LBO 結晶 非線形光学結晶(NLO)

Lithium Triborate (LiB3O5, LBO)



LBO 結晶: Lithium Triborate (LiB3O5 or LBO) は非常に優れた非線形光学結晶で、FIRSM, CAS (Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences) 中国科学院 福建省物質構造研究所にて発見され開発された非線形光学結晶になります。
CASTECH社 (旧Fujian CASTECH Crystals, Inc.)は特許取得されたLBO 結晶と非線形光学デバイスの製造・生産・販売の唯一の正式な権利を持つ企業になります。

特許番号は 米国: 4,826,283, 日本: 2023845,中国: 88 1 02084.2となります

LBO 非線形光学結晶は数量1つから販売しております。
LBO 非線形光学結晶ご購入の際は、ご希望のサイズ ご希望のコーティング 数量をお知らせください

LBO 結晶ご使用の注意点とお知らせ

  • LBO 結晶は湿気を嫌います。ご使用中また、保管もドライコンディションを心がけください
  • LBO 結晶の研磨後の結晶表面はダメージが入りやすいため取り扱いに注意が必要です。
  • LBO 結晶の最適の結晶サイズがお分かりにならない場合は、私共にお気軽にご相談ください。最適のLBO 結晶をご提案させていただきます。ご使用のレーザーのエネルギー、パルス幅、発振周波数(繰り返し)CWレーザーでしたら、平均出力、ビームの直径、縦モード、横モードの状態、ビーム広がり角、波長チューニングレンジ等、詳細なパラメーターをお知らせください。
  • 厚さが薄いLBO 結晶をご注文の際は、無料でホルダーをご提供させていただきます。

CASTECH 社製 LBO 結晶の持つ特徴

  • 160nmから2600nmまでの広い透過域を持ちます。
  • 異質物を含まず、高い光学的均一性を持ちます。 (dn»10-6/cm)
  • 相対的に大きい効果的なSHG係数を持ちます。(おおよそKDP 結晶の3倍です。)
  • 高いダメージ閾値をもちます。
  • 広い受け入れ角度を持ち、ウォークオフは小さいです。
  • タイプ I 及び タイプ II 結晶のnon-critical phase matching (NCPM) は広い波長域となっています。(spectral NCPM near 1300nm.)

LBO 結晶にCASTECH社が提供しておりますサービスについて

  • 厳格な品質管理体制のもと製造しております。
  • 最大結晶サイズは 30x30x30mm3 最長は60mmまで可能です。
  • AR-コーティング、マウント、再研磨サービス
  • 大量の結晶を在庫として保有しております。
  • 迅速な出荷が可能です。

LBO 結晶の化学特性及び構造特性

Crystal Structure Orthorhombic, Space group Pna21, Point group mm2
Lattice Parameter a=8.4473 Å, b=7.3788 Å , c=5.1395 Å , Z=2
Melting Point About 834℃
Mohs Hardness 6
Density 2.47 g/cm3
Thermal Conductivity 3.5 W/m/K
Thermal Expansion Coefficient ax=10.8×10-5/K, ay= -8.8×10-5/K, az=3.4×10-5/K

LBO 結晶の光学特性及び非線形光学特性

Transparency Range 160-2600 nm
SHG Phase Matchable Range 551 – 2600 nm  (Type I)      790-2150 nm (Type II)
Therm-optic Coefficient
(℃, λ in µm)
Absorption  Coefficient <0.1 %/cm at 1064 nm    <0.3 %/cm at 532 nm
Angle Acceptance 6.54 mrad-cm    (φ, Type I,1064 SHG)
15.27 mrad-cm    (θ, Type II,1064 SHG)
Temperature Acceptance 4.7 ℃-cm   (Type I, 1064 SHG)
7.5 ℃-cm   (Type II,1064 SHG)
Spectral Acceptance 1.0 nm-cm (Type I, 1064 SHG)
1.3 nm-cm (Type II,1064 SHG)
Walk-off Angle 0.60° (Type I  1064 SHG)
0.12° (Type II  1064 SHG)
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
d31=1.05 ± 0.09 pm/V
d32= -0.98 ± 0.09 pm/V
d33=0.05 ± 0.006 pm/V
Sellmeier  Equations
(λ in µm)

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 by using CASTECH’s LBO crystal.

LBO 結晶の応用例

* 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 intra-cavity frequency tripling a Q-switched Nd:YAG laser.

LBO 結晶のNon-Critical Phase-Matching

Table 3. Properties of type I NCPM SHG at 1064nm

NCPM Temperature
Acceptance Angle
Walk-off Angle
Temperature Bandwidth
Effective SHG Coefficient

52 mrad-cm1/2
2.69 d36(KDP)


AS shown in table 3, 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.

As shown in Fig.3, type I and type II non-critical phase-matching can be reached along x-axis and z-axis at room temperature, respectively.(CASTECH develops an assembly of oven and temperature controller for NCPM applications. Please refer to Page 20 for more technical data.)

LBO’s applications

* 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.

LBO 結晶を用いた OPO 及び OPA

LBO is an excellent NLO crystal for OPOs and OPAs with a widely tunable wavelength range and high powers. These OPO and OPA that 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 big room in the research and applications of LBO’s OPO and OPA. Fig.4 shows the calculated type I OPO tuning curves of LBO pumped by the SHG, THG and 4HG of Nd:YAG laser in XY plane at the room temperature. And Fig. 5 illustrates type II OPO tuning curves of LBO pumped by the SHG and THG of Nd:YAG laser in XZ plane.

LBO’s applications

* 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°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 (0.15nm) 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 by increasing the temperature of LBO or rotating BBO.

LBO’s Spectral NCPM

Not only the ordinary non-critical phase matching (NCPM) for angular variation but also the noncritical 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=1.30μm 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 λ2are 57nm-cm-1/2 and 74nm-cm-1/2 respectively, which are much larger than the other NLO crystals. These spectral characteristics are very suitable for doubling broadband coherent radiations near 1.3μm, such as those from some diode lasers, and some OPA/OPO output without linewidth-narrowing components.

The crystal holder (free) and oven & Temperature Controller (for NCPM,OPO,OPA applications) are available for BBO & LBO.

LBO 結晶に可能なARコーティング

CASTECH provides LBO crystal with 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 );
· high damage threshold (>500MW/cm2at both wavelengths);
· long durability.
* Broad Band AR-coating (BBAR) of LBO for SHG of tunable lasers.
* Other coatings are available upon request.

LBO 結晶の仕様及び、保証

* 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: ≤0.2mmx45°
* 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: Δθ≤0.25°, ΔΦ≤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.


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.
3. CASTECH engineers can select and design the best LBO crystal for you, if the main parameters of your laser are  provided, 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.
4. For thin LBO crystal, CASTECH can provide free holder for you.

LBO 非線形光学結晶は数量1つから販売しております。
LBO 非線形光学結晶ご購入の際は、ご希望のサイズ ご希望のコーティング 数量をお知らせください。