Almaz Optics, Inc.
12 Chadsford Ct.  Marlton, NJ 08053, USA
Tel:  856 797-0491, Fax: 856 797-0228
e-mail: mail@almazoptics.com

 

































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.

Materials Properties

 

 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

Electrooptic Coefficient (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

1.      If not specified, optical properties are given for wavelength 633 nm.

2.      Finished elements are available in sizes (320)x(320)x(320) mm3. Wafers with diameter up to 40 mm, or 30x30 mm square, 0.5 - 5.0 mm thick are available. Orientation: Standard [110] cut or other on request.

3.      Polish standard: 20/10 S/D, lambda/4 flatness, parallelism < 2

4.      Coatings available:
    a) AR @ 514.5 nm, 532 nm or other on request
    b) ITO conductive/transparent coatings
    c) electrodes Cr + Au

5.      Other available photorefractive crystals:
doped BSO & BTO, Fe:LiNbO3, crystals for UV photorefraction (LiTaO3, LiIO3, non-doped LiNbO3 , Bi4Ge3O12,).

6.      Optical absorption increases under illumination of crystal e.g. by sunlight.