LBO Crystal


  • 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: 2.47g/cm3
  • Thermal Expansion Coeficients: αx=10.8x10-5/K, αy=-8.8x10-5/K,αz=3.4x10-5/K
  • αx=10.8x10-5/K, αy=-8.8x10-5/K,αz=3.4x10-5/K: 3.5W/m/K
  • Product Detail

    Technical parameters

    LBO (Lithium Triborate - LiB3O5) is now the most popularly used material for Second Harmonic Generation (SHG) of 1064nm high power lasers (as a substitute to KTP) and Sum Frequency Generation (SFG) of 1064nm laser source to achieve UV light at 355nm.
    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 2600nm. 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.
    LBO is an excellent NLO crystal for OPOs and OPAs with a widely tunable wavelength range and high powers. These OPO and OPA which 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 large room in the research and applications of LBO's OPO and OPA.
    Advantages:
    • Broad transparency range from 160nm to 2600nm ;
    • High optical homogeneity (δn≈10-6/cm) and being free of inclusion;
    • Relatively large 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) in a wide wavelength range;
    • Spectral NCPM near 1300nm.
    Applications:
    • More than 480mW output at 395nm is generated by frequency doubling a 2W mode-locked Ti:Sapphire  laser (<2ps, 82MHz). The wavelength range of  700-900nm is covered by a 5x3x8mm3 LBO crystal.
    • Over 80W green output is obtained by SHG of a Q-switched Nd:YAG laser in a type II 18mm long LBO crystal.
    • The frequency doubling of a diode pumped Nd:YLF laser (>500μJ @ 1047nm,<7ns, 0-10KHz) reaches over 40% conversion efficiency in a 9mm long LBO crystal.
    • The VUV output at 187.7 nm is obtained by sum-frequency generation.
    • 2mJ/pulse diffraction-limited beam at 355nm is obtained by intracavity frequency tripling a Q-switched Nd:YAG laser.
    •  A quite high overall conversion efficiency and 540-1030nm tunable wavelength range were obtained with OPO pumped at 355nm.
    • Type I OPA pumped at 355nm with the pump-to-signal energy conversion efficiency of 30% has been reported.
    • Type II NCPM OPO pumped by a XeCl excimer laser at 308nm has achieved 16.5% conversion efficiency, and moderate tunable wavelength ranges can be obtained with different pumping sources and temperature tuning.
    • By using the NCPM technique, type I OPA pumped by the SHG of a Nd:YAG laser at 532nm was also observed to cover a wide tunable range from 750nm to 1800nm by temperature tuning from 106.5℃ to 148.5℃.
    • By using type II NCPM LBO as an optical parametric generator (OPG) and type I critical phase-matched BBO as an OPA, a narrow linewidth (0.15nm) and high pump-to-signal energy conversion efficiency (32.7%) were obtained when it is pumped by a 4.8mJ, 30ps laser at 354.7nm. Wavelength tuning range from 482.6nm to 415.9nm was covered either by increasing the temperature of LBO or by rotating BBO.

    Basic 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

    2.47g/cm3

    Thermal Expansion Coeficients

    αx=10.8×10-5/K, αy=-8.8×10-5/K,αz=3.4×10-5/K

    Thermal Conductivity Coefficients

    3.5W/m/K

    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
    dny/dT=-13.6X10-6
    dnz/dT=(-6.3-2.1λ)X10-6

    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)

     

    Technical Parameters
    Dimension tolerance (W±0.1mm)x(H±0.1mm)x(L+0.5/-0.1mm) (L≥2.5mm)(W±0.1mm)x(H±0.1mm)x(L+0.1/-0.1mm) (L<2.5mm)
    Clear aperture central 90% of the diameterNo visible scattering paths or centers when inspected by a 50mW green laser
    Flatness less than λ/8 @ 633nm
    Transmitting wavefront distortion less than λ/8 @ 633nm
    Chamfer ≤0.2mm x 45°
    Chip ≤0.1mm
    Scratch/Dig better than 10/ 5 to MIL-PRF-13830B
    Parallelism better than 20 arc seconds
    Perpendicularity ≤5 arc minutes
    Angle tolerance △θ≤0.25°, △φ≤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)