Description of Thulium-doped Yttrium Aluminium Garnet Crystal
Tm: YAG operates on the 3H4 → 3H6 transition in a wavelength range of 0.82 µm. It can be pumped with efficient diode lasers in the wavelength range of 0.78–0.8 µm. The transition exhibits a small quantum defect, thereby resulting in minimal thermal load. The upper state lifetimes can reach approximately one millisecond, which permits adequate energy storage. Furthermore, it offers a sufficient amplification bandwidth to support pulses with a duration of less than one second, depending on the host material and operating temperature. Compared with single-crystal materials, the transparent ceramic materials combine the advantages of single crystals and glasses. The transparent ceramic materials are produced by solid-state reaction and vacuum sintering. Consequently, they not only possess favourable optical and thermal properties akin to single crystals but may also be manufactured in large sizes and high concentration. In addition, they require a short fabrication period and incur lower costs.
Advantages of Tm: YAG:
- High quantum efficiency
- High efficiency with LD pump
- Long upper state lifetime
- Adequate amplification bandwidth
- Small quantum defect
- High damage threshold
Specifications of Thulium-doped Yttrium Aluminium Garnet Crystal
Material Specifications
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Tolerance of Tm concentration
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Tm: 0.5~5 at%
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Orientation
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[111], <5°
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Parallelism
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≤10"
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Surface quality
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10-5 (MIL-0-13830A)
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Perpendicularity
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<5'
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Wavefront distortion
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≤ 0.125λ/25 mm @632.8nm
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Surface flatness
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λ/8 @632nm
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Clear aperture
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>95%
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Wedge
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0.15±0.05 mm
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Dimensions
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D: 2~10mm, L: 3~150mm
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Coatings
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AR: ≤0.25% @2µm
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Optical and Spectral Properties
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Laser transition
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3F4 → 3H6
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Laser wavelength
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1.87~2.16µm
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Temperature dependence of refractive index
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7.3×10⁻⁶/K
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Absorption cross-section
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7.5×10⁻²¹ cm²
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Diode pump band
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785nm, 680nm
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Emission cross-section @2013nm
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2.9×10⁻²⁰ cm²
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Fluorescence lifetime
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11ms
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Refractive index @632nm
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1.83
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Applications of Thulium-doped Yttrium Aluminium Garnet Crystal
- 2000 m laser
- Medical laser
- Laser radar
- Atmospheric detection
- Military technology
- Photoelectric countermeasures
- Remote sensing