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LBO Nonlinear Crystal

LBO (Lithium Triborate) is one of the most useful nonlinear material not just for its relatively large conversion coefficient – 3x that of KDP, but also for its excellent physical properties.

LBO is one of the most excellent non-linear crystals with a wide transparency range from 160nm to 2600nm. LBO crystal has a high damage threshold, moderately high nonlinear coupling and good chemical and mechanical properties. Its transmission range is from 0.21μm to 2.3 μm, LBO allows temperature-controllable non -critical phase-matching (NCPM) for 1.0-1.3 μm, Type I SHG, and also provides room temperature NCPM for Type II SHG at 0.8-1.1 μm. It possesses a relatively large angular acceptance bandwidth, reducing the beam quality requirements for source lasers.

Honor Optics is a professional stock/Large size/IBS coated LBO nonlinear crystal manufacturer, welcome to purchasing low absorption LBO nonlinear crystal.

Features of custom high purity LBO nonlinear crystal:

- Broad transparency range from 160-2600nm
- High optical homogeneity ( 1.0E-6/cm) and being free of inclusion;
- Medium effective SHG coefficient(about three times that of KDP)
- High damage threshold
- Wide acceptance angle and small walk-off
- Type I and type II non-critical phase matching (NCPM)
- Spectral NCPM near 1300nm
- Excellent mechanical and physical properties

Tab.1.Structural and Physical Properties

Crystal Structure Orthorhombic, Space group Pna21, Point group mm2
Cell Parameters a=8.4473Å,b=7.3788Å,c=5.1395Å,Z=2
Melting point 834°C
Optical homogeneity δn≈10-6/cm
Mohs hardness 6
Density 2.47 g/cm3
Thermal expansion coefficients αx=10.8x10-5/K,αy= -8.8x10-5/K,αz=3.4x10-5/K
Hygroscopic susceptibility Low
Absorption coefficient <0.01%/cm at 1064nm
Thermal conductivity 3.5W/mK

Tab. 2.Optical Properties

Transparency Range 160-2600nm
SHG Phase Matchable Range 551-2600nm  (Type I)      790-2150nm (Type II)
Therm-optic Coefficient (/℃, λ in μm) dnx/dT=-9.3X10-6
Absorption  Coefficients <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℃·cm   (Type I, 1064 SHG)
7.5℃·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 nx2=2.454140+0.011249/(λ2-0.011350)-0.014591λ2-6.60×10-5λ4
(λ in μm) ny2=2.539070+0.012711/(λ2-0.012523)-0.018540λ2+2.00×10-5λ4

Low-cost LBO nonlinear crystal has the largest damage threshold of all the commonly-used inorganic NLO crystals. Therefore, it is the best candidate for high average power SHG and other nonlinear optical processes.

Tab.3.Damage Threshold at 1053nm

Crystal Energy Density (J/cm2) Power Density (GW/cm2) Ratio

SHG and THG at Room Temperature

LBO is phase matched 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 in a wide wavelength range from 551nm to about 3000nm. high quality high damage threshold Chinese LBO nonlinear crystal is the first choice for making doubler or more triple for lasers such as Nd: YAG where high power density, high stability, and longtime operation are required.

SHG of custom high purity LBO nonlinear crystal

Non-Critical Phase-Matching

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. As shown, type I and type II non-critical phase-matching can be reached along the x-axis (θ=90°, φ=0°) and z-axis (θ=0°, φ=0°) at room temperature, respectively.

SHG conversion efficiencies of more than 70% for a pulse and 30% for CW Nd: YAG lasers, and THG conversion efficiency over 60% for pulse
Nd: YAG laser has been observed. With good output stability and beam quality.
Properties of type I NCPM SHG at 1064nm
NCPM Temperature 148°C
Acceptance Angle 52 brand-cm1/2
Walk-off Angle 0
Temperature Bandwidth 4°C-cm
Effective SHG Coefficient 2.69×d36(KDP)


LBO is an excellent NLO crystal for OPO and OPA with a widely tunable wavelength range and high powers. 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 OPO and OPA.

type I OPO tuning curves of custom high purity LBO nonlinear crystal

>1 for 1064nm, TEM00, 10ns, 10HZ (AR-coated)
>0.5 for 532nm, TEM00, 10ns, 10HZ (AR-coated)

Honour Optics provides the following LBO coatings:

Dual Band AR-coating (DBAR) of LBO for SHG of 1064nm. Low reflectance (R<0.1% at 1064nm and R<0.25%  at 532nm), super low reflectivity of R<0.05% at 1064nm  and  R<0.1% at 532nm is available upon request; 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.

Honour Optics standard specifications for LBO crystal

* Dimension tolerance: (W±0.05mm)x(H±0.05mm)x(L+/-0.1mm)
* Clear aperture: central 90% of the diameter
* No visible scattering paths or centers when inspected by a 50mW green laser
* Flatness: better than λ/10 @ 633nm
* Transmitting wavefront distortion: better than λ/8 @ 633nm
* Chamfer: ≤0.1mmx45°
* Chip: ≤0.1mm
* Scratch/Dig code: better than 10/ 5 to MIL-PRF-13830B
* Parallelism: better than 10 arc seconds
* Perpendicularity: ≤5 arc minutes
* Angle tolerance: Δθ≤0.25°, ΔΦ≤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)

With highly advanced polishing and coating technique and a good combination between them create our high-quality SHG and low-cost LBO nonlinear crystals.

We can customize crystal angle and size except for standard specification according to your request. It is available to re-polishing and coating for LBO crystals that you supply to us.

Standard applications of the custom high purity LBO nonlinear crystal

SHG and THG for middle and high power Nd: lasers at 1064nm for medical industrial and military applications;
SHG for Ti: Sapphire, Alexandrite, and Cr: LiSAF lasers;
SHG and THG of high power Nd: lasers at 1342nm &1319nm for red and blue laser
SHG for the Nd: Lasers at 914nm & 946nm for blue laser.
The VUV output at 187.7 nm is obtained by sum-frequency generation.
NCPM SHG over a broad wavelength range from 900nm-1700nm was measured.
Phase matching process cutoff: SHG-554 nm fundamental, THG-794 nm, SFM-down to 160 nm.
Optical Parametric Amplifiers (OPA) and Oscillators (OPO) application;

Honour Optics Warrant:

Strict quality control;
High inside quality without any defection.
Large crystal size up to 20x20x40mm3
High damage AR-coating
Large quantity standard products in-stock
Fast delivery. (for polished only, 1-2 weeks ARO. For coated crystal: 3-4 weeks ARO)
Quality Warranty Period: one year under proper use.

Honor Optics is a professional stock/Large size/IBS coated LBO nonlinear crystal manufacturer, welcome to purchasing low absorption LBO nonlinear crystal.

Honour Optics supplies and fabricates high quality high damage threshold Chinese LBO nonlinear crystal, size, and coating upon on your request.

Standard LBO able to ship within 4 weeks

Dimension(mm) θ(Deg) φ(Deg) Coating Application
3*3*10 42.2 90 AR/AR@1064&532/355nm THG@1064,TypeⅡ
3*3*10 90 11.6 AR/AR@1064&532nm SHG@1064,TypeⅠ
3*3*15 42.2 90 AR/AR@1064&532nm THG@1064,TypeⅡ
5*5*15 42.2 90 AR/AR@1064&532/355nm THG@1064,TypeⅡ
5*5*15 90 11.6 AR/AR@1064&532nm SHG@1064, TypeⅠ

Please be noted:

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 require precautions to prevent any damage.