Lithium Niobate（LiNbO3）, exhibits the following excellent properties: high electro-optic and nonlinear optic coefficients, a wide transparency range, high electro-mechanical coupling coefficients, and first-class chemical and mechanical stability. As a well-developed optical material, LiNbO3 has long been widely used for surfaced acoustic devices, integrated optic devices, and new wavelength generation and refractive elements. Similar to YVO4, It has also been a key optical parts for optical fiber isolator.
Introduction of Lithium Niobate
Physical Properties
| Crystal structure | Trigonal crystal system, space group R3c, point group 3m |
| Lattice parameters | a=5.148 Å , c=13.863 Å |
| melting point | 1255℃ |
| Curie temperature | 1140℃ |
| Mohs hardness | 5 |
| Density | 4.64g/cm3 |
| Coefficient of elastic stiffness | CE11 =2.33(×1011N/m2
CE33 =2.77(×1011N/m2 |
Optical Properties
| Light transmission range | 420-5200nm |
| Optical Homogeneity | ~ 5 x 10-5/cm |
| Refractive index at 1064nm | 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 |
| Nonlinear Optical Coefficients (pm/V) | d33=34.4, d31=d15=5.95, d22=3.07 |
| Electro-optic coefficient | γT33 = 32 pm/V, γS33 ;= 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 | 3.03 KV
4.02 KV |
| Damage threshold | 100 MW/cm2 (10 ns, 1064nm) |
Thermal and Electrical Properties
| melting point | 1255 ℃ |
| Curie temperature | 1140 ℃ |
| thermal conductivity | 38W/m/K @25 ℃ |
| Coefficient of Thermal Expansion (@25℃) | //a, 2.0×10-6/K
//c, 2.2×10-6/K |
| Resistivity | 2×10-6 Ω·cm @200 ℃ |
| Dielectric constant | εS11/ε0 =43 εT11/ε0=78
εS33/ε0 =28 εT33/ε0= 32 |
| piezoelectric constant | D22=2.04(×10-11C/N )
D33=19.22 (×10-11 C/N ) |
Sellmeier equation (λ in μm):
no2=4.9048+0.11768/(λ2-0.04750)-0.027169λ2
ne2=4.5820+0.099169/(λ2-0.04443)-0.02195λ2
Applications: LiNbO3 Wedge and Plate
Due to the above suitable optical, physical and mechanical properties, Wedge, Plate or Compensatory Plate, made by LiNbO3 crystals have long been a key component of fiber optical isolators and other devices.
Compared with YVO4 crystal, LiNbO3 enjoys additional cost-effective advantage.
Photonchina provides 50,000 to 100,000 pieces of LiNbO3 wedge per month and has been top tier supplier in China market for such optical crystal parts.
- Fast delivery;
- Strict quality control;
- Technical support;
- Competitive price
LiNbO3 Wedge
| Standard Size | 1.25mm*1.25mm*0.5mm, θ=13°or 15°,φ=22.5° |
| Size Tolerance | +/-0.05mm |
| Wedge Tolerance | +/-0.1° |
| Axis | +/-0.1° |
| Flatness | λ/4 @ 632.8 nm |
| Surface quality | 10-5 |
| Coating | R<0.2% @1550 or 1310nm |
Notes: other specifications are available upon request
LiNbO3 Plate, Compensatory Plate
| Standard Size | 1.25mm*1.25mm*0.7mm,φ=22.5° |
| Size Tolerance | +/-0.02mm |
| Parallelism | <15 min |
| Axis | +/-0.1° |
| Flatness | λ/4 @ 632.8 nm |
| Surface quality | 10-5 |
| Coating | R<0.2% @1550 or 1310nm |
Notes: other specifications are available upon request
Applications: LiNbO3 Q-Switch
Secondly,LiNbO3 from Photonchina is a good choice for electro-optic modulators and Q-switches for Nd:YAG, Nd:YLF and Ti:Sapphire lasers as well as modulators for fiber optics. The following table lists the specifications of a typical LiNbO3 crystal used as Q-switch with transverse E-O modulation. The light propagates in z-axis and electric field applies to x-axis. The electro-optic coefficients of LiNbO3 are: r33 = 32 pm/V, r31 = 10 pm/V, r22 = 6.8 pm/V at low frequency and r33 = 31 pm/V, r31= 8.6 pm/V, r22 = 3.4 pm/V at high electric frequency. The half–wave voltage: Vπ=λd/(2no3r22L), r c=(ne/no)3r33-r13.
LiNbO3 Q-Switch Specifications
| Size | 9 X 9 X 25 mm3 or 4 X 4 X 15 mm3 |
| Other size is available upon request | |
| Tolerance of size | Z-axis: ± 0.2 mm |
| X-axis and Y-axis:±0.1 mm | |
| Chamfer | less than 0.5 mm at 45° |
| Accuracy of orientation | Z-axis: <± 5’ X-axis and Y-axis: < ± 10’ |
| Parallelism | < 20″ |
| Finish | 10/5 scratch/dig |
| Flatness | λ/8 at 633 nm |
| AR-coating | R < 0.2% @ 1064 nm |
| Electrodes | Gold/Chrome plated on X-faces |
| Wavefront distortion | <λ/4 @ 633 nm |
| Extinction ratio | > 400:1 @ 633 nm, φ6 mm beam |
Applications: Acoustic (SAW) Grade LiNbO3 Wafers
Thirdly, LiNbO3 is a good acousto-optic crystal and has been applied in surface acoustic wave (SAW) wafer and A-O modulators. Photonchina provides acoustic (SAW) grade LiNbO3 crystals in wafers, as-cut boules, finished components and custom fabricated elements.
Typical SAW Properties
| Cut Type | SAW Velocity Vs (m/s) |
Electromechanical Coupling Factor k2s (%) |
Temperature Coefficient of Velocity TCV (10-6/oC) |
Temperature Coefficient of Delay TCD (10-6/oC) |
| 127.86o Y-X | 3970 | 5.5 | -60 | 78 |
| Y-X | 3485 | 4.3 | -85 | 95 |
Typical Specifications
| Type Specifications | Boule | Wafer | ||
| Diameter | Φ3″ | Φ4″ | Φ3″ | Φ4″ |
| Length or Thickness(mm) | ≤100 | ≤50 | 0.35-0.5 | |
| 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 mm | |||
| Flatness (mm) | ≤ 15 | |||
| Bow (mm) | ≤ 25 | |||
