Chromium, Thulium, Holmium-Doped : Yttrium Aluminium Garnet Laser Crystals

CTH:YAGCTH:YAG -yttrium aluminium garnet laser crystals doped with chromium, thulium and holmium ions to provide lasing at 2.13 microns are finding more and more applications, especially in the medical industry. The inherent advantage of the crystal is that it employs YAG as the host. YAG's physical, thermal and optical properties are well known and understood by every laser designer.

Lasers operating at 2.13 microns couple well into water and body fluids, and can take advantage of using silica fibers for easy, accurate beam delivery. CTH:YAG can be readily Q-switched with either electro-optic material such as LiNbO3 or acousto-optics. Lasers using CTH:YAG are successfully used for medical procedures such as fragmentation of gallstones and for vascular welding.

Proprietary crystal preparation technology has been developed to overcome poor lasing efficiency, one of the major impediments to the use of laser materials in the 2 microns wavelength range. This technology allows production of CTH:YAG laser crystals with high optical quality, low scattering losses, and high efficiency. CTH:YAG laser crystals optimise the usefulness of the sensitiser ions for the holmium basing conditions at room temperature.

CTH:YAG laser crystals are offerred in sizes from 3 mm to 10 mm diameter, with lengths up to 150 mm long. Call upon our depth of experience in research, crystal growth and laser rod fabrication. Roditi will work with you to produce CTH:YAG laser crystals that meet the exact specifications for superior performance of your 2.13 microns laser system.


Designed for 2.13 µm output wavelength CTH:YAG is an excellent choice for Medical Laser Applications

Optical and Laser Properties

Laser Action 4 Level Laser Upper Laser Level 5I7
Emission Lifetime 7.8 msec Lower Level 5I8
Absorption Bands Flashlamp Pumped Refractive Index 1.8 at 632 nm
Output Wavelength 2.13 µm at 20°C flashlamp pump Chemical Formula Y3Al5O12:Cr,Tm,Ho
Emission Cross-Section Σ = 0.98 x 10-20 cm2  

CTH:YAG Laser Rod Standard Fabrication Specifications

Feature Standard Special Order
Crystal Orientation <111> within 5° Available
Diameter 3 mm to 10mm Available
Daimeter Tolerance +0.0 mm/- 0.05 mm Available
Length (plano/plano) 30 mm to 150 mm Available
Length Tolerance ± 0.75 mm ± 0.50 mm
Perpendiculairity of End Faces (plano/plano) 5 arc-minutes 2 arc-minutes
Parallelism of End Faces (plano/plano) 10 arc-seconds
Flatness 0.1 wave maximum 0.10 wave maximum
(plano/plano) over 90% of aperture over full aperture
Surface Finish at 5X 20-10 (scratch & dig) 10-5 (scratch & dig)
Barrel Finish 400 grit Polished approx. 80-50
End Face Bevel 0.075 mm to 0.12 mm at 45° angle
Chips No chips allowed on end face of rod; chip having maximum length of 0.3 mm permitted to lie in the area of bevel and barrel surfaces.
End Configurations plano/plano, plano/wedge, wedge/wedge or Brewster cut.  Plano ends can be finished flat, concave or convex
Coatings Standard coating is AR at 2.13 µm with R<0.25% each face. Other coatings available.