BBO(beta-BaB2O4 ) is grown with the flux method. It is a negative uniaxial crystal, with ordinary refractive-index larger than extraordinary refractive-index. Also, it is a nonlinear optical crystal with combination of number of unique features. Wide transparency and phase matching ranges, large nonlinear coefficient, high damage threshold and excellent optical homogeneity provide attractive possibilities for various nonlinear optical applications. BBO has the following exceptional properties that make it a very important nonlinear crystal:
Useful optical transmission from 190 nm to 3500 nm
Broad phase-matching range from 410 nm to 2100 nm
Large effective second-harmonic-generation (SHG) coefficient about 6 times greater than that of KDP crystal
High damage threshold of 10GW/cm2 for 100ps pulse-width at 1064nm
Low thermo-optic coefficient
 

1)BBO Wedges:

Speicfications: Material: ..................................................BBO(β-BaB2O4) Orientation: ....................................................0.3 degree S/D: ..........................................................................10-5 Flatness:...........................................................Lambda/4 Wavefront Distortion: ....................................Lambda/10

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Part No.	A(mm)	B(mm)	H(mm)	Theta(mm)	Phi (mm)	Wed.(mm)
BBO 101	5.0	8.0	3.0	27°	30°	20'
BBO 102	4.0	4.0	7.0	31°	0°	5'
BBO 103	12.0	12.0	2.0	47°	0°	5'
BBO 104	14.0	8.0	21.0	36°	30°	2°
BBO 105	12.0	6.5	21.0	36°	30°	2°
Note: Other sizes and specifications are available upon request.

 

Physical and Optical Properties
Crystal Structure: ............................................................trigonal, space group R3c
Cell Parameters :............................................ a = b = 12.532Å, c = 12.717Å, Z = 6
Melting Point: ....................................................................................1095 +/-5 °C;
Transition Temperature:.......................................................................925 +/-5 °C; 
Optical Homogeneity: ..................................................................................10-6 /cm
Mohs Hardness: ..................................................................................................4.5 
Density: ..................................................................................................3.85 g/cm3
Absorption Coefficient: .......................................................< 0.1%/cm (at 1064 nm)
Hygroscopic Susceptibility: ..................................................................................low
Resistivity:........................................................................................ > 1011 ohm-cm
Relative Dielectric Constant: .......e T 11 / e 0 : 6.7, e T 33 /e 0 : 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 
Phase-matchable SHG range: ......................................................... 205nm-1750nm 
NLO coefficients:..... d 11 = 5.8 x d36(KDP)  d 11 = 0.05 x d 11 , d 22 < 0.05 x d 11  
Electro-Optic Coefficients: ...........................g 11 = 2.7 pm/V, g 22 , g 31 < 0.1 g 11 
Half-Wave Voltage: ...................................................................48 KV (at 1064 nm) 
Damage Threshold at 1.064 mm at 0.532 mm:
.....5 GW/cm 2(10 ns); 10 GW/cm 2(1.3 ns)1 GW/cm 2(10 ns); 7 GW/cm 2(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: dn o /dT= - 9.3 x 10 -6/°C; dn e /dT =-16.6 x 10 -6 /°C;
Sellmeier Equations: n o 2 ( l ) = 2.7359+0.01878/( l 2 -0.01822)-0.01354 l 2
n e 2 ( l ) = 2.3753+0.01224/( l 2 -0.01667)-0.01516 l 2

 

Capabilities
1)Aperture: ......................................................................................1x1 ~ 12x12mm
2)Length: ..............................................................................................0.02 ~ 25mm
3)Phase matching angle θ and φ: Determined by different kinds of homonic generartion.
4)Phase matching type: ..................................................................Type I or Type II
5)End configuration:......................................................Flat or Brewster or Specified

 

Typical Specification and Tolerance
1)Angle tolerance: ...........................................................Δθ < ± 0.5°; Δφ < ± 0.5°
2)Dimension tolerance: ............(W ± 0.1mm) x (H ± 0.1mm) x (L + 0.2mm/-0.1mm)
3)Flatness:....................................................................................... < λ/8 @ 633nm
4)Scratch/Dig code: ........................better than 10/5 Scracth/dig per MIL-O-13830A
5)Parallelism: .................................................................................< 20 arc seconds
6)Perpendicularity:.............................................................................<5 arc minutes
7)Wavefront distortion: ....................................................................< λ/8 @ 633nm
8)Clear aperture:........................................................................> 90% central area
9)Coating:........................................................Protective Coating or Anti-Reflection

 

Notes:

To inquiry or order a finished BBO crystals, please specify the specifications listed above. For the nonlinear crystals, the maximum conversion efficiency is mostly determined by three specification crystals length, phase matching type, and phase matching angles(θ and φ).

As a result of large thermal acceptance bandwidth, high damage threshold and small absorption BBO well suits for frequency conversion of high peak or average power laser radiation.The large spectral transmission range as well as phase matchability, especially in UV range, makes BBO perfectly suitable for frequency doubling of Dye, Ar+-ion and Copper vapour laser radiation, effective cascade harmonic generation of wide spread Nd:YAG as well as of Ti:Sapphire and Alexandrite laser radiation. Both angle tuned Type 1 (oo-e) and Type 2 (eo-e) of phase matching can be obtained increasing a number of advantages for different applications.SHG phase matching angle dependence on input radiation wavelength is shown in Fig. 1.

 

Both Type 1 and Type 2 phase matching are used in OPO devices based on BBO crystals and designed for pump at different harmonics (up to fifth) of Nd:YAG lasers. Type 1 of interaction gives a larger tuning range and higher parametric amplification rate comparing to type 2 of interaction, while using type 2 interaction you are obtaining narrower bandwidth of output as shown in Fig.2. Parametric gain in BBO is about10 times higher then in KDP in case of 355 nm pump for type 1 interaction. Up to 30% energy conversion efficiency has been obtained using BBO crystal of 12 mm length in OPO device synchronously pumped at 532 nm, which outputs at 640-3170 nm. Because of small acceptance angle and?large walk off, the use of input laser radiation with good beam quality and low divergence is required for efficient conversion.

 

 

The crystals with different angle cut for various applications are listed as follows:

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

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

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

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

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

6) Intracavity SHG of Ar+ laser with brewster angle cut BBO
514nm SHG --> 257nm: 4x4x7mm Type I, q =51°, f =0°, B-cut;
488nm SHG --> 244nm: 4x4x7mm Type I, q =55°, f =0°, B-cut;

Mounting:

In order to prevent crystals from damaging or to be easily operated, Dayoptics provide three kinds of mount of holder to install different dimension crystals. Please contact our sales for more information.