Lithium Niobate Crystal

LiNbO3 Crystal is widely used as frequency doublers for wavelength > 1mm and optical parametric oscillators (OPOs) pumped at 1064 nm as well as quasi-phase-matched (QPM) devices. Due to its large Electro-Optic (E-O) and Acousto-Optic (A-O) coefficients, LiNbO3 crystal is the most commonly used material for Pockel Cells, Q-switches and phase modulators, waveguide substrate, and surface acoustic wave (SAW) wafers, etc.

AZURE provides high quality and large size LiNbO3 crystals for laser frequency doublers, OPOs and quasi-phase-matched doublers, as well as waveguide substrate and SAW wafers. High quality LiNbO3 components with aperture of (2 - 15) x (2 - 15) mm2 and length up to 50 mm for frequency doublers and optical parametric oscillators (OPOs), 50x50x1 mm3 or Dia. 3" x 1 mm LiNbO3 substrate for waveguide optics, and Dia. 3" SAW wafers are available with high volume and at low price.
SPECIFICATIONS

1. Basic Properties

Crystal Structure

Trigonal, space group R3c

Cell Parameters

a = 0.515, c = 13.863, Z = 6

Melting Point

1255±5oC

Curie Point

1140±5oC

Mohs Hardness

5

Density

4.64 g/cm3

Absorption Coefficient

~ 0.1%/cm @ 1064 nm

Solubility:

insoluble in H2O

Relative Dielectric Constant

eT11/e0: 85
eT33/e0: 29.5

Thermal Expansion Coefficients( @ 25oC)

||a, 2.0 x 10-6/K ||c, 2.2 x 10-6/K

Thermal Conductivity

38 W /m /K @ 25oC

2. Linear Optical Properties

Transparency Range
420-5200nm

LiNbO3 Transparency Curve

Refractive Indices
ne=2.146, no = 2.220 @ 1300 nm
ne= 2.156, no = 2.232 @ 1064 nm
ne= 2.203, no = 2.286 @ 632.8nm

Optical Homogeneity ~ 5 x 10-5 /cm

Sellmeier Equations (l in mm):

n2o (l) = 4.9048+0.11768/(l2 - 0.04750) - 0.027169l2

n2e (l) = 4.5820+0.099169/(l2 - 0.04443) - 0.021950l2

3. 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)

4. 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

  • Magnesium Oxide Doped Lithium Niobate Crystals (MgO:LiNbO3)


Compared with LiNbO3 crystal, MgO:LiNbO3 crystal exhibits its 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 a good crystal for optical parametric oscillators (OPOs) and amplifiers (OPAs), quasi-phase-matched doublers and integrated waveguide.

MgO:LiNbO3 has similar effective nonlinear coefficients to pure LiNbO3. Its Sellmeier equations (for MgO dopant 7 mol%) are:

n2o (l) = 4.8762+0.11554/(l2 - 0.04674) - 0.033119 x l2 (l in um)

n2o (l) = 4.5469+0.094779/(l2 - 0.04439) - 0.026721 x l2 

AZURE provides high quality MgO:LiNbO3 crystals for various nonlinear optics (NLO) and E-O applications. The typical size of MgO:LiNbO3 crystals is (3 - 10) x (3 - 10) x (10 - 30) mm3 for OPOs & OPAs and frequency doubling & mixing, and 20x20x1 mm3 for waveguide substrates. Other specs. and AR-coatings for MgO:LiNbO3 are available upon request.


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