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BBO Nonlinear Crystal

BBO (Beta-Barium borate or β-BaB2O4 ) is most versatile non-linear optical crystals thanks to its unique features, e.g. broad transmission, and phase matching ranges, large non-linear coefficient, high damage threshold, and excellent optical homogeneity.

BBO crystal has large effective second harmonic generation (SHG) coefficient about 6 times greater than that of KDP crystal, as well as excellent electro-optic crystal applied in the application of high power laser system.

BBO crystals an efficient NLO crystal widely used in Tunable lasers: Dye lasers, Ultrafast Pulse lasers, Ti:Sapphire and Alexandrite lasers, Argon Ion and Copper-Vapor lasers. BBO’s OPO and OPA are powerful tools for generating a widely tunable coherent radiation from the UV to IR.

There is another form of BBO with the different crystal structure, which is called alpha-BBO, known as a-BBO. Alpha-BBO is a good UV birefringent crystal and is widely used these days in UV polarizing prism. BBO crystals are also widely used as the electro-optical material in various Pockels cells and modulators. Honour Optics is the professional purchasing large size BBO nonlinear crystal manufacturer, buy low-cost BBO nonlinear crystal at factory price.

Honour Optics manufactures standard Type I and Type II BBO crystals for SHG/THG/4HG/5HG applications, our BBO crystal length from 0.005mm to 25mm and size up to 15x15x15mm, with P-coatings or AR coatings. We could offer thin BBO crystal with 0.005mm thickness. We also offer polishing and re-working services.

Typical Features of BBO crystal:

1.Broad phase-matching range from 409.6 nm to 3500 nm
2.Extensive optical transmission from 190 nm to 3500 nm
3.Large effective second-harmonic-generation (SHG) coefficient
4.High damage threshold of 10 GW/cm2 for 100 ps pulse-width at 1064 nm
5.Wide temperature-bandwidth of about 55℃
6.Excellent mechanical and physical properties

BBO is an efficient nonlinear crystal for the second (SHG), third (THG) and fourth (4HG) harmonic generations of Nd:YAG lasers; and is the only crystal can be used for the fifth (5HG) harmonic generation at 213nm. Conversion efficiencies of more than 70% for SHG, 60% for THG and 50% for 4HG, and 200 mW output at 213nm (5HG) have been obtained respectively. Because of BBO'S high efficiency, no hygroscopic after coating, and large size available, it replaces KD'P in most of the frequency doubling of Nd:YAG lasers.

Custom BBO nonlinear crystal is also an efficient crystal for the intracavity SHG of high power Nd:YAG lasers. For the intracavity SHG of an acousto-optic Q-switched Nd:YAG laser, more than 15W average power at 532nm was generated from our AR-coated BBO crystal. When it is pumped by the 600mW SHG output of a mode-locked Nd:YLF laser, 66mW output at 263nm was produced from a Brewster-angle-cut BBO in an external enhanced resonant cavity.
Because of a small acceptance angle and large walk-off, good laser beam quality is the key for BBO to obtain high conversion efficiency. Welcome everyone to wholesale BBO nonlinear crystal.

Tab.1.Structural and Physical Properties

Crystal Structure trigonal, space group R3c
Cell Parameters a = b = 12.532Ä, c = 12.717Ä, Z = 6
Melting Point 1095 +/-5°C
Transition Temperature 925 +/-5°C
Optical Homogeneity Dn ≈10-6/cm
Hardness 4.5 Mohs
Density 3.85 g/cm3
Absorption Coefficient < 0.1%/cm (at 1064 nm)
Hygroscopic Susceptibility low
Resistivity > 1011 ohm-cm
Relative Dielectric Constant eT11/e0: 6.7, eT33/e0: 8.1
Tan d, < 0.001
Thermal Expansion Coefficients(in the range of 25°C- 900°C) a, 4 x 10-6/K
c, 36 x 10-6/K
Thermal Conductivity ^c, 1.2 W/m/K; ||c, 1.6 W/m/K

Honour's BBO is widely used in the Dye lasers. With type I sum-frequency of 780-950nm and 248.5nm (SHG output of 495nm dye laser) in BBO, the shortest UV outputs ranging from 188.9nm to 197 nm and the pulse energy of 95mJ at 193nm and 8mJ at 189nm have been obtained respectively.

Frequency-doubling and a tripling of ultrashort-pulse lasers are the applications in which BBO shows superior properties to KDP and ADP crystals. We can provide as thin as 0.005mm BBO for this purpose. A 10fs short laser pulse can be efficiently frequency-doubled with a thin BBO, in terms of both phase-velocity and group-velocity matching.

UV output in the region 360nm - 390 nm with pulse energy of 105 mJ (31% SHG efficiency) at 378 nm, and output in the region 244nm - 259nm with 7.5mJ (24% mixing efficiency) have been obtained for type I SHG and THG of an Alexandrite laser in BBO nonlinear crystal. More than 50% of SHG conversion efficiency in a Ti:Sapphire laser has been obtained. High conversion efficiencies have been also obtained for the THG and 4HG of Ti:Sapphire lasers.

