BBO Crystals

BBO crystal remains the most versatile nonlinear optical crystals thanks to its unique combination of optical properties (e.g. broad transmission and phase matching ranges, high damage threshold) and availability of large, high quality single crystals. Newlight's BBO crystals have been widely used in second, third, fourth or fifth harmonic generations for high power visible/UV sources, and optical parametric conversions for high power broadly tunable sources.

BBO products on this page are thick crystals (> 3 mm) for applications with picosecond (ps), nanosecond (ns), or long pulse/CW lasers.

For thin/ultrathin BBO products (thickness: 0.01 mm - 3 mm) developed for frequency conversions of ultrafast femtosecond (fs) lasers, please visit thin/ultrathin BBO crystals.

For BBO products (including paired BBO crystals) developed for spontaneous down conversions (SPDC), please visit SPDC components.

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Model	Name	application	wavelength	thickness	Price	Availability	Action
BBO4050-SHG1064(I)-AR	BBO crystal with size 4x4x5.0mm, AR coating @ 1064/532nm, for Type I SHG of λ centred @ 1064 nm	SHG (I)	1064nm	5.0mm	USD$659.00	Out Of Stock
BBO4070-SHG1064(I)-AR	BBO crystal with size 4x4x7mm, AR coating @ 1064/532nm, for Type I SHG of λ centred @ 1064 nm, mounted	SHG (I)	1064nm		USD$699.00
BBO4100-SHG1064(I)-AR	BBO crystal with size 4x4x10mm, AR coating @ 1064/532nm, for Type I SHG of λ centred @ 1064 nm	SHG (I)	1064nm		USD$849.00
BBO4050-THG1064(I)-AR	BBO crystal with size 4x4x5mm, AR coating @ 1064/532/355nm, for Type I SFG of λ centred @ 1064nm and λ/2 centred @ 532nm to obtain λ/3 (THG of 1064nm)	THG (I)	1064nm		USD$659.00
BBO4050-THG1064(II)-AR	BBO crystal with size 4x4x5mm, AR coating @ 1064/532/355nm, for Type II SFG of λ centred @ 1064nm and λ/2 centred @ 532nm to obtain λ/3 (THG of 1064nm)	THG (II)	1064nm		USD$659.00
BBO4070-THG1064(I)-AR	BBO crystal with size 4x4x7mm, AR coating @ 1064/532/355nm, for Type I SFG of λ centred @ 1064nm and λ/2 centred @ 532nm to obtain λ/3 (THG of 1064nm)	THG (I)	1064nm		USD$699.00
BBO4070-THG1064(II)-AR	BBO crystal with size 4x4x7mm, AR coating @ 1064/532/355nm, for Type II SFG of λ centred @ 1064nm and λ/2 centred @ 532nm to obtain λ/3 (THG of 1064nm)	THG (II)	1064nm		USD$699.00
BBO4050-SHG532(I)-AR	BBO crystal with size 4x4x5mm, AR coating @532/266nm, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm)	SHG (I)	532nm	5.0mm	USD$609.00
BBO4070-SHG532(I)-AR	BBO crystal with size 4x4x7mm, AR coating @532/266nm, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm), mounted	SHG (I)	532nm	7.0mm	USD$699.00	2-3 Days
BBO4100-SHG532(I)-AR	BBO SHG device, crystal size 4x4x10mm, AR coating @532/266nm, designed for Type I SHG of λ @ 532 nm (4HG of 1064nm)	SHG (I)	532nm	10.0mm	USD$849.00	Out Of Stock
BBO6015-SHG532(I)-AR	BBO crystal with size 6x6x1.5mm, AR coating @532/266nm, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm), mounted in OD 1" anodized aluminum holder	SHG (I)	532nm	1.5mm	Ask
BBO8080-SHG532(I)-AR	BBO crystal with size 8x8x8.0mm, AR coating @532/266nm, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm)	SHG (I)	532nm	8.0mm	Ask
BBO3070-SHG532(I)-P	BBO crystal with size 3x3x7mm, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm), P-coating, mounted in OD 1" holder	SHG (I)	532nm	0	Ask
BBO4070-SHG532(I)-B	BBO crystal with size 4x4x7mm, two ends Brewster cut, for Type I SHG of λ centred @ 532 nm (4HG of 1064nm)	SHG (I)	532nm	0	Ask
BBO4070-SHG515(I)-AR	BBO crystal with size 4x4x7mm, AR coating @515/257nm, for Type I SHG of λ centred @ 515 nm (4HG of 1030nm)	SHG (I)	515nm	7.0mm	USD$699.00	Out Of Stock

