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| 所属类别： |
非线性光学晶体 |
| 商品名称： |
LiNBO3 |
| 浏览次数： |
1517 次 |
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I. Introduction
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Good optical and electrical properties, large size and relative low price make Lithium Niobate (LiNbO3) be one of the most important crystals in the field of optics and electronics. It is widely used in the laser and electronic industry for the following applications: laser components, wafers for surface acoustic wave devices, wafers for integrated optics applications and doped LiNbO3crystals for nonlinear optics (MgO:LiNbO3, ZnO:LiNbO3), photo-refractive effects devices (Fe:LiNbO3), etc. Please refer to the following background data and technical information for versatile applications.
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II. Pure Lithium Niobate (LiNbO3)
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OPO, Frequency and Quasi-Phase-Matched (QPM) Doublers
Due to its specific properties shown as follows, LiNbO3 is commonly used as not only frequency doubler (wavelength > 1 mm) but optical parameter oscillator (OPO) pumped at 1.064 mm, as well quasi-phase-matched (QPM) doubler. Caston optronics supplies laser-grade LiNbO3 devices of (2-18) x (2-18) mm2 aperture and up to 50 mm length for frequency doubler and optical parameter oscillator, with high quality, large quantity and cheap price.
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| Crystal Structure |
Trigonal, 3m-point group |
| Lattice Parameters |
a=b=5.15Å, c=13.863Å, Z=6 |
| Density |
4.64 g/cm3 |
| Melting Point |
1250 oC |
| Curie Point |
~ 1160 oC |
| Mohs Hardness |
~ 5 |
| Relative Dielectric Constant |
e11T/e0 = 85; e33T/e0 = 29.5 |
| Absorption Coefficient |
~ 0.1%/cm@1.064 mm |
| Thermal Conductivity |
38 W/m/oC at 25oC |
| Thermal Expansion Coefficient |
a1=a2 =2x10-6/oC, a3=2.2x-6/ oC at 25oC |
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Optical and NLO Properties
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| Transparency Region |
0.37 mm ~ 5.0 mm |
| Optical Homogeneity |
Dn ~ 5x10-5/cm |
| Nonlinear Coefficients |
deff=13.6 d36(KDP) - OPO @ 1.064 mm |
| deff=14.6 d36(KDP) - SHG @1.30 mm |
| deff=45.0 d36(KDP) - QPM |
| Refractive Indexes |
no |
ne |
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| 2.220 |
2.146 |
at 1.30 mm |
| 2.322 |
2.156 |
at 1.064 mm |
| 2.286 |
2.203 |
at 0.633 mm |
| Sellmeier Equations (l in mm) |
no2 = 4.9048+0.11768/(l2-0.0475)-0.027169l2 |
| ne2 = 4.5820+0.099169/(l2-0.04443)-0.02195l2 |
Electro-optic Coefficients
(X 10-12m/V) |
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Low frequency |
High frequency |
| g33 |
32 |
31 |
| g31 |
10 |
8.6 |
| g22 |
6.8 |
3.4 |
| Damage Threshold |
> 250 KW/ cm2 at 1.064 mm. (10 ns) |
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- Surface Acoustic Wave (SAW) Devices
- LiNbO3 single crystal is also commonly used as an excellent material for surface acoustic wave (SAW) devices (such as filters, oscillators and resonators) and ultrasonic transducer due to its considerably high electro-mechanical coupling factor, low acoustic transmission loss, stable physical and chemical properties. CASTON can supply large quantities of LiNbO3 boules, as-cut or finished f 3" wafers available up to 5,000~ 8,000 pieces per month with good quality and very low price. Please find the following basic specifications for LiNbO3 SAW wafer.
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Specifications of LiNbO3 SAW Wafers
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| Standard Size |
(f 3" ±0.01") x (0.51 ±0.05)mm
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| Orientation |
(1)127.86o Y-cut; (2)YZ-cut;
(3)41o or 64o Y-cut
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| Surface Finish |
one surface mirror polished to Ra less than 10 C, reverse surface fine ground
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| SAW Velocity |
3485m/s (Y-cut), 3970m/s (127.86o Y-cut)
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| Electromechanical Coupling Factor |
K31=0.023, Z00Kt=0.17
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| Temperature Coeff. of Delay (TCD) |
78X10-6/oC (127.86o Y-cut)
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| Temperature Coeff. of Velocity(TCV) |
-60X10-6/oC (127.86oY-cut)
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LiNbO3 is also extensively used as electro-optic modulator and Q-switch for Nd:YAG, Nd:YLF and Ti:Sapphire lasers as well as modulator for fiber optics, etc. The transverse modulation is mostly employed for LiNbO3. If a LiNbO3 crystal is used as Q-switch crystal with specifications listed as the following, the light propagates in Z-axis and electric field applies to X-axis, the refractive retardation will be G =p Lno3g22V/ld. MgO:LiNbO3 and ZnO:LiNbO3 crystals have similar electro-optic properties to LiNbO3 but with higher damage threshold.