By employing the intracavity frequency-doubling technique in an Argon Ion laser with all lines output power of 2W, maximum 33mW at 250.4 nm and thirty-six lines of deep UV wavelengths ranging from 228.9 nm to 257.2 nm were generated in a B-cut BBO crystal. Up to 230 mW average power in the UV at 255.3 nm with maximum 8.9% conversion efficiency was achieved for the SHG of a Copper-Vapor laser at 510.6 nm.

Tab. 2.Chemical Properties

Phase-matchable SHG range 189-1750nm
NLO coefficients d11 = 5.8 x d36(KDP)
d11 = 0.05 x d11, d22< 0.05 x d11
Electro-Optic Coefficients g11 = 2.7 pm/V, g22, g31< 0.1 g11
Half-Wave Voltage 48 KV (at 1064 nm)
Damage Threshold
at 1.064 mm
at 0.532 mm
5 GW/cm2 (10 ns);
10 GW/cm2 (1.3 ns)1 GW/cm2 (10 ns);
7 GW/cm2 (250 ps)
Transparency Range 189 - 3500 nm
Refractive Indices
at 1.0642 mm
at 0.5321 mm
at 0.2660 mm
ne = 1.5425, no = 1.6551
ne = 1.5555, no = 1.6749
ne = 1.6146, no = 1.7571
Therm-Optic Coefficients dno/dT = - 9.3 x 10-6/°C
dne/dT = -16.6 x 10-6/°C
Sellmeier Equations: no2(l) = 2.7359+0.01878/(l2-0.01822)-0.01354 l 2
ne2(l) = 2.3753+0.01224/(l2-0.01667)-0.01516 l 2

The OPO and OPA of BBO are powerful tools for generating a widely tunable coherent radiation from the UV to IR. The tuning angles of type I and type II BBO OPO and OPA have been calculated, with the results shown in below figures.

opo tuning curves of bbo

An OPO output ranging from 680nm to 2400nm with the peak power of 1.6MW and up to 30% energy conversion efficiency was obtained in a 7.2mm long type I BBO. The input pump energy was 40mJ at 532nm with pulse-width 75ps. With a longer crystal, higher conversion efficiency is expected.

In the case of Nd:YAG pumping, BBO's OPOs can generate more than 100mJ, with wavelength tunable from 400nm to 2000nm. By Honor’s BBO nonlinear crystal, the OPO system covers a tuning range from 400nm to 3100nm which guarantees a maximum of 30% and more than 18% conversion efficiency, over the wavelength range from 430nm to 2000nm.

Type II BBO can be used to decrease linewidth near the degenerate points. A linewidth as narrow as 0.05nm and usable conversion efficiency of 12% were obtained. However, a longer (> 15mm) BBO should normally be used to decrease the oscillation threshold when employing the type II phase-matching scheme.

Pumping with a picosecond Nd:YAG at 355 nm, a narrow-band (< 0.3nm), high energy (>200μJ) and wide tunable (400nm to 2000nm) pulse has been produced by BBO's OPAs. This OPA can reach as high as more than 50% conversion efficiency, and therefore is superior to common Dye lasers in many respects, including efficiency, tunable range, maintenance, and easiness in design and operation. Furthermore, coherent radiation from 205 nm to 3500 nm can be also generated by BBO's OPO or OPA plus a BBO for SHG.

A tunable OPO with signal wavelengths between 422nm and 477nm has been generated by angle tuning in a type I BBO crystal pumped with a XeCl excimer laser at 308 nm. And a BBO's OPO pumped by the fourth harmonic of a Nd:YAG laser (at 266nm) has been observed to cover the whole range of output wavelengths 330nm - 1370nm.
When pumped by a 1mJ, 80fs Dye laser at 615nm, the OPA with two BBO crystals yields more than 50μJ (maximum 130μJ), < 200 fs ultrashort pulse, over 800nm - 2000nm.

Custom BBO nonlinear crystal can also be used for E-O applications. It has a wide transmission range from UV to about 3500nm. And it has much higher damage threshold than KD*P or LiNbO3. More than 80W output power and 50KHz repetition rate have been reached by using Honour's E-O BBO crystals and Nd:YVO4 crystals as gain media. At 5KHz, its pulse has a width as short as 6.4ns, and energy of 5.7 mJ or peak power of 900KW. It has advantages over the commercial A-O Q-switched one, including a very short pulse, high beam quality, and size compact as well. Although it has a relative small electro-optic coefficient, and its half-wave voltage is high (7KV at 1064nm, 3x3x20mm3), long and thin BBO can reduce the voltage requirements. Honour Optics now can supply 25mm long and 1mm thin high optical quality of BBO crystal with Z-cut, AR-coated and Gold/Chrome plated on the side faces.

