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US4974230A
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Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array
Assignee: National Aeronautics and Space Administration
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Filing: 1988-08-23
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Granted: 1990-11-27
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Expires: 2008-08-23
Abstract
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 μm 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 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° K. with an efficiency as high as 68% up to ambient room temperature with an efficiency at that temperature as high as 9%.
Inventors
- 👤 Hamid Hemmati
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:43
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/14; H01S3/16; H01S3/09; H01S3/091; H01S3/094; H01S3/0941; H01S3/09415; H01S3/09403; H01S3/1601; H01S3/1603; H01S3/161; H01S3/1616; H01S3/163; H01S3/1645; H01S3/1653
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
89 words
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.
Claim 2
Dependent Claim
89 words
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.
Claim 3
Dependent Claim
21 words
A crystal laser as defined in claim 1 including means for regulating the temperature of said crystal at about 300° K.
Claim 4
Dependent Claim
21 words
A crystal laser as defined in claim 1 including means for regulating the temperature of said crystal at about 77° K.
Claim 5
Dependent Claim
25 words
A crystal laser as defined in claim 1 wherein said means for low-level power pumping of said crystal is comprised of a semiconductor diode laser.
Claim 6
Dependent Claim
60 words
A crystal laser as defined in claim 1 wherein said means for low-level power pumping of said crystal is comprised of a plurality of semiconductor diode lasers and means for combining light from said plurality of semiconductor diode lasers with the same polarization to effectively combine the pump power supplied to said crystal from said plurality of semiconductor diode lasers.
Claim 7
Dependent Claim
25 words
A crystal laser as defined in claim 1 wherein holmium and thulium are provided in said crystal in concentrations of 0.4% and 6% by weight.
Claim 8
Dependent Claim
23 words
A crystal laser as defined in claim 6 including means for cooling said crystal for operation at a temperature below about 300° K.
Claim 9
Dependent Claim
21 words
A crystal laser as defined in claim 6 including means for regulating the temperature of said crystal at about 300° K.
Claim 10
Dependent Claim
21 words
A crystal laser as defined in claim 6 including means for regulating the temperature of said crystal at about 77° K.
Claim 11
Dependent Claim
22 words
A crystal laser as defined in claim 6 wherein said crystal rod is of a length not greater than about 2 mm.
Claim 12
Dependent Claim
22 words
A crystal rod as defined in claim 6 wherein said crystal rod is of a length not greater than about 2 mm.
Claim 13
Dependent Claim
116 words
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° K. to about 300° 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° K. and about 300° K. and optical energy extraction means.
Claim 14
Dependent Claim
116 words
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° K. to about 300° 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° K. and about 300° K. and optical energy extraction means.
References Cited (Backward Citations)
US4015217A
Cited
US4044315A
Cited
US3624549A
Cited
US3972007A
Cited
US3753145A
Cited
US3866142A
Cited
US3949319A
Cited
US3984524A
Cited
US4110702A
Cited
US4194170A
Cited
US4176326A
Cited
US4347485A
Cited
US4227159A
Cited
US4330763A
Cited
US4321559A
Cited
US4461006A
Cited
US4713820A
Cited
US4710940A
Cited
US4797893A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-11-26 | 1994-05-28 | 1994-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-26 | 1998-05-28 | 1998-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-26 | 2002-05-28 | 2002-11-27 | $7700.00 | Window Closed / Lapsed |