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Newlight BBO features,

Broad phase-matching range from 410 nm to 2100 nm

Useful optical transmission from 190 nm to 3500 nm

Large effective second-harmonic-generation (SHG) coefficient about 6 times greater than that of KDP crystal

High damage threshold of 10 GW/cm² for 100ps pulse-width at 1064 nm

High optical homogeneity with δn ~ 10^-6/cm

Wide temperature-bandwidth of about 55 ^oC

Low thermo-optic coefficient

Structural and Physical Properties:

Crystal Structure	Trigonal, Space group R3c, Point group 3m
Cell Parameters	a = b = 12.532 Å, c = 12.717Å, Z = 6
Melting Point	1095°C
Transition Temperature	925°C
Mohs Hardness	4
Density	3.85 g/cm³
Specific Heat	1.91 J/cm³ x K
Hygroscopic Susceptibility	Low
Thermal Expansion Coefficients	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

Linear Optical Properties:

Transparency Range	189-3500 nm
Optical Homogeneity	δn ~ 10^-6/cm
Absorption Coefficient	< 0.1%/cm (at 1064 nm)
Sellmeier Equations (λ in µm)	n_o²=2.7359+0.01878/(λ²-0.01822)-0.01354λ² n_e²=2.3753+0.01224/(λ²-0.01667)-0.01516λ²
Refractive Indices at 1064 nm at 800 nm at 532 nm at 400 nm at 266 nm	n_o = 1.6545, n_e = 1.5392 n_o = 1.6606, n_e = 1.5444 n_o = 1.6742, n_e = 1.5547 n_o = 1.6930, n_e = 1.5679 n_o = 1.7585, n_e = 1.6126
Thermo-optic Coefficients	dn_o/dT = -9.3 x 10^-6/°C dn_e/dT = -16.6 x 10^-6/°C

Nonlinear Optical Properties:

Phase-matchable SH Wavelengths:	189 - 1750 nm
NLO Coefficients	d₁₁ = 5.8 x d₃₆(KDP) d₃₁ = 0.05 x d₁₁ d₂₂ < 0.05 x d₁₁
Effective Nonlinearity Expressions	d_ooe= d₃₁ sinθ +(d₁₁ cos3φ - d₂₂ sin3φ) cosθ d_eoe= (d₁₁ sin3φ + d₂₂ cos3φ) cos2θ
Electro-optic Coefficients	γ₁₁ = 2.7 pm/V, γ₂₂, γ₃₁ < 0.1 γ₁₁
Half-wave Voltage	48 kV (at 1064 nm)
Damage Threshold (Bulk) at 1064 nm at 532 nm	5 GW/cm² (10 ns); 10 GW/cm² (1.3 ns) 1 GW/cm² (10 ns); 7 GW/cm² (250 ps)

Application Examples:

BBO is of particular importance in the visible and far UV. A wide variety of phase-matching applications are possible, including the following:

Second, third, fourth and fifth harmonic generation of Nd doping lasers

Second harmonic generation to generate wavelengths as short as 204.8 nm

Shorter wavelengths (193 nm) can be generated by sum frequency mixing

Frequency doubling, tripling and -mixing of Dye lasers

Second, third and fourth harmonic generation of Ti:Sapphire lasers

Optical parametric amplifier (OPA) and optical parametric oscillators (OPO)

Frequency-doubling of Argon ion, Cu-vapor and Ruby lasers

Pockel cells for high average power or short wavelength applications

SHG and SFG

BBO is the only NLO material which can be used to produce the fifth harmonic generation (5HG) of Nd:YAG lasers at 213 nm. Because of a small acceptance angle and large angular walkoff, good laser beam quality (small divergence, good mode condition, etc.) is the key for BBO to obtain high conversion efficiency. Tight focus of laser beam is not recommended.

NLO properties for harmonic generations with Type I PM in BBO crystal
Harmonics	SHG	THG	4HG	5HG
Effective NLO Coefficient( x d₃₆(KDP) )	5.3	4.9	3.8	3.4
Acceptance Angle (mrad-cm)	1.0	0.5	0.3	0.2
Walk-off Angle (°)	3.2	4.1	4.9	5.5

OPO and OPA

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 following, respectively.


