22 May 2019 Description
LGS(La3Ga5SiO14 )is a multifunctional intraocular crystal that can be used as an electro-optic crystal after considering and studying the interaction between electro-optic effect and optical rotation in functional crystals. The LGS electro-optic Q switch passes light along the Z direction of the crystal and applies an electric field along the X direction, which can make full use of the lateral electro-optic effect of the crystal to realize the Q-switch function of the LGS crystal. The electro-optic Q-switch made by LGS is actually a new kind of rotation-electro-optical Q-switch. Because of the effect of optical rotation, it can be used as a practical switch and a good Q-modulation result can be obtained. LGS crystal widens the new direction of exploring and discovering new electro-optic crystals from optically active crystals.
Parameter
Material and Specifications
| Point group |
32 |
| Airborne group |
P32I |
| specific resistance |
4.0×1012Ω/cm-1 |
| Thickness |
0.13-0.5mm |
| Diameter |
50mm |
| Length |
90-100mm |
| Melting point |
1470℃ |
| Density |
5.67g/cm3 |
| Mohs hardness |
5.5 |
| Thermal expansion coefficient |
aa=16×10-6/K, ac=4×10-6/K |
| Photo damage threshold |
670MV/cm2 |
| Cell Parameters |
a=b=0.8162nm,c=0.5087nm |
| Dielectric constant |
ε11=18.27 |
| ε33=55.26 |
| Electro-optical coefficients |
γ11=2.3×10-12m/V |
| γ33=1.8×10-12m/V |
Piezoelectric strain constant
(10-12)C/N |
d11=6.3 |
| d14=-5.4 |
| Phase velocity,m/s |
2750～2850 |
| Electromechanical coupling coefficient, K[ %] |
0.28～0.46 |
| Solubility |
None |
| Coefficient of thermal expansion |
α11=5.15×10-6K-1 |
| α33=3.65×10-6K-1 |
LGS crystal for Q-switch
| Maximum operating frequency |
50KHz |
|
| Maximum output power |
7.5W |
|
| Pulse width |
46ns |
|
| Energy output -40℃ |
155mJ |
|
| Energy output +50℃ |
163mJ |
|
| Room temperature energy output |
167mJ |
|
| Electro-optic conversion efficiency |
1.26% |
Comparative properties of piezoelectric crystals
| Propertie |
|
|
|
|
| Quartz |
LGS |
Li2B4O7 |
LiTaO3 |
| Electromechanical Coupling Factor K, %(BAW) |
7 |
15.8 |
24 |
47 |
| Frequency Spacing Δf, % |
0.25 |
0.9 |
4 |
7 |
| Q-Factor Q, ×103 |
100 |
50 |
10 |
2 |
| Temperature Frequency Coefficient TFC,×10-6/℃ |
0.5 |
1.6 |
6 |
4 |
SAW properties of langasite and Quartz
|
Properties
|
Quartz |
LGS |
| |
|
| Density, g/cm³ |
2.65 |
5.746 |
| SAW Velocity Vef, m/s |
(0°, 132.75°, 0°)
3157
|
(0°, 140°, 25°)
2756
|
| Electromechanical coupling factor K2emc, %(SAW) |
0.14 |
0.36 |
| Second order temp. coef.α2, ×10-8/℃ |
-3.2 |
-6.8 |
| Temp. Coef. TTO, ℃ |
25 |
23 |
| Dielectric Constant e |
4.92 |
27 |
| Power flow angle , ° |
0 |
0.5 |
Dielectric, piezoelectric, elastic stiffness constants and their first order temperature coefficients of langasite crystal
| Constant |
Relative Dielectric Constant |
Piezoelectric Constant （pC/N） |
Elastic Stiffness（1011 Pa） |
| ε11 |
ε33 |
d11 |
d14 |
c11 |
c12 |
c13 |
c14 |
C33 |
C44 |
| Value |
18.96 |
50.19 |
5.66 |
-5.48 |
1.898 |
1.058 |
1.022 |
0.144 |
2.626 |
0.535 |
| First Order Temp. Coef.（10-6·K-1） |
150 |
-760 |
329 |
-342 |
-66 |
204 |
-75 |
-335 |
-94 |
-63 |
Features
-
High damage threshold
-
Good optical rotation
-
Can withstand high and low temperature changes
-
Stable physical and chemical properties
-
High electromechanical coupling coefficient (3 times of quartz)
-
Low equivalent series resistance
Applications
|
