Lithium Triborate (LiB3O5 or LBO) crystal，Lithium Triborate Crystal (LBO Crystal, LiB3O5 Crystal)

Product Information

Lithium Triborate Crystal (LBO Crystal, LiB3O5 Crystal) is an excellent high-power ultraviolet frequency doubling crystal.  An excellent nonlinear crystal with wide transparency range,It has a wide transparency range, moderately high nonlinear coupling, high damage threshold, and desirable chemical and mechanical properties.

LBO allows temperature-controlled Non-Critical Phase-Matching (NCPM) for 1.0-1.3 um, Type I SHG, and also provides room temperature NCPM for Type II SHG at 0.8-1.1 um. LBO crystal also possesses a relatively large angular acceptance bandwidth, reducing the beam quality requirements for pump lasers.LBO is 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 crystal  has been widely used in high average power second harmonic, sum frequency, difference frequency, third harmonic, fourth harmonic and parametric oscillation field.

ATT Crystal 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.

Synonyms

Lithium borate, LBO Crystal

Lithium Triborate Specification

Size：customized

     •　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 diameter
     •　No 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 code: 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)
    •　Quality Warranty Period: one year under proper use.

Per your request or drawing

We can customized as required

LBO has a low susceptibility to moisture. Users are advised to provide dry conditions for both the use and preservation of LBO. Polished surfaces of LBO requires precautions to prevent any damage. ATT engineers can select and design the best crystal for you, based on the main parameters of your laser, such as energy per pulse, pulse width and repetition rate for a pulsed laser, power for a cw laser, laser beam diameter, mode condition, divergence, wavelength tuning range, etc. For thin crystals, ATT can provide free holders for you..

Properties（Theoretical）

Optical and Nonlinear Optical Properties

LBO is featured by

      •　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.

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. SHG conversion efficiencies of more than 70% for pulse and 30% for cw Nd:YAG lasers have been obtained, with good output stability and beam quality. type  I and type II non-critical phase matching can be reached along x-axis and z-axis at room temperature, respectively.

LBO's OPO and OPA

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.

LBO's Spectral NCPM

Not only the ordinary non-critical phase matching (NCPM) for angular variation but also the non-critical phase matching for spectral variation (SNCPM) can be achieved in the LBO crystal. As shown in Fig.2, the phase matching retracing positions are λ1=1.31μm with θ =86.4°, φ=0° for Type I and λ2=1.30 μm with θ =4.8°, φ=0° for Type II. The phase matching at these positions possess very large spectral acceptances Δλ. The calculated Δλ at λ1 and λ2 are 57nm·cm and 74nm·cm respectively, which are much larger than that of other NLO crystals. These spectral characteristics are very suitable for doubling broadband coherent radiations near 1.3 μm, such as those from some diode lasers, and some OPA/OPO output without linewidth-narrowing components.

AR-coatings

ATT provides the following AR-coatings:

       •　Dual Band AR-coating (DBAR) of LBO for SHG of 1064nm.
        　low reflectance (R<0.2% at 1064nm and R<0.5%  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.

Applications of LBO

More than 480mW output at 395 nm is generated by frequency doubling a 2W mode-locked Ti:Sapphire laser ( < 2ps, 82MHz).  The wavelength range of 700 – 900 nm is covered by a 5x3x8mm3 LBO crystal.

Over 80W green output is obtained by SHG of a  Q-switched Nd:YAGlaser in a type II 18 mm long LBO  crystal.

The frequency doubling of a diode pumped Nd:YLFlaser (>500µJ @ 1047 nm, < 7 ns, 0-10KHz) reaches over 40% conversion efficiency in a 9 mm long LBO      crystal.

The VUV output at 187.7 nm is obtained by  sum-frequency generation.

2mJ/pulse diffraction-limited beam at 355 nm is  obtained by intra-cavity frequency tripling a  Q-switched Nd:YAG laser. LBO’s Non-Critical Phase-Matching

By using LBO crystal,over 11W of average power at  532nm was obtained by extra-cavity SHG of a 25W Antares mode-locked Nd:YAG      laser (76MHz, 80ps).

By using LBO crystal, 20W green output was generated by frequency doubling a medical, multi-mode Q-switched Nd:YAG laser. Much higher green output is expected with higher input.

A quite high overall conversion efficiency and 540 – 1030 nm tunable wavelength range were obtained with OPO pumped at 355nm.

Type I OPA pumped at 355 nm with the pump-to-signal  energy conversion efficiency of 30% has been reported.

Type II NCPM OPO pumped by a XeCl excimer laser at  308 nm 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 532 nm was also observed to cover a wide  tunable range from 750nm to 1800 nm by temperature tuning from 106.5°C to 148.5°C.

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 (0.15 nm) and high pump-to-signal energy  conversion efficiency (32.7%) were obtained when it is pumped by a 4.8mJ,  30ps laser at 354.7 nm. Wavelength tuning range from 482.6 nm to 415.9 nm was covered by increasing the temperature of LBO or rotating BBO.

Packing of LBO

Standard Packing:

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 440 gallon liquid totes Special package is available on request.

ATTs’ LBO is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition.

Chemical Identifiers