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Specifications of LiNbO3 Q-Switch Elements
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| Standard Dimension |
9x9x25 or 10x10x20mm3 (other sizes also available) |
| Dimension Tolerance |
±0.1mm (X; Y-axis); ±0.3mm (Z-axis) |
| Orientation Accuracy |
< 10' (X & Y-axis); < 5' (Z-axis) |
| Wavefront Distortion |
< l /4 @633nm |
| Scratch/Dig Code |
10/5 to MIL-O-13830A |
| Parallelism |
< 10" |
| Flatness |
l /8 @632.8nm |
| Chamfer |
< 0.5 mm at 45o` 5o |
| AR-Coating |
R < 0.2% @1064nm |
| Electrodes |
Gold or Cr electrode on X-faces |
| Extinction Ratio |
> 400:1 @633nm, (f 6mm beam) |
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Waveguide Substrates
For electro-optic waveguide applications, the mostly used inorganic substrate is LiNbO3 crystal.
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Specifications of LiNbO3 Waveguide Substrates
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| Standard Dimension |
(1) 50x50x1 mm3 for X-cut, Y-cut, or Z-cut |
| (2) f 3"x1 mm3 for Y-cut or Z-cut |
| Tolerance of Orientation |
< 10' |
| Surface Finish |
one surface polished to better than l /2 (with mount) and free from surface defects while observed by a 50X microscope, the other face fine ground |
III. Magnesium Oxide Doped Lithium Niobate (MgO:LiNbO3)
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MgO:LiNbO3 crystal has the advantages such as high damage threshold (over 5 GW/cm2 @1.064mm, 12ns), non-critical phase matching (NCPM) at room temperature, broad transparent range, excellent E-O and NLO properties, good mechanical and chemical properties compared with pure LiNbO3. So it is widely used for high power frequency doubling (SHG), mixing (SFG) and optical parameter oscillator (OPO).
MgO:LiNbO3 has similar effective nonlinear coefficients as pure LiNbO3. Its Sellmeier equations (7 mol% MgO doping) are:
| no2 = 4.8762+0.115540/(l2-0.04674)-0.033119l2 |
(l in mm) |
| ne2 = 4.5469+0.094779/(l 2-0.04439)-0.026721l2 |
Angle tuned phase matchable SHG of Nd:YAG laser (1.064 mm) and NCPM SHG of laser lasers (1.053 mm) of MgO:LiNbO3 (high MgO doping) can be achieved at room temperature. Over 45% and 60% of SHG efficient are obtained in pulsed and cw Nd:YAG lasers respectively. MgO:LiNbO3 is also a good crystal for high power quasi-phase-matched waveguide structure for doubler, optical parametric amplifier (OPA) and oscillator (OPO).
The typical sizes of MgO:LiNbO3 crystals provided by caston are 5x5x(20-30) mm3 for OPO and frequency doubler, (20-25)x(20-25)x1 mm3 or f40x1 mm3 for waveguide substrates. Other sizes and AR or HR-coatings are available according to customers' requirements.
IV. Zinc Oxide Doped Lithium Niobate (ZnO:LiNbO3)
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ZnO:LiNbO3 crystal has the advantages as MgO:LiNbO3, high damage threshold, non-critical phase matching (NCPM) at room temperature, good mechanical and chemical properties. Moreover it has better optical homogeneity than MgO:LiNbO3. So it is another excellent candidate for high power frequency doubler, OPO and quasi-phase-matched waveguide structure for doubler.
V. Neodymium and Magnesium Oxide Doped Lithium Niobate (Nd:MgO:LiNbO3)
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Nd:MgO:LiNbO3 is a self-frequency doubling laser crystal, which combines the excellent laser properties of the Nd3+ ion with the electro-optical and NLO properties of LiNbO3. Furthermore, it also remains the advantage of high damage threshold of MgO:LiNbO3. These permit Nd:MgO:LiNbO3 crystal to be designed of miniature green lasers and other miniature muti-functional devices, including self-frequency-doubled lasers, self-modulated and self-Q-switch lasers, and waveguide devices.
Nd:MgO:LiNbO3 crystals with different Nd3+ and MgO doped concentrations based on customers' specific requirements could be supplied by CASTON.
VI. Iron Doped Lithium Niobate (Fe:LiNbO3)
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Fe:LiNbO3 is one kind of excellent photorefractive crystal with high electro-optic coefficients, high photorefractive sensitivity and diffraction efficiency without applied electric field. Therefore, Fe:LiNbO3 crystal will find the niche applications in phase conjugation and holographic recording. High quality Fe:LiNbO3 crystal, with size as large as 3" (Diameter) and iron doped concentrations from 0.01 to 0.1 atm%, can be supplied by CASTON. Special fabrications are also available upon request.
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