Tm doped crystals embrace several attractive features that nominate them as the material of choice for solid-state laser sources with emission wavelength tunable around 2um. It was demonstrated that Tm:YAG laser can be tuned from 1.91 up to 2.15um. Similarly,Tm:YAP laser can tuning range from 1.85 to 2.03 um.The quasi-three level system of Tm:doped crystals requires appropriate pumping geometry and good heat extraction from the active media.On the other hand,Tm doped materials benefit from a long fluorescence life time,which is attractive for high-energy Q-Switched operation.Also,the efficient cross-relaxation with neighbouring Tm3+ ions produces two excitation photons in upper laser level for one absorbed pump photon.This makes the laser very efficient with quantum efficiency approaching two and reduces thermal loading.
Tm:YAG and Tm:YAP found their application in medical lasers, radars and atmospheric sensing.
Properties of Tm:YAP depends on crystals orientation.Crystals cut along the 'a' or 'b' axis are mostly used.
Advantages of Tm:YAP Crysta:
Higher efficiency at 2μm range compared to Tm:YAG
Linearly polarized output beam
Wide absorption band of 4nm compared to Tm:YAG
More accessible to 795nm with AlGaAs diode than the adsorption peak of Tm:YAG at 785nm
Basic Properties:
Space group | D162h (Pnma) |
Lattice constants(Å) | a=5.307,b=7.355,c=5.176 |
Melting point(℃) | 1850±30 |
Melting point(℃) | 0.11 |
Thermal expansion(10-6·K-1) | 4.3//a,10.8//b,9.5//c |
Density(g/cm-3) | 4.3//a,10.8//b,9.5//c |
Refractive index | 1.943//a,1.952//b,1.929//cat 0.589 mm |
Hardness(Mohs scale) | 8.5-9 |
Specifications:
Dopant conenteation | Tm: 0.2~15at% |
Orientation | within 5° |
“avefront distortion | <0.125A/inch@632.8nm |
7od sizes | diameter 2~10mm, Length 2~100mm Jpon request of customer |
Dimensional tolerances | Diameter +0.00/-0.05mm, Length: ± 0.5mm |
Barrel finish | Ground or polished |
Parallelism | ≤10″ |
Perpendicularity | ≤5′ |
Flatness | ≤λ/8@632.8nm |
surface Quality | L0-5(MIL-0-13830B) |
Chamfer | 3.15 ±0.05 mm |
AR Coating Reflectivity | < 0.25% |