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α-BBO,
high temperature phase of BaB2O4,
is an excellent birefringent crystal, which has
been successfully grown in our laboratory. It is characterized
by large birefringent coefficient and wide transmission-window
ranged from 189nm to 3500nm. The high chemical stability
and medium hardness of
α-BBO
make it easy to be fabricated into many kinds of fine optical
components, such as prisms, optical isolators. Therefore,
in many cases, the calcite, YVO4, TiO2
etc. can be replaced by α-BBO.
Especially, compared with natural calcite crystal, whose practical
applications are often limited due to its optical in-homogeneity,
small size and cleavability, α-BBO
has high optical quality and large size (in diameter of 40-50mm
and length of 25-35mm).
|
 |
| Specifications
of α-BBO |
| Diameter |
max
40~50mm |
| Length |
max
25~35mm |
|
Surface
Quality |
20/10
Scratch and Dig |
|
Beam
Deviation |
<3
arc min. |
|
Optical
Axis Orientation |
+/-0.5°
|
|
Flatness
|
λ/4 @
632.8 nm |
|
Transmission
Wavefront Distortion |
<λ/2
@632.8 nm |
|
AR-coating
|
R<0.5%
|
|
|
Basic
Properties of α-BBO
|
| Transparency
Range: 189 - 3500 nm, See Transparency Curve |
Transparency
Curve of
α-BBO
|
| Density:
3.85 g/cm3 |
Therm-Optic
Coefficients:
dno/dT = -9.3 x 10-6/ ℃
dne/dT = -6.6 x 10-6/ ℃ |
Damage
Threshold:
at 1064nm 1GW/cm2
at 355nm 500 MW/cm2 |
| Optical
Homogeneity: Δn ≈10-6/cm |
| Mohs
Hardness: 4.5 |
| Hygroscopic
Susceptibility: Low |
| Thermal
Expansion Coefficients (in the range of 25 ℃– 900
℃):
αa=
4 x 10-6/K, αc= 36 x 10-6/K |
|
Linear
Absorption Coefficients: α <0.005
cm-1 from 300nm to 2300nm |
Refractive
Indices, Birefringence (Δn = ne - no)
and Walk-off Angle at 45º (ρ):
at 1064μm ne= 1.58462, no = 1.65790
Δn =-0.073282 ρ =-4.9532º
at 532nm ne = 1.60206, no
= 1.67755 Δn =-0.075491
ρ =-5.0407º
at 266nm ne = 1.67190, no
= 1.76171 Δn=-0.089805 ρ =-5.6926º
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