Lithium Niobate Crystal Series

Magnesium Oxide Doped Lithium Niobate (MgO:LiNbO₃)

Pure Lithium Niobate (LiNbO₃)

AOTK 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"  & Dia. 4" SAW wafers are available with high volume and at low price.

Basic Properties

1. Structual and Physical Properties

Crystal Structure	Trigonal, point group 3m
Lattice Parameters	a = 5.148Å, c = 13.863Å
Density	4.64 g/cm3
Mohs Hardness	5
Melting Point	1250°C
Curie Point	1160°C
Thermal Expansion Coefficient	α1=α2x10-6/°C,α3 = 2.2x10-6/°C at 25°C
Thermal Conductivity	38 W/m/K at 25°C
Elastic Stiffness Constant	CE11 = 2.04 x 1011 N/m2, CE33 = 2.46 x 1011 N/m2
Piezoelectric Strain Constant	d22 = 2.04 x 10-11 C/N, d33 = 19.22 x 10-11 C/N
Dielectric Constant	ε11/ε0 = 85, ε33/ε0 = 29.5
Absorption Coefficient	~ 0.1%/cm @1064 nm

2. Linear Optical Properties

Transparency Region	420-5200nm
Refractive Indexes at 1300 nm at 1064 nm at 632.8 nm	ne = 2.146,  no = 2.220 ne = 2.156,  no = 2.320 ne = 2.203,  no = 2.286
Sellmeier Equations (λ in μm)	no2 = 4.9048+0.11768/(λ2-0.0475)-0.027169λ2 ne2 = 4.5820+0.099169/(λ2-0.04443)-0.02195λ2
Optical Homogeneity	~ 5 x 10-5/cm

3. Nonlinear Optical Properties

NLO Coefficients	d33 = 34.4pm/v d31 = d15 = 5.95 pm/v d22 = 3.07 pm/v
Effective 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 ~45.0 x d36 (KDP) for quasi-phase-matched structure
Electro-Optic Coefficients	γT33  = 32 pm/V,  γ S33 = 31 pm/V γT31 = 10 pm/V,  γS31 = 8.6 pm/V γT22 = 6.8 pm/V, γS22 = 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
Optical Damage Threshold	> 200MW/cm2 (@ 1064nm, 10ns, 10Hz)

Main Applications

I. Applications for Q-switch Elements

LiNbO₃ is 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, the light propagates in Z-axis and electric field applies to X-axis, the refractive retardation will be G = pLn₀³¡₂₂ V/ld. MgO:LiNbO₃ and ZnO: LiNbO₃ crystals have similar electro-optic properties to LiNbO₃ but with higher damage threshold. The specifications of LiNbO₃ Q-Switch Elements listed as the following table:

Standard Specifications

Standard Dimension	9x9x25 or 10x10x20mm3
Dimensional Tolerance	(W ± 0.1mm) x (H ± 0.1mm) x (L +0.2/-0.1 mm)
Wavefront Distortion	< λ/4 @633 nm
Angle Tolerance	Δθ < ± 0.2°, ΔΦ < ± 0.2°
Flatness	λ/8 @633 nm
Surface Quality	10/5 Scratch/Dig per MIL-O-13830A
Parallelism	< 20 arc seconds
Perpendicularity	< 5 arc minutes
Clear Aperture	> 90% central area
AR Coating	R < 0.2% @1064nm per surface
Electrodes	Au or Cr electrode on both X-, surfaces
Quality Warranty Period	one year under proper use

II. Surface Acoustic Wave (SAW) Devices

LiNbO₃ crystal is widely applied as an excellent acousto-optic material for surface acoustic wave (SAW) devices (such as filters, oscillators and resonators) and ultrasonic transducer due to its high electro-mechanical coupling factor, low acoustic transmission loss, stable physical and chemical properties.

AOTK , supplie, s large quanti, ties of LiNbO₃ b, oules, as-cut or finished Φ, 3" and Φ4" wafers available up to 20,000 pieces per month with good quality and very low price.

