Apparatus and method for suppressing parasitic lasing and applications thereof

Patent metadata

Field	Value
Publication number	US-9899798-B2
Application number	US-201514816166-A
Country	US
Kind code	B2
Filing date	Aug 3, 2015
Priority date	Aug 3, 2015
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

Apparatus and methods that enable the suppression of amplified spontaneous emission (ASE) and prevention against parasitic lasing in cryogenically-cooled laser amplifier systems, thus allowing sustainable extraction efficiency when increasing the pump power and suitable for large-scale, high average-power laser systems employing large-aperture gain media. A gain medium having a known index of refraction for operation in an evacuated, cryogenic environment includes an ASE-absorbing epoxy composition on the perimetrical edge of the gain medium, wherein the epoxy composition has an index of refraction that substantially matches the index of refraction of the gain medium.

First claim

We claim:

1. A method to reduce and/or eliminate gain clamping in a solid state laser/amplifier apparatus, comprising:
providing a solid state laser/amplifier apparatus designed for operation in an evacuated, cryogenic environment, comprising:
a gain medium having a known index of refraction,
having a perimetrical edge; and
an amplified spontaneous emission (ASE)-absorbing epoxy composition disposed on at least a portion of the perimetrical edge of the gain medium, wherein the epoxy composition has an index of refraction that substantially matches the index of refraction of the gain medium, wherein the ASE-absorbing epoxy composition is a mixture of Stycast 1266 and Stycast 2850 epoxy resins,

further wherein the gain medium is characterized by a gain clamping parameter that is greater than a gain clamping parameter of a similar gain medium of a laser/amplifier apparatus designed for operation in an evacuated, cryogenic environment that does not include an ASE-absorbing epoxy composition disposed on at least a portion of the perimetrical edge of the similar gain medium, wherein the epoxy composition has an index of refraction that substantially matches the index of refraction of the similar gain medium; and
coupling out from the gain medium at least a portion of transversely propagating ASE so as to prevent a build-up of parasitic oscillations in the gain medium.

2. The method of claim 1 , wherein the perimetrical edge of the gain medium is a diffuse surface.

3. The method of claim 1 , wherein the ASE-absorbing epoxy composition has a thickness equal to or greater than 10 microns (μm) and equal to or less than 1 centimeter (cm).

4. The method of claim 1 , further comprising disposing the gain medium including the ASE-absorbing epoxy composition disposed on at least a portion of the perimetrical edge of the gain medium in a cryorefrigerator.

5. The method of claim 1 , comprising providing a Ti:Sapphire gain medium.

6. The method of claim 1 , wherein the ASE-absorbing epoxy composition comprises at least two epoxy components each having a different index of refraction and combining the at least two epoxy components in a predetermined proportion to achieve the epoxy composition index of refraction that substantially matches the index of refraction of the gain medium.

7. The method of claim 6 , wherein the epoxy composition index of refraction matches the index of refraction of the gain medium to within five percent.

8. The method of claim 6 , wherein the at least two epoxy components are low temperature-compatible epoxy components.

9. The method of claim 8 , wherein the low temperature is equal to or less than zero degrees centigrade.

10. The method of claim 8 , wherein the low temperature is equal to or less than 200 Kelvin.

11. The method of claim 6 , wherein the ASE-absorbing epoxy composition includes an ASE-absorbing optical dopant.

12. The method of claim 11 , wherein the ASE-absorbing optical dopant consists of metal particles.

13. The method of claim 12 , wherein the metal particles have sizes that are equal to or less than 10 μm.

14. The method of claim 11 , wherein the ASE-absorbing optical dopant is selected from a group consisting of graphite, graphene, iron and powders absorbing near a gain crystal's ASE wavelength.

15. The method of claim 1 , further comprising providing a bonding base intermediate the perimetrical edge of the gain medium and the ASE-absorbing epoxy composition, wherein the bonding base comprises a low-temperature epoxy.

