22 May 2019 Description
LiNbO3 crystal has been widely used in optical waveguide and optical communication technology because of its excellent electro-optical properties. It is an ideal substrate material for many integrated optoelectronic devices. Because of the large electro-optic coefficient of LiNbO3, the half-wave voltage is low. The electro-optic effect of LiNbO3 crystal is usually used to modulate the optical signal. Electro-optic modulation is divided into longitudinal and transverse, and LiNbO3 is mainly used in transverse modulation. It has been widely used in medium and low power solid-state lasers.
Parameter
Physical and optical properties
Chemical formula |
LiNbO3 |
Crystal structure |
trigonal |
Space group |
R3C |
Density |
4.64 g/cm3 |
Mohs hardness |
5 |
Optical homogeneity |
~ 5 x 10-5 / cm |
Transparency range |
420 – 5200 nm |
Absorption coefficient |
~ 0.1 % / cm @ 1064 nm |
Refractive indices at 1064 nm |
ne = 2.146, no = 2.220 @ 1300 nm |
ne = 2.156, no = 2.232 @ 1064 nm |
ne = 2.203, no = 2.286 @ 632.8 nm |
Sellmeier equations (λ, μm) |
no2 = 4.9048 + 0.11768 / (λ2 – 0.04750) – 0.027169λ2 |
ne2 = 4.5820 + 0.099169 / (λ2 – 0.04443) – 0.021950λ2 |
Thermal expansion coefficient @ 25 °C |
//a, 2.0 x 10-6 / K |
//c, 2.2 x 10-6 / K |
Thermal conductivity |
~ 5 W/m/K @ 25 °C |
Thermal optical coefficient |
dno/dT = -0.874 x 10-6 / K at 1.4 µm |
dne/dT = 39.073 x 10-6 / K at 1.4 µm |
LiNbO3 General specification for Q-Switch
Refractive retardation |
Γ=лLnr22V/λd |
Electro-optic coefficients |
R33=32pm/V |
R31=10pm/V |
R22=6.8 pm/V |
Aperture |
4x4mm ~ 9x9mm |
Length |
15~25mm |
Tolerance of size |
+/-0.1mm |
Chamfer |
|
Accuracy of orientation |
|
Parallelism |
|
Flatness |
l/8 at 632.8 nm |
Wavefront Distortion |
<l/4 at 632.8 nm |
Extinction Ratio |
>400:1 @ 633nm, dia 6mm beam |
LiNbO3 specification for Optical waveguide
Operating wavelength range |
1.525-1.605μm |
Extinction ratio |
<20dB |
Half wave voltage |
<6V |
DC bias voltage |
<8V |
Input characteristic impedance |
50Ω |
Light reflection |
≤-50dB |
Maximum input electric power |
20dBm |
Maximum input optical power |
10-100mW |
Storage temperature |
-40-85℃ |
Operating temperature |
-40-70℃ |
piezoelectric property
Elastic stiffness coefficient cij/(1010N/m2) |
c11 |
c12 |
c13 |
c14 |
c33 |
c44 |
20.3 |
5.3 |
7.5 |
0.9 |
24.5 |
6.0 |
Elastic compliance coefficient sij/(10-12m2/N) |
S11 |
S12 |
S13 |
S14 |
S33 |
S44 |
5.78 |
-1.01 |
-1.47 |
-1.02 |
5.02 |
17.0 |
piezoelectric strain constant dij/(10-11C/N) |
d11 |
d15 |
d22 |
d31 |
d33 |
|
8 |
7.4 |
2.04 |
-0.086 |
1.62 |
|
dielectric constant |
εT11/ε0 |
εT11/ε0 |
|
|
|
|
78 |
32 |
|
|
|
|
Electromechanical coupling coefficient kij(%) |
k15 |
k31 |
|
|
|
|
68 |
50 |
|
|
|
|
Nonlinear Optical Properties
NLO Coefficients |
d33 = 34.4 pm/V |
d31 = d15 = 5.95 pm/V |
d22 = 3.07 pm/V |
Efficiency NLO Coefficients |
deff =5.7 pm/V or ~14.6 x d36 (KDP) for frequency doubling 1300 nm; |
deff =5.3 pm/V or ~13.6 x d36 (KDP) for OPO pumped at 1064 nm; |
deff =17.6 pm/V or ~45 x d36 (KDP) for quasi-phase-matched structure. |
Electro-Optic Coefficients |
gT33 = 32 pm/V, gS33 = 31 pm/V, |
gT31 =10 pm/V, gS31=8.6 pm/V, |
gT22 = 6.8 pm/V, gS22= 3.4 pm/V, |
Half-Wave Voltage, DC Electrical field||z, light ^z: Electrical field||x or y, light||z: |
3.03 KV |
4.02 KV |
|
|
Damage Threshold |
100 MW/cm2 (10 ns, 1064nm) |
Standard Specifications of laser grade LiNbO3 crystals
Transmitted wavefront distortion |
better than l/4 @ 633nm |
Dimension tolerance |
(W±0.1mm) x (H±0.1mm) x (L±0.2mm) |
Clear aperture |
over 90% central diameter |
Flatness |
l/8 @ 633nm |
Surface quality |
20 /10 Scratch/Dig |
Parallelism |
better than 20 arc sec |
Perpendicularity |
5 arc min |
Angle tolerance |
Dq < 0.5o, Df < 0.5o |
AR-coating |
dual wave band AR coating at 1064/532 nm on both surfaces, with R < 0.2% at 1064 nm and R < 0.5% at 0.532 nm per surface |
Features
-
wide transparency range
-
High electro-optic efficiency
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Stable mechanical and chemical properties
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Low absorption loss
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low damage threshold
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Small volume
-
Not easy to deliquesce
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High temperature stability
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Large electro-optic coefficient
-
Easy to grow into large crystal
Applications
Optical Communication
Holography
Medical Applications
Pulse range finder
Laser target indicator
Electro-optic Q-switch |