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NLO Crystal


LBO nonlinear crystal

LBO (LiB3O5)* is a nonlinear optical crystal perfectly suited for harmonic generation as well as sum frequency mixing and OPO applications using widely spread Nd lasers, Ti:Sapphire and Dye lasers. Such physical LBO properties as excellent optical homogeneity, non hygroscopicity and very high damage threshold assure long and stabile operation of crystal. LBO crystal is the first choice as harmonic generator of high peak power pulsed lasers.

Dayoptics can provide large aperture LBO crystals which can be used for harmonic generation and OPO of high average/peak power Q-switched Neodymium lasers, where other crystals can't withstand. Non-critical phase matching in wide range achievable by temperature tuning allows to employ long crystals without any walk-off influence on nonlinear interaction efficiency. Especially this application is attractive for CW and quasi-CW lasers.

Dayoptics standard LBO crystals specification:
Width and height: Max 15 x 15 mm
Length: Max 18mm
Flatness: l/6 at 633 nm
Parallelism < 10 arcsec
Surface quality: 10/5 scr/dig as per MIL-O-13830A
Perpendicularity: < 5 arcmin
Angle tolerance : < 15 arcmin
Clear aperture: 90% of full aperture
Physical and optical Properties:
Crystal Structure Orthorhomic,Space group Pna21
Point group mm2
Lattice Parameters a = 8.4473Å, a = 7.3788Å, c = 5.1395Å, z = 2
Melting Point About 8340C
Mohs Hardness 6
Density 2.47 g/cm3
Thermal Expansion Coefficient ax = 10.8 x 10-5/K av = -8.8 x 10-5/K az = 3.4 x 10-5/K
Absorption Coefficient < 0.1%/cm at 1664 nm
< 0.3%/cm at 532 nm
Transparency Range:
160 - 2600 nm, See Transparency Curve
LBO Transparency
Curve(Tickness=10mm)
Refractive Indices:
Wavelength
1.0642 mm nx = 1.5656, nv = 1.5905, ne = 1.6055
0.5321 mm nx = 1.5785, nv = 1.6065, ne = 1.6212
0.2660 mm nx = 1.5973, nv = 1.6286, ne = 1.6444
Therm-Optic Coefficients:
dno/dT = - 9.3 x 10-6/0C
dne/dT = -13.6 x 10-6/0C
dne/dT = (-6.3+2.1l) x 10-6/0C		 　
Sellmeier Equations:
N2x = 2.454140+0.011249/(l2-0.011350)-0.014591l2 - 6.60 x 10-5/l4 ( l in mm, T=200C)
N2y = 2.539070+0.012711/(l2-0.012523)-0.018540l2 + 2.00 x 10-4/l4 ( l in mm, T=200C)
N2z = 2.586179+0.013099/(l2-0.011893)-0.017968l2 - 2.26 x 10-4/l4 ( l in mm, T=200C)

The effective SHG coefficient of LBO is three times that of KDP for SHG of 1064 nm. For the point group mm2 of LBO, the non-vanished NLO susceptibilities are: d31 =1.05±0.09 pm/V; d32 = -0.98±0.09 pm/V; d33 =0.05±0.006 pm/V.

The temperature acceptane of LBO is smaller than BBO. The temperature acceptance of LBO for SHG and 4HG are: SHG: 1064+1064 → 532 nm T=5.8 0C/cm, THG: 1064+355 → 266nm DT=3.8 0C/cm.

LBO has a very high damage threshold (the highest among all the commonly used NLO crystals). It is the best candidate for high average power SHG and other NLO processes.the table to the right compares the damage thresholds of LBO and other crystals in a 1.3 ns Nd:YLF laser at 1053 nm.

Crystal Energy Density(J/cm2) Power Density(GW/cm2) 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 4.10