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Lithium
Niobate (LiNbO3 or LNB) and Lithium Tantalate (LiTaO3
or LTA) possess a combination of unique electro-optical, acoustic,
piezoelectric, pyroelectric and non-linear optical properties making
it a suitable material for applications in acoustic, electro-optical
and non-linear optical devices, high-temperature acoustic transducers,
receivers-transmitters of acoustic vibrations, air force acceleration
meters, acoustic wave delay lines, deflectors, generators of non-linear
distorted waves, acoustic filters, electro-optical Q-modulators (Q-switch),
encoders-decoders, filters in television receivers, video-recorders
and decoders, converters, frequency doublers and resonators in laser
systems, non-linear elements in parametric light generators, etc. An
indispensable condition of some of these applications is a high degree
of optical uniformity of Lithium Niobate crystals used for fabrication
of active elements. Crystal growth technology by low temperature-gradient
Czochralsky method allows the growth of large-size high-quality LNB
(up to 1-1.5 kg) and LTA single crystals for such non-conventional applications.
It should be noted that both crystals are non-hygroscopic, colourless,
water-insoluble and have low transmission losses.
LiNbO3 damage due to photorefractive effect in congruent
melt grown LiNbO3 certainly limits it's applications in high optical
power devices. For this purpose specially grown LiNbO3 with composition
near stoichiometric can be offered. It is similar to the Li-rich VTE
LiNbO3 with the obvious advantage that bulk samples can be obtained.
Another possibility to increase laser damage threshold of LiNbO3 is
doping with MgO. MolTech can offer both MgO:LiNbO3 and stoichiometric
LiNbO3 elements cut from boules up to 60 mm dia.
Some other crystals of LiNbO3 series are available,
including LiNbO3 doped with Fe, Zn, Gd, Cu , Y, B, Er etc.
For some applications similar in properties to Lithium
Tantalate (LiTaO3) crystal is more advantageous than LiNbO3 (E-O
modulators, pyroelectric sensors etc.). Lithium Tantalate exhibits unique
electro-optical, pyroelectric and piezoelectric properties combined
with good mechanical and chemical stability and wide transparency range
and high optical damage threshold. This makes LiTaO3 well-suited for
numerous applications including electro-optical modulators, pyroelectric
detectors, optical waveguide and SAW substrates, piezoelectric transducers
etc. MolTech can offer parts cut from high quality boules grown along
X axis, fully poled, with dia. and length of up to 60 mm. |
MAIN PROPERTIES:
| Material |
LNB |
LTA |
| Transparency
range, µm |
0.4 - 5 |
0.4 - 5 |
| Point group |
3m |
3m |
| Space group |
R3c |
R3c |
| Lattice
parameters (hexagonal), Å |
a = 5.148,
c = 13.863 |
a = 5.154,
c = 13.784 |
| Density,
g/cm3 |
4.64 |
7.45 |
| Mohs hardness |
5 |
5.5 |
| Refractive
indexes : |
no
= 2.28647, ne = 2.20240 (at 0.633 µm) |
no
= 2.183, ne = 2.188 (at 0.6 µm) |
|
no
= 2.2273, ne = 2.1515 (at 1.1523 µm) |
no
= 2.131, ne = 2.134 (at 1.2 µm) |
| Non-linear
coefficient at 1.06 µm, pm/V |
d22
= 5.6, d31 = -11.6, d33 = 8.6 |
d22
= 2, d31 = -1, d33 = -21 |
| Electroptical
coefficient at 0.63 µm, pm/V |
r31
= 8.6, r22 = 3.4, r33 = 30.8, r51
= 28 |
r13
= 8, r22 = -0.2, r33 = 30 |
MolTech provides
LiNbO3 and LiTaO3 crystals with high optical quality
as finished wafers, elements or blanks at your request. Orientation,
polishing, single-band and dual-band AR-coatings by customers' order.
The AR-coatings are characterized by low reflectance, high damage threshold
and long durability.
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