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US-20260128562-A1 - EXTREME-COLD HIGH-POWER LASER SYSTEM

US20260128562A1US 20260128562 A1US20260128562 A1US 20260128562A1US-20260128562-A1

Abstract

A laser system may include one or more pump lasers configured to provide pump light. The laser system may include an amplifier having one or more gain media cooled below 20° C. using a liquid coolant and configured to amplify seed light having a wavelength at or greater than 2 micrometers. The laser system may include an enclosure with an atmospheric regulator to enclose at least an optical path of at least the gain media and maintain an atmosphere of dry gas.

Inventors

  • Chase Evan Geiger
  • Zenghu Chang
  • Yi Wu

Assignees

  • UNIVERSITY OF CENTRAL FLORIDA RESEARCH FOUNDATION, INC.
  • UNIVERSITY OF OTTAWA

Dates

Publication Date
20260507
Application Date
20251106

Claims (20)

  1. 1 . A laser system comprising: one or more pump lasers configured to provide pump light; an amplifier including one or more gain media configured to amplify seed light, wherein the one or more gain media have at least one of a quasi-three-level energy system or a quasi-four-level energy system; a cooling system configured to cool the one or more gain media to a temperature at or below −20° C. using a liquid coolant; and an enclosure with an atmospheric regulator to enclose at least the one or more gain media and maintain an atmosphere of dry gas.
  2. 2 . The laser system of claim 1 , wherein the liquid coolant comprises ethanol.
  3. 3 . The laser system of claim 1 , wherein the one or more gain media comprise a rare-earth dopant.
  4. 4 . The laser system of claim 1 , wherein the one or more gain media comprise holmium-doped yttrium lithium fluoride (Ho:YLF).
  5. 5 . The laser system of claim 1 , wherein the seed light has a wavelength at or above 2 micrometers.
  6. 6 . The laser system of claim 1 , wherein the one or more gain media are cooled to a temperature between −20° C. and −70° C.
  7. 7 . The laser system of claim 1 , further comprising thermal insulation positioned between the one or more gain media and a support structure to insulate the one or more gain media.
  8. 8 . The laser system of claim 1 , wherein the atmospheric regulator maintains the atmosphere at less than 0.1 percent humidity.
  9. 9 . The laser system of claim 8 , wherein the dry gas comprises dry air supplied by a dehumidification system.
  10. 10 . The laser system of claim 1 , wherein the enclosure further encloses the pump light for pumping the one or more gain media.
  11. 11 . A chirped-pulse amplifier comprising: a stretcher configured to receive pulsed seed light and generate chirped seed light; one or more gain media configured to amplify the chirped seed light, wherein the one or more gain media have at least one of a quasi-three-level energy system or a quasi-four-level energy system; a cooling system configured to cool the one or more gain media to a temperature below −20° C. using a liquid coolant; a compressor configured to compress amplified chirped seed light to generate output light; and thermal insulation positioned between the one or more gain media and surrounding support structures.
  12. 12 . The chirped-pulse amplifier of claim 11 , wherein the one or more gain media comprise a rare-earth dopant.
  13. 13 . The chirped-pulse amplifier of claim 11 , wherein the one or more gain media comprise holmium-doped yttrium lithium fluoride (Ho:YLF).
  14. 14 . The chirped-pulse amplifier of claim 11 , wherein the pulsed seed light has a wavelength at or above 2 micrometers.
  15. 15 . The chirped-pulse amplifier of claim 11 , wherein the one or more gain media are maintained at a between −20° C. and −70° C.
  16. 16 . The chirped-pulse amplifier of claim 15 , further comprising an enclosure with an atmospheric regulator configured to maintain an atmosphere of dry gas around the stretcher, gain media, and the compressor.
  17. 17 . The chirped-pulse amplifier of claim 16 , wherein the atmospheric regulator maintains the atmosphere at less than 0.1 percent humidity.
  18. 18 . The chirped-pulse amplifier of claim 17 , wherein the dry gas comprises dry air supplied by a dehumidification system.
  19. 19 . The chirped-pulse amplifier of claim 11 , wherein the stretcher and the compressor each comprise a chirped volume Bragg grating (CVBG).
