Crystals NLO Crystals LBO

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1 Crystals NLO Crystals LBO Introduction Lithium triborate (LiB 3 O 5 or LBO) has the following exceptional properties that make it a very important nonlinear crystal: LBO has following advance: absorption: <50ppm/cm for high power laser aoolication High damage coating for high power cw laser. Large quantity standard products in stock Low price Lbo crystals advanced 1. broad transparency range from 160nm to 2600nm; 2. high optical homogeneity ( d n» 10-6 /cm) and being free of inclusion; 3. relatively large effective SHG coefficient (about three times that of KDP); 4. high damage threshold (18.9 GW/cm 2 for a 1.3ns laser at 1053nm); 5. wide acceptance angle and small walk-off; 6. type I and type II non-critical phase matching (NCPM) in a wide wavelength range; 7. spectral NCPM near 1300nm. LBO is grown with the flux method. It is a negative biaxial crystal, with the principal axes X, Y, and Z (n z >n y >n x ) parallel to the crystallographic axes a, c, and b, respectively.

2 Structural and Physical Properties: Crystal Structure: Orthorhombic, Space group Pna2 1, Point group mm2 Cell Parameters: a= Å, b= Å, c= Å, Z=2 Melting point: About 834 C Optical homogeneity: d n» 10-6 /cm Mohs hardness: 6 Density: 2.47 g /cm 3 Thermal expansion coefficients: a x =10.8x10-5 /K, a y = -8.8x10-5 /K, a z =3.4x10-5 /K Hygroscopic susceptibility: Low Absorption coefficient: <0.01%/cm at 1064nm Thermal conductivity: 3.5 W/mK Linear Optical Properties: Transparency range: Sellmeier equations: ( l in m m) Refractive indices: at 1064 nm at 532 nm at 266 nm Therm-optic coefficients: (/K, l in m m) nm n 2 x = /( l ) l x10-5 l 4 n 2 y = / ( l ) l x10-4 l 4 n 2 z = /( l ) l x10-4 l 4 n x = , n y = , n z = n x = , n y = , n z = n x = , n y = , n z = Dn x /dt = -1.8x 10-6 dn y /dt = x 10-6 Dn z /dt = ( l ) x 10-6 Nonlinear Optical Properties: NLO coefficients: Effective nonlinearity expressions d 31 =1.05 ± 0.09 pm/v d 32 = ± 0.09 pm/v d 33 =0.05 ± pm/v d ooe =d 32 cos (in XY plane) d eeo =d 31 cos 2 +d 32 sin 2 (in XZ plane) d oeo =d 31 cos (in YZ plane)

3 Damage threshold: at 1064nm at 532nm d eoe =d 31 cos 2 +d 32 sin 2(in XZ plane) 9GW/cm 2 (9 ns); 19 GW/cm 2 (1.3 ns) 2.2 GW/cm 2 (10 ns); 45 GW/cm 2 (100 ps) LBO has the highest damage threshold in all the commonly-used inorganic NLO crystals. Therefore, it is the best candidate for high average power SHG and other nonlinear optical processes. Damage Threshold at 1053nm Crystal Energy Density (J/cm 2 ) Power Density (GW/cm 2 ) Ratio KTP KDP BBO LBO LBO's applications 1. SHG and THG for middle and high power Nd: lasers at 1064nm for medical, industrial and military applications; 2. SHG for Ti:Sapphire, Alexandrite and Cr:LiSAF lasers; 3. SHG and THG of high power Nd: lasers at 1342nm & 1319nm for red and blue laser 4. SHG for the Nd: Lasers at 914nm & 946nm for blue laser. 5. The VUV output at nm is obtained by sum-frequency generation. 6. NCPM SHG over a broad wavelength range from 900nm-1700nm was measured. 7. Phase matching process cutoff: SHG-554 nm fundamental, THG-794 nm, SFMdown to 160 nm. 8. Optical Parametric Amplifiers (OPA) and Oscillators (OPO) application; 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 in a wide wavelength range from 551nm to about 3000nm. LBO is the first choice for making doubler or tripler for lasers such as Nd:YAG where high power density, high stability, and long time operation are required.

4 SHG tuning curves of LBO NCPM temperature tuning curves of LBO 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 x-axis ( q =90, f =0 ) and z-axis ( q =0, f =0 ) at room temperature, respectively. 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. with good output stability and beam quality. Properties of type I NCPM SHG at 1064nm NCPM Temperature 148 C Acceptance Angle 52 mrad-cm 1/2 Walk-off Angle 0 Temperature Bandwidth 4 C-cm Effective SHG Coefficient 2.69 d 36 (KDP) LBO's OPO and OPA LBO is an excellent NLO crystal for OPOs and OPAs 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 LBO's OPO and OPA. LBO Specifications

5 Transmitting wavefront distortion: less than l 633nm Dimension tolerance: (W ± 0.1mm )x(h ± 0.1mm )x(l+0.2/ -0.1mm ) Clear aperture: central 90% of the diameter No visible scattering paths or centers when inspected by a 50mW green laser Flatness: l 633nm Scratch/Dig code: 10/ 5 to MIL-O A Parallelism: better than 20 arc seconds Perpendicularity: 5 arc minutes Angle tolerance: D q < ± 0.2, D f < ± 0.2 Coating: High Damage Threshold DBAR and THG coating for 1064nm laser Quality Warranty Period: one year under proper use. NOTE 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. Standard Products Part No. Dimension Application Coating Type LBO1320 3x3x 20mm SHG@1064nm DBAR coating I LBO1316 3x3x 16mm SHG@1064nm DBAR coating I LBO1312 3x3x 12mm SHG@1064nm DBAR coating I LBO1418 4x4x 18mm SHG@1064nm DBAR-coating I LBO0320 3x3x 20mm NCPM for SHG@1064nm Uncoating I LBO2320 3x3x 20mm THG for 1064nm AR coating II LBO2316 3x3x 16mm THG for 1064nm AR coating II LBO2418 4x4x 18mm THG for 1064nm AR coating II LBO2415 4x4x 15mm THG for 1064nm AR coating II LBO1340 3x3x 40mm NCPM for SHG@1064nm Uncoating