16. The method of claim 15 , wherein the bonding base further includes an optical dopant that enables at least one of refractive index tuning and ASE absorption.

17. The method of claim 16 , comprising adjusting the index-tuning optical dopant level in the bonding base to tune the refractive index and adjusting the ASE-absorbing optical dopant level to control a thermal profile and ASE absorption profile of the solid state laser/amplifier apparatus.

18. The method of claim 16 , wherein the optical dopant is a powdered optical material.

19. The method of claim 16 , wherein the optical dopant has a refractive index that is greater than a refractive index of the transparent, low-temperature epoxy of the bonding base.

20. The method of claim 15 , wherein the bonding base is Stycast 1266 and the optical dopant is SrTiO 3 .

21. A solid state laser/amplifier apparatus designed for operation in an evacuated, cryogenic environment, comprising:
a gain medium having a known index of refraction, wherein the gain medium has a perimetrical edge; and
an amplified spontaneous emission (ASE)-absorbing epoxy composition disposed on at least a portion of the perimetrical edge of the gain medium, wherein the epoxy composition has an index of refraction that substantially matches the index of refraction of the gain medium, wherein the ASE-absorbing epoxy composition is a mixture of Stycast 1266 and Stycast 2850 epoxy resins,

further wherein the gain medium is characterized by a gain clamping parameter that is greater than a gain clamping parameter of a similar gain medium of a laser/amplifier apparatus designed for operation in an evacuated, cryogenic environment that does not include an ASE-absorbing epoxy composition disposed on at least a portion of the perimetrical edge of the similar gain medium, wherein the epoxy composition has an index of refraction that substantially matches the index of refraction of the similar gain medium.

22. The solid state laser/amplifier apparatus of claim 21 , wherein the perimetrical edge of the gain medium is a diffuse surface.

23. The solid state laser/amplifier apparatus of claim 21 , wherein the ASE-absorbing epoxy composition has a thickness equal to or greater than 10 microns (μm) and equal to or less than 1 centimeter (cm).

24. The solid state laser/amplifier apparatus of claim 21 , wherein the gain medium including the ASE-absorbing epoxy composition is disposed on a cold finger of a cryorefrigerator.

25. The solid state laser/amplifier apparatus of claim 21 , wherein the gain medium is a Ti:Sapphire crystal.

26. The solid state laser/amplifier apparatus of claim 21 , wherein the ASE-absorbing epoxy composition comprises at least two epoxy components each having a different index of refraction, in a predetermined proportion to achieve the epoxy composition index of refraction that substantially matches the index of refraction of the gain medium.

27. The solid state laser/amplifier apparatus of claim 26 , wherein the at least two epoxy components are low temperature-compatible epoxy components.

28. The solid state laser/amplifier apparatus of claim 26 , wherein the ASE-absorbing epoxy composition includes an ASE-absorbing optical dopant.

29. The solid state laser/amplifier apparatus of claim 28 , wherein the ASE-absorbing optical dopant consists of metal particles.

30. The solid state laser/amplifier apparatus of claim 29 , wherein the metal particles have sizes that are equal to or less than 10 μm.

31. The solid state laser/amplifier apparatus of claim 29 , wherein the ASE-absorbing optical dopant is selected from a group consisting of graphite, graphene, iron and powders absorbing near a gain crystal's ASE wavelength.

32. The solid state laser/amplifier apparatus of claim 21 , further comprising a bondin

Assignees

• Univ Central Florida Res Found Inc

Inventors

• Chang Zenghu
• Wu Yi
• Cunningham Eric

Classifications

• H01S3/1625

  titanium · CPC title

• H01S3/1636

  Al2O3 (Sapphire) · CPC title

• H01S5/0226

  Electricity · mapped topic

• H01S2301/02

  ASE (amplified spontaneous emission), noise; Reduction thereof · CPC title

• H01S3/042

  for solid state lasers {(H01S3/0401 takes precedence)} · CPC title