Description:
Lithium triborate (LiB3O5) LBO is an excellent non-linear optics crystal, which has a wide transparency range, high damage threshold, moderately high nonlinear coupling and desirable chemical and mechanical properties. LBO crystals have been widely used in second harmonic generation (SHG), for example of Nd:YAG lasers (1064 nm ⇒ 532 nm). LBO can be both critically and non-critically phase-matched.
Thanks to its large spectral transmission range as well as noncritical phase matching (NCPM) in the near IR region, LBO crystals have been applied in non-linear optical applications like OPO, OPA, OPCPA and other. Since its broad gain bandwidth overlaps with Ti:Sapphire in 800 nm range, ultra-high power and high contrast laser systems have been built based on the mixed CPA/OPCPA plan.
Features:
1.Wide transmission region from 160 nm to 2600nm
2.Large effective second-harmonic-generation (SHG) coefficient (about three times that of KDP)
3.Good mechanical and physical properties
4.High damage threshold of 18.9 GW/cm2 for a 1.3 ns laser at 1053 nm
5.Both Type I and II NCPM in a wide wavelength range is possible
6.Wide acceptance angle and small walk-off
7.High optical homogeneity with δn≈10-6/cm
8.Spectral NCPM near 1300 nm
Applications:
1.Frequency doubling and tripling of Nd:YAG and Nd:YLF lasers.
2.SHG and THG for middle and high power Nd: lasers at 1064 nm for medical, industrial and military applications
3.SHG and THG of high power Nd: lasers at 1342 nm & 1319 nm for red and blue laser
4.Optical parametric amplifiers (OPA) and oscillators (OPO) pumped by Excimer lasers and harmonics of Nd:YAG lasers.
5.Optical parametric chirped pulse amplification (OPCPA) in ultrafast pulse system
Chemical and Physical Properties:
Property | Value |
Chemical formula | LiB3O5 |
Crystal structure | Orthorhombic, Space group Pna21, Point group mm2 |
Lattice Parameter | a=8.4473Å ,b=7.3788Å, c=5.1395Å, Z=2 |
Mass density | 2.47 g/cm3 |
Moh hardness | 6 |
Melting point | About 834°C |
Thermal conductivity | 3.5W/m/K |
Thermal expansion coefficient | ax=10.8x10-5/K, ay= -8.8x10-5/K, az=3.4x10-5/K |
Birefringence | Negative biaxial crystal: 2Vz = 109.2° at λ = 0.5321μm |
Linear Optical Properties:
Property | Value |
Transparency Range | 169 - 2600 nm |
Absorption Coefficient: | <0.1%/cm at 1064nm <0.3%/cm at 532nm |
Refractive Indices at 1.0642 mm at 0.5321 mm at 0.2660 mm | nx = 1.5656, ny = 1.5905, nz=1.6055 nx = 1.5785, ny = 1.6065, nz=1.6212 nx = 1.5973, ny = 1.6286, nz=1.6444 |
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 |
Nonlinear Optical Properties:
Property | Value |
SHG Phase Matchable Range | 551 ~ 2600nm (Type I) 790-2150nm (Type II) |
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 |
Therm-Optic Coefficients (°C, λ in μm) | dnx/dT=-9.3X10-6 dny/dT=-13.6X10-6 dnz/dT=(-6.3-2.1λ)X10-6 |
Angle Acceptance | 6.54mrad-cm (Φ, Type I,1064 SHG) 15.27mrad-cm (q, Type II,1064 SHG) |
Damage Threshold at 1.064 mm at 0.532 mm | 9 GW/cm2 (9 ns); 19 GW/cm2 (1.3 ns) 2.2 GW/cm2 (10 ns); 45 GW/cm2 (100 ps) |
Polishing Specification:
Property | Value |
Orientation Tolerence | < 0.5° |
Thickness/Diameter Tolerance | ±0.05 mm |
Surface Flatness | <λ/8@632 nm |
Wavefront Distortion | <λ/4@632 nm |
Surface Quality | 10/5 |
Parallel | 30'' |
Perpendicular | 15' |
Clear Aperture | >90% |
Chammfer | <0.2×45° |
Standard products:
Crystal dimension/mm | Length/mm | Application | Orientation Theta/Phi deg | AR Coatings S1/S2, nm/nm |
3 x 3 | 10 | THG@1064nm, Type II (e-oe) | 42.2/90 | 1064 + 532 / 355 |
3 x 3 | 15 | SHG@1064nm, NCPM I Type | 90/0 | 1064 + 532 / 1064 + 532 |
5 x 5 | 15 | SHG@1064nm, Type I (e-oo) | 90/11.6 | 1064 + 532 / 1064 + 532 |
6 x 6 | 0.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
6 x 6 | 1.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
6 x 6 | 2.8 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
6 x 6 | 3.7 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
8 x 8 | 0.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
8 x 8 | 1.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
8 x 8 | 2.8 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
10 x 10 | 0.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
10 x 10 | 1.9 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
10 x 10 | 2.8 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
10 x 10 | 3.7 | SHG@1030nm | 90/13.8 | 515 + 1030 / 515 + 1030 |
3 x 3 | 15 | THG@1064nm, Type II (e-oe) | 42.2/90 | 1064 + 532 / 355 |
3 x 3 | 15 | SHG@1064nm, Type I (e-oo) | 90/11.6 | 1064 + 532 / 1064 + 532 |
3 x 3 | 20 | SHG@1064nm, NCPM I Type | 90/0 | 1064 + 532 / 1064 + 532 |
5 x 5 | 15 | THG@1064nm, Type II (e-oe) | 42.2/90 | 1064 + 532 / 355 |
3 x 3 | 10 | SHG@1064nm, Type I (e-oo) | 90/11.6 | 1064 + 532 / 1064 + 532 |
Q&A
Q: What is phase mismatching?
A: A group of techniques for achieving efficient nonlinear interactions in a medium. Many phase-sensitive nonlinear processes, in particular parametric processes such as frequency doubling, sum and difference frequency generation, parametric amplification and oscillation, and also four-wave mixing, require phase matching to be efficient. Essentially, this means ensuring that a proper phase relationship between the interacting waves (for optimum nonlinear frequency conversion) is maintained along the propagation direction. Only if that condition is fulfilled, amplitude contributions from different locations to the product wave are all in phase at the end of the nonlinear crystal.
Q: What is Second harmonic generation (SHG)?
A: SHG is a nonlinear optical process, in which photons with the same frequency interacting with a nonlinear material are effectively "combined" to generate new photons with twice the energy, and therefore twice the frequency and half the wavelength of the initial photons.