Sillenite Crystals (BGO/BSO/BTO)
Photorefraction is an effect of refractive
index variation in the material exposed to the light. This property makes
it possible to create spatial distribution of refractive index in the crystal
and can be used in wide variety of devices including spatial light modulators,
optical memory, holography, phase conjugation etc.
Most popular photorefractive materials are crystals of Sillenite structure Bi12MO20
(M = Si, Ge, Ti). These crystals have fortunate combination of photorefractive,
electrooptic and other properties making it promising materials for optoelectronics.
Material propeties
| |
BSO |
BGO |
BTO |
| Crystal symmetry |
Cubic, 23 |
Cubic, 23 |
Cubic, 23 |
| Lattice parameter, A |
10.104 |
10.145 |
10.176 |
| Density, g/cm3 |
9.14 |
9.23 |
9.10 |
| Mohs hardness |
5 |
4.5 |
5 |
| Melting point , °C |
900 |
925 |
840 |
| Transparency range, nm |
0.45 - 6 |
0.45 - 7 |
0.5 - 6 |
| Refractive Index |
2.54 |
2.55 |
2.56 |
| Optical Absorption, cm-1 |
0.3 |
0.2 |
0.5 |
| ElectroopticalCoefficient (r41),pm/V |
5.0 |
3.5 |
5.7 |
| Half-wave Voltage, kV |
3.9 |
5.7 |
3.3 |
| Natural Optical Activity,deg/mm |
22 |
20 |
6.3 |
Dielectric Constant
( low frequency)
|
56 |
40 |
46 |
NOTE
- If not specified, optical properties are given for wavelength 633 nm.
- Finished
elements are available in sizes (3–20)x(3–20)x(3–20) mm3.Wafers with dia.
up to 40 mm, or 30x30 mm square, 0.5 - 5.0 mm thick are available. Orientation:
Standard [110] cut or other on request.
- Polish standard: 20/10 S/D,
λ/4 flatness, parallelism < 2’
- Coatings available:
a) AR @ 514.5 nm, 532 nm or other on request
b) ITO conductive/transparent coatings
c) electrodes Cr + Au
- Other photorefractive crystals available from ELAN:
doped BSO & BTO, Fe:LiNbO3, crystals for UV photorefraction (LiTaO3,
LiIO3,
non-doped LiNbO3 , Bi4Ge3O12,).
- Optical absorption increases under illumination of crystal e.g. by sunlight.
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