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  • 名称: BBO
  • 编号: 115
  • 上传时间: 2014-08-01
  • 浏览次数: 245

BBO (Beta-Barium Borate or β-BaB2O4)is an outstanding nonlinear optical crystal which has the obvious and unique advantages on frequency conversions of high peak power laser radiation from UV to VIS.

 

BBO is grown with the flux method. It is a negative uniaxial crystal, with ordinary refractive-index (no) larger than extraordinary refractive-index (ne).  Both type I and type II phase-matching can be reached by angle-tuning.

 

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

BBO has susceptibility to moisture. The user is advised to provide dry conditions for both working and storage of BBO.

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

When angle adjusting is necessary, keep in mind that the acceptance angle of BBO is small.

Main Applications:

SHG, THG, 4HG, 5HG of Nd lasers

SHG, THG, 4HG of Ti:Al2O3 and Alexandrite lasers

SHG, THG and Frequency-mixing of Dye lasers

SHG of Argon ion, Cu-vapor and Ruby lasers

OPA and OPO

Electro-Optical application (Pockels Cell)

SHG and SFG

Because of a small acceptance angle and large walk-off, 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. BBO is the only NLO material which can be used to produce the fifth harmonic generation (5HG) of Nd:YAG lasers at 213 nm.

Relevant NLO properties for type I BBO crystal

 Fundamental wavelength: 1064nm

SHG

THG

FHG

5HG

Effective NLO Coefficient  (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

 

BBO is a negative uniaxial crystal with ordinary refractive-index(no) larger than extraordinary refractive-index(ne). Both type I and type II phase-matching can be reached by angle-tuning. The phase matching angles of frequency doubling are shown in following figure.

 

Ultrafast Pulse (Ti:sapphire) Laser

Frequency-doubling and -tripling of ultrashort-pulse lasers are the applications in which BBO shows superior properties. As thin as 0.02mm BBO for this purpose is available.. A laser pulse as short as 10 fs can be efficiently frequency-doubled with a thin BBO, in terms of both phase-velocity and group-velocity matching.

 

BBO's 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 are shown in following figure, respectively.

  

 

BBO`s E-O Applications

 

BBO can also be used for E-O applications. It has wide transmission range from UV to about 3500nm and it has much higher damage threshold than KD*P and LiNbO3. It has many advantages, including a very short pulse, good beam quality and compact size. Although it has a relative small electro-optic coefficient, the Half-wave voltage is high (7KV at 1064nm,3*3*20mm3), long and thin BBO can reduce the voltage requirements. CRYSTECH can supply 25mm long high quality BBO crystal with Z-cut, AR-coated and Gold plated on the side faces.

Main Features:

Wide transmission region

Broad PM SHG range

Large effective SHG coefficient

High damage threshold

Wide temperature-bandwidth

High optical homogeneity

 

Dimension Tolerance

W(+/-0.1)*H(+/-0.1)*L(+0.5/-0.1)mm

Angle Tolerance

+/-0.25°

Perpendicularity

≤ 10’

Scratch/Dig

20/10

Chamfer

≤ 0.2mm x 45°

Parallelism

10″

Chips

≤ 0.1mm

Flatness

λ[email protected]

Clear Aperture

≥ 90%

Wavefront distortion

λ[email protected]

Coatings

C1---   [email protected](R<0.2%)&266(R<0.5%)

C2---   [email protected](R<0.2%)&532(R<0.5%)&355(R<0.5%)

C3---   Pcoating/Pcoating

Damage Threshold

1GW/cm² (1064nm, 10ns, 10Hz)

 

 

P/N

Cut  Angle

Size(mm)

Coating

Application

BBO-X-447-C1

Θ=47.7°φ=0°

4x4x7

[email protected]&266nm

[email protected]

BBO-X-557-C1

Θ=47.7°φ=0°

5x5x7

[email protected]&266nm

[email protected]

BBO-X-667-C1

Θ=47.7°φ=0°

6x6x7

[email protected]&266nm

[email protected]

BBO-Y-447-C2

Θ=31.3°φ=0°

4x4x7

[email protected]&532&355nm

[email protected]

BBO-Y-557-C2

Θ=31.3°φ=0°

5x5x7

[email protected]&532&355nm

[email protected]

BBO-Y-667-C2

Θ=31.3°φ=0°

6x6x7

[email protected]&532&355nm

[email protected]

BBO-Z-55005-C3

Θ=29.2°φ=0°

5x5x0.05

Pcoating/Pcoating

[email protected]

BBO-Z-5505-C3

Θ=29.2°φ=0°

5x5x0.5

Pcoating/Pcoating

[email protected]

BBO-Z-551-C3

Θ=29.2°φ=0°

5x5x1

Pcoating/Pcoating

[email protected]

BBO-Z-66005-C3

Θ=29.2°φ=0°

6x6x0.05

Pcoating/Pcoating

[email protected]

BBO-Z-6605-C3

Θ=29.2°φ=0°

6x6x0.5

Pcoating/Pcoating

[email protected]

BBO-Z-661-C3

Θ=29.2°φ=0°

6x6x1

Pcoating/Pcoating

[email protected]

BBO-Z-1010005-C3

Θ=29.2°φ=0°

10x10x0.05

Pcoating/Pcoating

[email protected]

BBO-Z-101005-C3

Θ=29.2°φ=0°

10x10x0.5

Pcoating/Pcoating

[email protected]

BBO-Z-10101-C3

Θ=29.2°φ=0°

10x10x1

Pcoating/Pcoating

[email protected]

 

Physical properties:

Crystal Structure:

Trigonal, space group R3c

Lattics Parameters:

a=b=12.532Å, c=12.717Å, Z=6

Melting point

About 1095

Mohs Hardness

4

Density

3.85g/cm3

Thermal Conductivity

1.2W/m/K(c): 1.6W/m/K(//c)

Thermal Expansion Coefficients

11=4x10-6/K; 33=36x10-6/K

 

Optical Properties:

 

Transparency Range:

190-3500nm

SHG Phase Matchable Range

409.6-3500nm(Type I)    525-3500nm(Type II)

therm-optic Coefficients(/)

dno/dT=-16.6x10-6

dne/dT=-9.3x10-6

Absorption Coefficients

<0.1%/cm at 1064nm         <1%/cm at 532nm

Angle Acceptance

0.8mrad-cm      (θ, Type I,1064 SHG)   
1.27mrad-cm    (θ, Type II,1064 SHG)

Temperature Acceptance

55-cm

Spectral Acceptance

1.1nm-cm

Walk-off Angle

2.7°   (Type I 1064 SHG)
3.2°  (Type II 1064 SHG)

NLO Coefficients

deff (I)=d31sinθ+(d11cosΦ-d22sin3Φ)cosθ
deff (II)=(d11sin3Φ+d22cos3Φ)cos2θ

Non-vanished NLO susceptibilities

d11=5.8xd36(KDP)
d31=0.05xd11
d22<0.05xd11

sellmeier Equations(λ in μm )

no2=2.7359+0.01878 / (λ2-0.01822) -0.01354 λ2
ne2=2.3753+0.01224 / (λ2-0.01667) -0.01516 λ2

Electro-optic coefficients:

r22=2.7pm/V

Half-wave voltage:

7KV (at 1064nm,3*3*20mm3)

Resistivity:

>1011 ohm-cm

Relative Dielectric Constant:

εs11o:6.7
εs33o:8.1
Tan δ<0.001