Type I OPO Tuning Curves	Type II OPO Tuning Curves

Ultrafast Laser (Ti:sapphire)

Frequency doubling and tripling of ultrashort lasers are the applications in which BBO shows superior properties to KDP or ADP crystal. BBO crystals as thin as 0.01 mm (10 µm ) for these purposes are available. A laser pulse as short as 10 fs can be efficiently frequency doubled with an ultrathin BBO crystal with the minimal group-velocity matching.

Specifications of BBO components:

Wavefront Distortion:	< λ/8 @ 633 nm for Aperture =< 5mm, L =< 5mm
Dimension Tolerance:	(W+/-0.1 mm) x (H+/-0.1 mm) x (L+0.2/-0.1 mm)
Clear Aperture:	> 90% central area
Flatness:	λ/8 @ 633 nm
Surface Quality:	Scratch/Dig 10/5 per MIL-O-13830A
Parallelism:	better than 20 arc seconds
Perpendicularity:	5 arc minutes
Angle Tolerance:	Δθ < 0.25o, Δφ < 0.25o

Coatings:

1. Protective coating (P-coating): This is a single-layer MgF2 coating protecting a polished surface of BBO crystal from fogging due to ambient moisture. It also partially reduces reflection from the polished surface at a certain wavelength range.

Coating curve: P-coating (typical).

2. Anti-reflective coatings (AR coatings): These are multi-layer dielectric coatings. Single-band, dual-band or broad-band AR coatings on BBO surfaces are available upon request.

Coating curves: AR532/266 nm, AR1064/532 nm, AR800/400 nm, AR710/355 nm (typical).

Mounts:

For customer convenience the crystals can be mounted in an 1" anodized aluminum (Al) mount. The mounted crystals can be further mounted in a conventional 1" mirror mount to be angle tuned for phase matching (as shown to the right). Water-cooled mounts for high power applications can be offered upon request.

BBO Crystal Handling:

BBO has a low susceptibility to moisture. The AR coating or the protective coating (P-coating) on the crystal faces can protect the faces from moisture to some extent. It is fine to leave the crystal in the setup for most optics labs with RH =< 40%. However, we suggest to store the crystal in a desiccator if it will not be used for over > 2 weeks to prolong the crystal lifetime. Alternatively, a small enclosure (with openings for light) may be built around the crystal with a continuous flow of dry nitrogen of air into the enclosure. The dry nitrogen/air pressure needs only to be slightly above the atmosphere to keep the small volume around the crystal dry and clean.

BBO is relatively soft and therefore requires precautions to protect the surfaces.

Cleaning Crystals:

Dust and stains on crystal surfaces can cause scattering/loss of light and can even react with light to damage optical surfaces at a high incident laser power.

Inspect the crystal surface for dust and stains by holding it near a bright visible-light source. Viewing at different angles can help see scattering from dust and stains. The crystal surface has to be cleaned as described below if dust and stains are found.

Note: Perform the following cleaning procedures in a clean, low-dust environment while wearing powder-free gloves or ﬁnger cots.

1. Blowing off the crystal surface

Use a canister of compressed N2/clean air or a blower bulb (e.g., http://www.adorama.com/GTRABS.html ) to blow off dust and other loose contaminants first. If a dry nitrogen line is available in the lab, an air gun can also be used to blow away dust particles. Blow off the surface gently. Do not blow off the crystal itself from your hand!

2. Drop and Drag Method

Hold the crystal so that the crystal surface is horizontal and slightly above your fingers. Take a fresh, clean sheet of lens tissue and place it on the crystal. Make sure the lens tissue can be drawn across the crystal surface. Next, place a small drop of pure isopropyl alcohol (IPA) on the lens tissue on top of the crystal surface. The weight of the solvent will cause the lens tissue to come into contact with the crystal surface. Slowly but steadily drag the damp lens tissue across the crystal surface being careful not to lift the lens tissue off of the surface. Continue dragging the lens tissue until it is off of the surface.

The amount of the solvent can be adjusted for various crystal size so the lens tissue is kept damp for the entire drag but there is not any visible trace of solvent on the crystal surface after the drag is finished. Inspect the surface and repeat if necessary, but only use each sheet of lens tissue once.

If the crystal surfaces are still “dirty” after the above cleaning procedures, the surfaces might have been damaged. Please contact us for rework of the crystals.