LiNbO3 (Lithium niobate, LN) crystal is a negative uniaxial crystal and one of the most thoroughly characterized optical materials. With its wide transparency range in the visible and mid-infradred and the excellent chemical and mechanical stability, LN crystal can be used as a bifrengent material for applications in infrared.
Both pure LN and MgO doped LN (MgO:LN) are available from Newlight Photonics.
| Model | Name | aperture | thickness | orientation | Price | Availability | Action |
| LNM8050-A | Pure LN crystal window, Size 8x8x0.5mm, A-cut, both surfaces polished and uncoated | 8x8mm | 0.5mm | a-cut | Ask | ||
| LNM8200-A | Pure LN crystal window, Size 8x8x2.0mm, A-cut, both surfaces polished and uncoated | 8x8mm | 2.0mm | a-cut | Ask | ||
| LN1020-A | Pure LN crystal window, Dia. 1"x2.0mm, A-cut, both surfaces polished and uncoated | Dia 1" | 2.0mm | a-cut | Ask | ||
| LN1020-C | Pure LN crystal window, Dia. 1"x2.0mm, C-cut, both surfaces polished and uncoated | Dia 1" | 2.0mm | c-cut | Ask |
Basic Properties of pure LiNbO3:
| Crystal Structure | Trigonal, Space group R3C, Point group 3m |
| Cell Parameters | a=5.148 Å , c=13.863 Å |
| Melting Point | 1253oC |
| Curie Temperature | 1140oC |
| Mohs Hardness | 5 |
| Density: | 4.64 g/cm3 |
| Deliquescence | None |
| Optical Homogeneity | ~ 5x10-5 /cm |
| Transparency Range | 420 -- 5200 nm |
| Absorption Coefficient | ~0.1%/cm @ 1064 nm |
| Refractive indices at 1064nm (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 Expansion Coefficient (@ 25oC) |
//a, 2.0x10-6/K |
| //c, 16.7x10-6/K | |
| Thermal Conductivity Coefficient: | 38 W/m/K at 250 oC |
| Thermal Optical Coefficient | dno/dT=-0.874x10-6/K at 1.4 µm dne/dT=39.073x10-6/K at 1.4 µm |
| 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 |
MgO doped LiNbO3 (MgO:LN) has similar linear optical properties to pure LiNbO3, but the photorefractive damage threshold is much higher.
The Sellmeier equations of MgO:LN are:
MgO dopant 5 mol%
no2 = 4.9017+0.112280/(λ2-0.049656)-0.039636λ2
ne2 = 4.5583+0.091806/(λ2-0.048086)-0.032068λ2
Common cut orientations:
Coatings:
LN or MgO:LN crystals are uncoated unless the coating is specified. Anti-reflection coatings (AR coatings) with R < 0.25% at the specified wavelengths are available upon request.