Lithium Triborate (LiB3O5 , LBO)

Lithium Triborate (LiB3O5 or LBO) is an excellent nonlinear optical crystal, ATOM's LBO is featured by broad transparency range  

Introduction

Lithium Triborate (LiB3O5 or LBO) is an excellent nonlinear optical crystal, ATOMs LBO is featured by      broad transparency range from 160nm to 2600nm (see Figure 1);

   high optical homogeneity (dn»10-6/cm) and being free of inclusion, relatively large effective SHG coefficient (about three times that of KDP);

Description:

       high damage threshold;

   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.

 

                              Table 1. 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

 

   Table 2. Optical and Nonlinear Optical Properties of LBO

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=-9.3X10-6dny/dT=-13.6X10-6dnz/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/Vd32= -0.98 ± 0.09 pm/Vd33=0.05 ± 0.006 pm/V
Sellmeier  Equations(λ in μm)	nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60x10-5λ4ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.0x10-4λ4nz2=2.586179+0.013099/(λ2-0.011893)-0.017968λ2-2.26x10-4λ4

SHG and THG at Room Temperature

LBO is phase matchable for the SHG and THG of Nd:YAG and Nd:YLF lasers, using either type I or type II interaction. For the SHG at room temperature, type I phase matching  LBO can be reached and has the maximum effective SHG coefficient in the principal XY and XZ planes (see Fig. 2) in a wide wavelength range from 551nm to about 2600nm. The optimum type II phase matching falls in principal YZ and XZ planes(see Fig 2).

SHG conversion efficiencies of more than 70% for pulse and 30% for cw Nd:YAG lasers, and THG conversion efficiency over 60% for pulse Nd:YAG laser have been observed by using ATOMs LBO crystal.

LBO's applications

More than 480mW output at 395nm is generated by frequency doubling a 2W mode-locked Ti:Sapphire laser (<2ps, 82MHz). The wavelength range of 700-900nm is covered by a 5x3x8mm3 LBO crystal.* Over 80W green output is obtained by SHG of a Q-switched Nd:YAG laser in a type II 18mm long LBO crystal.* The frequency doubling of a diode pumped Nd:YLF laser (>500µJ @ 1047nm, <7ns, 0-10KHz) reaches over 40% conversion efficiency in a 9mm long LBO crystal.* The VUV output at 187.7 nm is obtained by sum-frequency generation.* 2mJ/pulse diffraction-limited beam at 355nm is obtained by intra-cavity frequency tripling a Q-switched Nd:YAG laser.

ATOM Warranty on LBO Specifications

* 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+0.1/-0.1mm) (L<2.5mm)* Clear aperture: central 90% of the diameter* No visible scattering paths or centers when inspected by a 50mW green laser* Flatness: less than λ/8 @ 633nm* Transmitting wavefront distortion: less than λ/8 @ 633nm* Chamfer: * Chip: ≤0.1mm* Scratch/Dig code: better than 10/ 5 to MIL-PRF-13830B* Parallelism: better than 20 arc seconds* Perpendicularity: ≤5 arc minutes* Angle tolerance: θ≤0.25°, Φ≤0.25°

* Damage threshold[GW/cm2 ]: >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)* Quality Warranty Period: one year under proper use.

Lithium Triborate (LiB3O5 , LBO)