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LiNbO3 & MgO:LiNbO3 Crystal

Lithium niobate (LiNbO3) crystal is versatile and well-developed active crystal. They are used as frequency doublers for wavelength > 1 μm and optical parametric oscillators (OPOs) pumped at 1064 nm as well as quasi-phase-matched (QPM) devices, E-O modulator (EOM), A-O modulator(AOM), surface acoustic-wave devices, due to LiNbO3 crystal's large Electro-Optic (E-O) and Acousto-Optic (A-O) coefficients. LiNbO3 also find advanced applications in fluorescence temperature sensing, illumination, domain engineering, memristors, and harvesters.

Properties of LiNbO3 Crystal

Crystal Structure:

Trigonal, space group R3c, Point group 3m

Cell Parameters:

a = 0.5148, c = 13.863, Z = 6

Melting Point:

1253°C

Curie Point:

1140°C

Mohs Hardness:

Density:

4.64 g/cm³

Specific Heat:

0.59 J/g/K

Thermal Conductivity:

38 W /m /K @ 25°C

Thermal Expansion Coefficient(@ 25°C):

//a, 2.0x10^-6 /K; //c, 16.7x10^-6 /K

Optical Homogeneity:

~ 5x10^-5 /cm

Transparency Range:

420 -- 5200 nm

Absorption Coefficient:

~ 0.1%/cm @ 1064 nm

Solubility:

insoluble in water

Relative Dielectric Constant:

ε₁₁/ε₀: 85, ε₃₃/ε₀: 29.5

Thermal Expansion Coefficients:

//a 2.0 x 10^-6 /K , //c 2.2 x 10^-6 /K@25°C

The Sellmeier equations (Pure LN))(λ in µm)

no² = 4.9048+0.11768/(λ²-0.04750)-0.027169λ²
ne² = 4.5820+0.099169/(λ²-0.04443)-0.021950λ²

Refractive indices at 1064 nm(Pure LN):

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

Thermal Optical Coefficient:@1.4 µm

dno/dT=-0.874x10^-6/K, dne/dT=39.073x10-6/K

NLO Coefficients:

(x//m) d11 = -d12 = -d26 = 2.6 pm/V d31 = d32 = d24 = d15 =4.6 pm/V d33 = 25 pm/V

Electro-Optic Coefficient:

(x//m) γT11 = 6.8 pm/V, γs11 = 3.4 pm/V γT13 = 10 pm/V, γs13 = 8.6 pm/V γT33 = 32 pm/V, γs33 = 31 pm/V

Photorefractive Damage Threshold:

50 MW/cm2 (10 ns, 1064 nm)

Surface Damage Threshold:

300 MW/cm2 (10 ns, 1064 nm)

MgO:LiNbO3 Crystal

Compared with LiNbO3 crystal, MgO:LiNbO3 has similar linear and nonlinear optical properties, but the photorefractive damage threshold is much higher. MgO:LiNbO3 crystal exhibits particular advantages for NCPM frequency doubling (SHG) of Nd:Lasers, mixing (SFG) and optical parametric oscillators (OPOs). The SHG efficiencies of over 65% for pulsed Nd:YAG lasers and 45% for CW Nd:YAG lasers have been achieved in MgO:LiNbO3 Crystals respectively. MgO:LiNbO3 is also good for optical parametric oscillators(OPOs) and amplifiers (OPAs), quasi-phase-matched doublers and integrated waveguides.

MgO:LiNbO3 Features:

- High damage threshold

- Noncritical phase matching-NCPM at room temperature

- Broad transparency range

- Excellent E-O and NLO properties

- Good mechanical and chemical properties

MgO:LiNbO3 crystal Sellmeier equations (for 5mo1% MgO dopant, λ in µm):

MgO dopant 5 mol%
n_o² = 4.9017+0.112280/(λ²-0.049656)-0.039636λ²
n_e² = 4.5583+0.091806/(λ²-0.048086)-0.032068λ²

MgO dopant 7 mol%
n_o² = 4.8762 + 0.11554 / ( λ² - 0.04674 ) - 0.033119 λ²
n_e² = 4.5469 + 0.094779 / ( λ² - 0.04439 ) - 0.026721 λ²

Periodically poled lithium niobate(PPLN)

Periodically poled lithium niobate (PPLN) is developed for quasi phase matching of the LiNbO3 crystal. PPLN expanped the functionality of LiNbO3 as OPO and SHG applications. To get stable operation, PPLN is usually put inside a crystal oven with temperature controller, because the inverted (poled) portions of the crystal is sensitive to the temperature changing.

General Specifications

Dimension Tolerance:

+0/-0.1mm(WxH) and +0.1/-0.2mm thickness

Surface Quality:

10-5 Scratch-dig

Flatness:

<λ/8 @633nm

Chamfer:

0.1mm@45deg.

Clear Aperture:

Central 90% of Diameter

Parallelism:

<10 arc seconds

Perpendicular:

<10 arc minutes

Orientation Angle:

+/-0.25deg.

AR coating:

R<0.2%/0.5% Dualband AR or Broadband AR coating R<1%

OptoCity offer LiNbO3, LiTaO3, MgO:LiNbO3 crystal as wafer, waveguide, NLO, E-O components and more. Please contact us for more information.