• Update:Jun 13, 2017
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LBO Lithium Triborate (LiB3O5 or LBO) is an excellent nonlinear optical crystal and it has the following features: lioad transparency range from 160nm to 2600nm high optical homogeneity ( n10-6) and being free of inclusion relatively large effective

Product Introduction

Lithium Triborate (LiB3O5 or LBO) is an excellent nonlinear optical crystal and it has the following features:

We can provide LBO crystals: 

Table 1. Chemical and Structural properties

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

Transparency Range 160-2600nm
SHG Phase Matchable Range 551 ~ 2600nm  (Type I)      790-2150nm (Type II)
Therm-optic Coefficient (°C, l in μm) dnx/dT=-9.3X10-6 dny/dT=-13.6X10-6 dnz/dT=(-6.3-2.1l)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 Coefficient 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

Figure 1. Transparency curve of LBO

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 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).

Figure 2. Optimum matching

 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.


Non-Critical Phase-Matching

Table 3. Properties of type I NCPM SHG at 1064nm

NCPM Temperature
Acceptance Angle
Walk-off Angle
Temperature Bandwidth
Effective SHG Coefficient
52 mrad-cm1/2
2.69 d36(KDP)

AS shown in table 3, Non-Critical Phase-Matching (NCPM) of LBO is featured by no walk-off, very wide acceptance angle and maximum effective coefficient. It promotes LBO to work in its optimal condition. SHG conversion efficiencies of more than 70% for pulse and 30% for cw Nd:YAG lasers have been obtained, with good output stability and beam quality.

As shown in Fig.3, type I and type II non-critical phase-matching can be reached along x-axis and z-axis at room temperature, respectively.

Figure 3.NCPM temperature tuning curves of LBO



LBO is an excellent NLO crystal for OPOs and OPAs with a widely tunable wavelength range and high powers. These OPO and OPA that are pumped by the SHG and THG of Nd:YAG laser and XeCl excimer laser at 308nm have been reported. The unique properties of type I and type II phase matching as well as the NCPM leave a big room in the research and applications of LBO’s OPO and OPA. Fig.4 shows the calculated type I OPO tuning curves of LBO pumped by the SHG, THG and 4HG of Nd:YAG laser in XY plane at the room temperature. And Fig. 5 illustrates type II OPO tuning curves of LBO pumped by the SHG and THG of Nd:YAG laser in XZ plane. 


LBO’s Spectral NCPM

Not only the ordinary non-critical phase matching (NCPM) for angular variation but also the noncritical phase matching for spectral variation (SNCPM) can be achieved in the LBO crystal. As shown in Fig.2, the phase matching retracing positions are λ1=1.31μm with θ =86.4°, φ=0° for Type I and λ2=1.30μm with θ=4.8°, φ=0° for Type II. The phase matching at these positions possess very large spectral acceptances Δλ. The calculated Δλ at λ1 and λ2are 57nm-cm-1/2 and 74nm-cm-1/2 respectively, which are much larger than the other NLO crystals. These spectral characteristics are very suitable for doubling broadband coherent radiations near 1.3μm, such as those from some diode lasers, and some OPA/OPO output without linewidth-narrowing components.

The crystal holder (free) and oven & Temperature Controller (for NCPM,OPO,OPA applications) are available for BBO & LBO.



1. LBO has a very low susceptibility to moisture. Users are advised to provide dry conditions for both the use  and preservation of LBO.
2. Polished surfaces of LBO requires precautions to prevent any damage.
3. We can select and design the best crystal for you, if the main parameters of your laser are  provided, such as energy per pulse, pulse width and repetition rate for a pulsed laser, power for a cw laser, laser beam diameter, mode condition, pergence, wavelength tuning range, etc.