Typical Applications of piezoelectronic LiNbO3  ● Surface Acoustic Wave (SAW) Device   ● Bulk Acoustic Wave (BAW) Device  ● Leaky Surface Acoustic Wave (LBAW) Device  ● Piezoelectric Transducer  (PET)  ● Piezoelectric Sensor  (PES)

Typical Properties of Piezoelectric LiNbO₃

Orientation	127.86° Y-cut	Y-cut
SAW Velocity	3970 m/s	3485 m/s
Electromechanical Coupling Factor	Ks2 = 5.5%	Ks2 = 4.3%
Temperature Coefficients of Delay (TCD)	78 x 10-6/°C	95 x 10-6/°C
Temperature Coefficients of Velocity (TCV)	-60 x 10-6/°C	-80 x 10-6/°C

Specifications of LiNbO₃ SAW Wafer

Type Specifications	Boule		Wafer
Diameter	Φ3"	Φ4"	Φ3"	Φ4"
Length or Thickness (mm)	≤100	≤50	0.35-1.0
Orientation	127.86°Y, 64°Y, 135°Y, X, Y, Z, and other cut
Ref. Flat Orientation	X,  Y
Ref. Flat Length	22±2mm	32±2mm	22±2mm	32±2mm
Front Side Polishing			Mirror polished 5-15 Å
Back Side Lapping			0.3-1.0 μm
Flatness (μm)			< 15
Bow (μm)			< 25

Note 
 ● Other dimension is also available upon request. 
 ● Wafers are packaged in plastic containers (25 pieces wafers each).


III. Waveguide Substrate

Specifications of LiNbO₃ Waveguide Substrates

Standard Dimension	1) 50x50x1 mm3 for X-cut, Y-cut, or Z-cut 2) Φ3"x1 mm3 for Y-cut or Z-cut 3) Other dimension is available upon request
Orientation Tolerance	< 10'
Surfaces Finish	One surface polished to better than l/2 (with mount) and free from surface defects when observed by a 50X microscope, the other face fine

Magnesium Oxide Doped Lithium Niobate (MgO:LiNbO₃)

MgO:LiNbO₃ crystal 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. But it has the advantages such as high damage threshold (over 300MW/cm² @ 1064 nm, 12ns), noncritical phase matching (NCPM) at room temperature, excellent E-O and NLO properties, good mechanical and chemical properties compared with pure LiNbO₃. 

Its Sellmeier equations (7 mol% MgO doping) are: 
  n_o² = 4.8762+0.115540/(λ²-0.04674)-0.033119λ² (λ in μm) 
  n_e² = 4.5469+0.094779/(λ²-0.04439)-0.026721λ²
Over 45% and 60% of SHG efficient are obtained in pulsed and cw Nd:YAG lasers respectively, by angle tuned phase matchable SHG of Nd:YAG laser (1064 nm) and NCPM SHG of laser lasers (1053 nm) of MgO:LiNbO₃ at room temperature. MgO:LiNbO₃ is also a good crystal for high power quasi-phase-matched waveguide structure for doubler, optical parametric oscillator (OPO) and amplifier (OPA).

AOTK supplies the typical sizes of MgO:LiNbO₃ crystals - 5x5x(20-30) mm³ for OPO and frequency doubler, (20-25)x(20-25)x1 mm³ for waveguide substrates. Other sizes and AR or HR-coatings are available upon request.


Iron Doped Lithium Niobate (Fe:LiNbO₃)

Fe:LiNbO₃ is a excellent photorefractive crystal wth high electro-optic coefficients, high photorefractive sensitivity and diffraction efficiency without applied electric field. Therefore, Fe:LiNbO₃ crystal will find the suitable applications in phase conjugation and holographic recording. High quality Fe:LiNbO₃ crystal, with size as large as Φ3" and iron doped concentrations from 0.01 to 0.1 atm%, could be supplied by AOTK. Some special fabrications are also available to meet customers' requirements.

Magnesium Oxide Doped Lithium Niobate (MgO:LiNbO₃)

MgO:LiNbO₃ crystal 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. But it has the advantages such as high damage threshold (over 300MW/cm² @ 1064 nm, 12ns), noncritical phase matching (NCPM) at room temperature, excellent E-O and NLO properties, good mechanical and chemical properties compared with pure LiNbO₃. 

Its Sellmeier equations (7 mol% MgO doping) are: 
  n_o² = 4.8762+0.115540/(λ²-0.04674)-0.033119λ² (λ in μm) 
  n_e² = 4.5469+0.094779/(λ²-0.04439)-0.026721λ²
Over 45% and 60% of SHG efficient are obtained in pulsed and cw Nd:YAG lasers respectively, by angle tuned phase matchable SHG of Nd:YAG laser (1064 nm) and NCPM SHG of laser lasers (1053 nm) of MgO:LiNbO₃ at room temperature. MgO:LiNbO₃ is also a good crystal for high power quasi-phase-matched waveguide structure for doubler, optical parametric oscillator (OPO) and amplifier (OPA).

AOTK supplies the typical sizes of MgO:LiNbO₃ crystals - 5x5x(20-30) mm³ for OPO and frequency doubler, (20-25)x(20-25)x1 mm³ for waveguide substrates. Other sizes and AR or HR-coatings are available upon request.

Note
 ● Please refer to LiNbO₃ crystal for Properties.