The chemical formula of Nd: YAP is Nd3+: YAlO3, and the structure is distorted perovskite, belonging to oblique hexagonal crystal system, and spatial group is Pbnm, whose axes a, b and c are perpendicular to each other, belongs to negative uniaxial crystals and is anisotropic. Among the numerous neodymium-doped laser crystals, Nd: YAP crystal not only has high thermal conductivity, but also has a larger excited emission cross section at 4F3/2–4 I13/2 transition. They are one of the most effective laser crystals known at present for the high-power operation at the 1.3 mm, the crystal is mainly pumped by LD. 1.3 mm lasers are widely used in the field of medicine, optical fiber communication and military. What’ s more, water molecule has good absorption at this laser band. Which makes it have a very good hemostatic ability, and widely used in laser therapy, such as hemostasis, neurosurgery, resection of pathological tissues and wrinkle removal. In addition, Nd: YAP crystal has natural birefringence characteristics, which is very beneficial to overcome the thermal depolarization and nonlinear frequency transformation of laser.
Physical and Chemical Properties
| Crystal Structure | orthorhombic – Pbnm |
| Lattice Constants | a=5,176, b=5,307, c=7,355 |
| Density | 5,35 g/cm3 |
| Melting Point | 1870°C |
| Thermal Conductivity | 0,11 W/(cm K) |
| Thermal Optical Coefficient(dn/dT) | na:9.7×10-6 K-1 nc:14.5×10-6 K-1 |
| Thermal Expansion/(10-6·K-1@25°C) | 9.5 (a axis), 4.3(b axis), 10.8(c axis) |
| Hardness (Mohs) | 8.5 |
| Shear Modulus /Gpa | 2.2×1012 dyn/cm2 |
| Specific Heat | 400 J/(kg K) |
| Linear dispersion δn/δT [10-6K-1] | 9.7 (na) |
Optical and Spectral Properties
| Laser Transition | 4F3/2→4I9/2 930 nm 4F3/2→4I11/2 1079 nm |
| 4F3/2→4I13/2 1340 nm 4F3/2→4I13/2 1432 nm | |
| Laser Wavelength | 930nm 1079nm 1340nm |
| Fluorescence Lifetime | 170ms |
| Refractive index @1064 nm | na=1,929, nb=1,943, nc=1,952 |
Absorption and Emission Spectrum
Material and Specifications
| Materials | Nd: YAP |
| Orientation | <5° |
| Parallelism | ≤10″ |
| Perpendicularity | ≤5′ |
| Surface Quality | 10-5 (MIL-O-13830A) |
| Wavefront Distortion | λ/8 @ 633nm |
| Surface Flatness | ≤ λ/10 @632.8nm |
| Clear Aperture | >95 % |
| Length tolerance | +0.5/-0mm |
| Thickness/Diameter Tolerance | ±0.05 mm |
| Damage Threshold | ≥500MW/cm2 |
Emission Cross Section
| Wavelength (nm) | Emission Cross Section 10-19cm2 | ||
| a-cut | b-cut | c-cut | |
| 1079 | 2.05 | 1.76 | 1.38 |
| 1340 | 1.13 | 0.97 | 0.78 |
| 1432 | 0.34 | ||
High thermal conductivity
Large excited emission cross section
High laser gain
Low laser threshold
Anisotropy