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Yttrium Vanadate (YVO4) Crystal

Birefringent Crystal YVO4 -------- For optical applications

Yttrium orthovanadate (YVO2) is a positive uniaxial crystal with tetragonal structure. It is becoming a very important birefringent material used in communication field. YVO2 can work in fiber optical isolator, beam displacer, circulator and etc. It has started to replace other birefringent crystals in the area because of its wide transparency range and large birefringence. In addition YVO4 has idea mechanical and physical properties which offer good opportunity for lowing down fabrication cost in large scale production. The following table is a comparison of some major birefringent crystals. Many advantages we may find out for YVO4 from this comparison:

Comparison of Some Birefringent Crystals

Crystal

Birefr-

ingence

dn at l 0.63 m

Refractive index

h at l 0.63 m

Thermal optical

Coef.

dh/dT

10-6/K

Structure

and lattice constant,

Melting

point

oC

Density

g/ cm3

Hardness (Mohs)

Thermal

Coef.

10-6/K

Growth Method and

Max. size

TiO2

-0.282

ho=2.583

he=2.865

a: -0.72

c: -0.42

Tetragonal

a=4.593 c=2.958

1840

4.26 7

7

a: 7.14

b: 9.19

Vernuil

f25 x 50mm

YVO4

-0.222

ho=1.9929

he=2.2154

a: -8.5

c: -3.0

Tetragonal a=7.12,

c= 6.29

1825

4.22

5

a: 4.46

b: 11.37

CZ

f38 x 50mm

CaCO3

0.1705

ho =1.6557

he =1.4852

  

Rhomb.

a= 4.989

c= 17.062

1339

2.715

3

a:24.39

b: 5.68

Nature

f1.5" x 50mm

LiNbO3

0.086

ho =2.286

he =2.203

a: 0.53

c: 5.60

Hexagonal

a=5.15

c= 13.86

1255

4.64

5

a: 16.7

c: 2.0

CZ

f75 x 50mm

  • Although rutile ( TiO2 ) has nice birefringence property, it appears to be a rather hard material with hardness Mohs 7. This makes it difficult to be handled in optical polishing. Generally speaking, Vernuil crystal growth method also gives difficulty in getting homogeneous optical crystals.

  • Calcite ( CaCO3 ) has poor mechanical and physical properties. Furthermore its temperature stability and moisture susceptibility are also very bad. A good method for man-made calcite is still in question.

  • The mechanical and physical properties for LiNbO3 are compared to YVO4, but its birefringence is three times lower than YVO4.

In a whole, we can see that YVO4 is the best optical birefringent crystal so far we have known. The following is some related properties for YVO4 in its optical applications:

Crystal Class: Positive uniaxial with no=na=nb, ne=nc

Refractive Indices, Birefringence ( Dn = ne - no) and Walk-off Angle (r) at 45°:

no = 1.9929, ne = 2.2154, Dn = 0.2225, r= 6.04° at 0.63 mm

no = 1.9500, ne = 2.1554, Dn = 0.2054, r = 5.72° at 1.30 mm

no = 1.9447, ne = 2.1486, Dn = 0.2039, r= 5.69° at 1.55 mm

Sellmeier Equation (l in mm):

no 2 = 3.77834 + 0.069736/(l2 - 0.04724) - 0.0108133l2

ne 2 = 4.59905 + 0.110534/(l2 - 0.04813) - 0.0122676l2

Czochraski method has been found to be the best way so far for growing consistent high quality and large size YVO4 crystals. We supply as grown boule, as-cut block and finished crystal parts of Czochraski grown YVO4 . If you have any need for birefringent YVO4 crystals, please feel free to contact us. The highest quality and lowest price are our commitments.

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