Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorHamid Hemmati
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Abstract
A Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 .mu.m radiation with a pump power to output power of efficiency as high as 68%. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN.sub.2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77.degree. K. with an efficiency as high as 68% up to ambient room temperature with an efficiency at that temperature as high as 9%.
Claims12
A crystal laser optically pumped with low-level pump power for operation with very high optical-to-optical conversion efficiency of pump power to laser output power consisting essentially of
- a yttrium lithium fluoride host crystal rod having
- a length not greater than about 4 mm,
- a holmium activator, and
- a sensitizer consisting of only thulium,
- wherein holmium and thulium are provided in said crystal in concentrations of 0.4 % and 6% by weight, and including
- means for low-level power pumping of said crystal,
- a resonant cavity, and
- optical energy extracting means.
A crystal laser optically pumped with low-level pump power for operation with very high optical-to-optical conversion efficiency of pump power to laser output power over a range of about 77.degree. K. to about 300.degree. K. consisting essentially of
- a yttrium lithium fluoride host crystal rod having
- a length not greater than about 4 mm,
- a holmium activator, and
- a sensitizer consisting of only thulium,
- wherein holmium and thulium are provided in said crystal in concentrations of 0.4% and 6% by weight, and including
- means for low-level pumping of said crystal,
- a resonant cavity,
- means for cooling said crystal for operation at a temperature between about 77.degree. K. and about 300.degree. K. and
- optical energy extraction means.
Dependencies are inferred from the claim text.