Birefringent Crystals

Birefringent Crystals

Birefringent Crystals

FOCtek provide a wide range of birefringent crystals: YVO4, Calcite, ?-BBO, LiNbO3, quartz, etc. The crystals are widely used in the application of beam displacers, polarizing optics (Glan Laser, Glan Taylor, Glan Thompson, Wollaston and Rochon), optical isolators, circulators and interleaver, etc.

The comparation of refractive indices, birefringence, and walk off anlge for common crystals are listed below for reference.(Notes: ? is walk off angle at crystal 45o cut)

YVO4

1550nm:

no=1.9447

ne=2.1486

Dn=0.2039

r=5.69o

Calcite:

1550nm:

no=1.6629

ne=1.47722

Dn=-0.1564

r=-5.75o

a-BBO

1550nm:

no=1.64998

ne=1.51199

Dn=-0.137996

r=-4.99o

LiNbO3

1550nm:

no=2.21122

ne=2.13806

Dn=-0.073156

r=-1.93o


Feature comparation of YVO4, Calcite, a-BBO Birefringent crsytals
1) YVO4 has better temperature stability and physical and mechnical properties than others.
2) Calcite is hard to obtain high optical quality because of its low susceptibility to moisture and low
hardness, which make it easily scratched.
3) LiNbO3 birefringence is smallest among them, although its mechanical and physical properties is similar
to YVO4.
4) ?-BBO transparency range can cover far UV wavelength band from 189nm to 3500nm, it's especially
Suitable for high power and UV polarizer application.

The main properties is listed follows

 

YVO4

Calcite

a-BBO

Transparency

400—5000nm

350—2300nm

189—3500nm

Crystal class(Uniaxial)

Positive

no=na=nb,ne=nc

Negative

no=na=nb,ne=nc

Negative

no=na=nb,ne=nc

Mohs hardness

5

3

4.5

Thermal Expansion Coefficient

a a=4.43x10-6/k

a c=11.37x10-6/k

a a=24.39x10-6/k

a c=5.68x10-6/k

a a=4x10-6/k

a c=36x10-6/k

Hygroscopic susceptibility

Non-Hygroscopic

Low to moisture

low