Honour Optics provides the following BBO coatings

Dual Band AR-coating (DBAR) of BBO for SHG of 1064nm; low reflectance (R<0.2% at 1064nm and R<0.5% at 532nm ); high damage threshold (>300MW/cm2 at both wavelengths); Long durability.
Broad Band AR-coating (BBAR) of BBO for SHG of tunable lasers.
Broad Band P-coating of BBO for OPO applications.
Other coatings are available upon request.

Standard Specifications of BBO crystal:

Dimension Tolerance----------------(W±0.05mm)x(H±0.05mm)x(L+/-0.1mm)
Angle Tolerance----------------------△θ< 0.25°,△Φ < 0.25°
Clear Aperture-----------------------central 95% of the diameter
Surface Flatness--------------------<λ/10 at 633nm
Wavefront Distortion---------------<λ/10 @ 633nm
Surface Quality (S/D)---------------10 /5
Parallelism----------------------------< 10 arc seconds
Perpendicularity---------------------< 5 arc minutes
Coatings: Protective (P) and Anti-reflection (AR) coating available upon customer’s requests
Damage threshold------------------>1 GW/cm2 for 1064nm,TEM00, 10ns, 10HZ(polished only)
>0.5 GW/cm2 for 1064nm,TEM00, 10ns, 10HZ(AR-coated)
>0.3 GW/cm2 for 532nm,T EM00, 10ns, 10HZ(AR-coatd)

We can customize crystal angle and size except for standard specification according to your request. It is available to re-polishing and coating for BBO crystals that you supply to us. Welcome everyone to wholesale BBO nonlinear crystal

Standard Applications of BBO crystal:

Second, third, fourth and fifth harmonic generation of Nd:YAG and Nd:YLF lasers
Frequency-doubling, -tripling and -mixing of Dye Lasers
Second, third and fourth harmonic generation of Ti:Sapphire and Alexandrite lasers
Optical parametric amplifier (OPA) and optical parametric oscillators (OPO)
Frequency-doubling of Argon ion, Cu-vapor and Ruby lasers.

Honour Optics offers standard BBO crystals within 4-5 weeks.

1. Harmonic generations of Nd:YAG lasers:
1064nm SHG --> 532nm: 4x4x7mm Type I, θ=22.8°, φ=0°;
1064nm THG --> 355nm: 4x4x7mm Type I, θ=31.3°, φ=0°; Type II q=38.6°, φ=30°
1064nm 4HG --> 266nm: 4x4x7mm Type I, θ=47.6°, φ=0°;
1064nm 5HG --> 213nm: 4x4x7mm Type I, θ=51.1°, φ=0°;

2.OPO and OPA pumped by harmonics of Nd:YAG lasers
532nm Pump --> 680-2600nm: 8x6x12mm Type I, θ=21°, φ=0°;
355nm Pump --> 410-2600nm: 8x6x12mm Type I, θ=30°, φ=0°; Type II, q=37°, φ=30°;
266nm Pump --> 295-2600nm: 8x6x12mm Type I, θ=39°, φ=0°;

3. Frequency doubling of dye lasers
670-530nm SHG --> 335-260nm: 8x4x7mm Type I, θ=40°, φ=0°;
600-440nm SHG --> 300-220nm: 8x4x7mm Type I, θ=55°, φ=0°;
444-410nm SHG --> 222-205nm: 8x4x7mm Type I, θ=80°, φ=0°;

4. Harmonic generations of Ti:Sapphire lasers
700-1000nm SHG --> 350-500nm: 5x5x0.2mm Type I, θ=28°, φ=0°;
700-1000nm THG --> 240-330nm: 5x5x0.2mm Type I, θ=42°, φ=0°;
700-1000nm FHG --> 210-240nm: 5x5x0.2mm Type I, θ=66°, φ=0°;

5. Frequency doubling and tripling of alexandrite lasers
720-800nm SHG --> 360-400nm: 6x4x7mm Type I, θ=31°, φ=0°;
720-800nm THG --> 240-265nm: 6x4x7mm Type I, θ=48°, φ=0°;

6. Intracavity SHG of Ar+laser with Brewster angle-cut BBO Crystal
514nm SHG --> 257nm: 4x4x7mm Type I, θ=51°, φ=0°, B-cut;
488nm SHG --> 244nm: 4x4x7mm Type I, θ=55°, φ=0°, B-cut;

Honour Optics supplies and fabricates high quality BBO crystal, size, and coating upon on your request. Honour Optics is the professional purchasing large size BBO nonlinear crystal manufacturer, buy low-cost BBO nonlinear crystal at factory price.

Please be noted:

BBO has a low susceptibility to the moisture. Users are advised to provide dry conditions for both application and preservation of BBO.
BBO is relatively soft and therefore requires precautions to protect its polished surfaces.
When angle adjusting is necessary, please keep in mind that the acceptance angle of BBO is small.