  20. 20 . A method of operating a laser system comprising: providing pump light from one or more pump lasers; cooling one or more gain media to a temperature below −20° C. using a liquid coolant, wherein the one or more gain media have at least one of a quasi-three-level energy system or a quasi-four-level energy system; amplifying seed light using the one or more gain media; and maintaining an atmosphere of dry gas around at least an optical path of the seed light using an atmospheric regulator within an enclosure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 63/717,143, filed Nov. 6, 2024, which is incorporated herein by reference in the entirety. GOVERNMENT LICENSE RIGHTS The invention was made with Government support under grant number 2207674 awarded by the National Science Foundation (NSF) and grant number FA9550-20-1-0295 awarded by the U.S. Air Force Office of Scientific Research (AFOSR). The Government has certain rights to the invention. TECHNICAL FIELD The present disclosure relates to laser cooling systems, and more particularly to an extreme-cold high-power laser system using liquid coolant refrigeration to cool gain media below 0° C. for amplifying seed light having wavelengths around and/or greater than 2 micrometers. BACKGROUND High-power laser systems operating at wavelengths around and/or greater than 2 micrometers have found increasing applications in scientific research, industrial processing, and medical procedures. These systems typically employ rare-earth-doped gain media such as holmium-doped or thulium-doped crystals to achieve amplification at these short-wave infrared wavelengths. However, the performance of such laser systems is often limited by thermal effects that arise during high-power operation, including reduced gain efficiency, thermal lensing, and depolarization losses that can degrade beam quality and limit achievable output powers. Conventional cooling approaches for these laser systems include water cooling at room temperature or cryogenic cooling using liquid nitrogen at extremely low temperatures around −196° C. While cryogenic systems can provide enhanced performance through improved gain characteristics, they introduce substantial complexity, cost, and operational challenges including the need for vacuum chambers, specialized vacuum pumping systems, and handling of cryogenic fluids. Room temperature cooling systems, while simpler to implement, may not provide sufficient thermal management for high-power applications where enhanced gain performance is desired. There remains a need for cooling solutions that can provide improved performance over room temperature systems while avoiding the complexity and cost associated with cryogenic approaches. SUMMARY In some embodiments, a laser system is provided. The laser system may include one or more pump lasers configured to provide pump light. The laser system may include an amplifier including one or more gain media configured to amplify seed light. The one or more gain media may have at least one of a quasi-three-level energy system or a quasi-four-level energy system. The laser system may include a cooling system configured to cool the one or more gain media to a temperature at or below −20° C. using a liquid coolant. The laser system may include an enclosure with an atmospheric regulator to enclose at least the one or more gain media and maintain an atmosphere of dry gas. In some embodiments, the liquid coolant may include ethanol. In some embodiments, the one or more gain media may include a rare-earth dopant. In some embodiments, the one or more gain media may include holmium-doped yttrium lithium fluoride (Ho:YLF). In some embodiments, the seed light may have a wavelength at or above 2 micrometers. In some embodiments, the one or more gain media may be cooled to a temperature between −20° C. and −70° C. In some embodiments, the laser system may further include thermal insulation positioned between the one or more gain media and a support structure to insulate the one or more gain media. In some embodiments, the atmospheric regulator may maintain the atmosphere at less than 0.1 percent humidity. In some embodiments, the dry gas may include dry air supplied by a dehumidification system. In some embodiments, the enclosure may further enclose pump light for pumping the one or more gain media. In some embodiments, a chirped-pulse amplifier (CPA) is provided. The CPA may include a stretcher configured to receive pulsed seed light and generate chirped seed light. The CPA may include one or more gain media configured to amplify the chirped seed light. The one or more gain media may have at least one of a quasi-three-level energy system or a quasi-four-level energy system. The CPA may include a cooling system configured to cool the one or more gain media to a temperature below −20° C. using a liquid coolant. The CPA may include a compressor configured to compress amplified chirped seed light to generate output light. The CPA may include thermal insulation positioned between the one or more gain media and surrounding support structures. In some embodiments, the one or more gain media may include a rare-earth dopant. In some embodiments, the one or more gain media may include Ho:YLF. In some embodiments, the seed light may have a wavelength at or above 2 micrometers. In some embodiments, the Ho:YLF gain media may be maintained at a tempe