to 2600nm
High optical homogeneity (δn≈10-6/cm) and being free of inclusion;
Relatively large effective SHG coefficient (about three times that of KDP);
Wide acceptance angle and small walk-off;
Type I and type II non-critical phase matching (NCPM) in a wide wavelength range;
Spectral NCPM near 1300nm.
High damage threshold(18.9GW/cm 2 for a 1.3ns laser at 1053nm);                   
LBO has the highest damage threshold in all the commonly-used inorganic NLO crystals. Therefore, it is the best candidate for high average power SHG and other nonlinear optical processes.
 

 

 Basic Properties

Items Specifications
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°C
Mohs Hardness     6
Density  2.47 g/cm3
Thermal Conductivity    3.5W/m/K
Thermal Expansion Coefficient αx=10.8x10-5/K, aαy= -8.8x10-5/K, aαz=3.4x10-5/K
Transparency Range 160-2600nm
SHG Phase Matchable Range 551 ~ 2600nm  (Type I)      790-2150nm (Type II)
Therm-optic Coefficient
(°C, λ in μm)
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    (θ, 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 Coefficient deff(I)=d32cosf              (Type I  in XY plane)
deff(I)=d31cos2q+d32sin2q    (Type I  in XZ plane)
deff(II)=d31cosq              (Type II in YZ plane)
deff(II)=d31cos2q+d32sin2q    (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)      
n2x =2.454140+0.011249/(λ2 -0.011350)-0.014591λ2 -6.60´10-5 λ2 ( l in mm, T=20 oC)
n2y =2.539070+0.012711/(λ2 -0.012523)-0.018540λ2+2.00´10-4 λ2 ( l in mm, T=20 oC)
n2z =2.586179+0.013099/(λ2 -0.011893)-0.017968λ2-2.26´10-4 λ2 ( l in mm, T=20 oC)

Damage Threshold Comparison

Comparison of Bulk Damage Threshold (@1053nm ,1.3ns) 
Crystal Energy Density (J/cm2 ) Power Density (GW/cm 2 ) Ratio
KTP  6.0  4.6  1.00 
KDP  10.9  8.4  1.83 
BBO  12.9  9.9  2.15 
LBO 24.6 18.9 4.1

Capability

Common Specification
Dimension Tolerance (W±0.1mm)x(H±0.1mm)x(L+0.5/-0.1mm) (L≥2.5mm)
(W±0.1mm)x(H±0.1mm)x(L+0.2/-0.1mm) (L<2.5mm)
Clear aperture Central 90% of the diameter
Flatness ≤Lambda/8 @ 632.8nm
wavefront distortion ≤ Lambda/8 @ 632.8nm
Bevel ≤0.2mm@45°
Chip ≤0.1mm
Surface Quality S/D 10-5
Parallelism ≤ 20 arc seconds
Perpendicularity ≤ 5 arc minutes
Angle tolerance qD≤0.25°, fD≤0.25°
Damage threshold[GW/cm]:  >10 for 1064nm, TEM00, 10ns, 10HZ (polished only)
>1 for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
>0.5 for 532nm, TEM00, 10ns, 10HZ (AR-coated)
AR COATING Dual Band AR-coating (DBAR) of LBO for SHG of 1064nm.
   - low reflectance (R<0.2% at 1064nm and R<0.5% at 532nm );
   - high damage threshold (>500MW/cm2 at both wavelengths);
   - long durability.
Broad Band AR-coating (BBAR) of LBO for SHG of tunable lasers.

Other coatings are available upon request.