Laser cooling via stimulated photon emissions

Patent metadata

Field	Value
Publication number	US-9788406-B2
Application number	US-201414546537-A
Country	US
Kind code	B2
Filing date	Nov 18, 2014
Priority date	Nov 18, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

An example laser cooling system may include a first laser to induce a transition of a plurality of electrons in a medium to an excited energy state via absorption of photons. The laser cooling system may also include a second laser to stimulate emission from the medium of emitted photons having a higher energy than an energy of the absorbed photons.

First claim

What is claimed is:

1. A laser cooling system comprising:
a first laser;
a second laser; and
a controller configured to:
cause the first laser to apply first light pulses to a medium to induce a transition of a plurality of electrons in the medium to an excited energy state via absorption of photons of the first light pulses, wherein the first light pulses have a first pulse width; and
cause the second laser to apply second light pulses to the medium to stimulate emission of photons from the medium, the emitted photons having a higher energy than an energy of the absorbed photons, wherein the second light pulses have a second pulse width, wherein the second pulse width is different from the first pulse width, and wherein the combined application of the first light pulses and the second light pulses produces a net cooling effect on the medium.

2. The laser cooling system of claim 1 , wherein the first laser is configured to generate the first light pulses at a first pulse rate, wherein the second laser is configured to generate the second light pulses at a second pulse rate, and wherein the first laser and the second laser comprise pulsed lasers.

3. The laser cooling system of claim 1 , wherein the first laser is configured to generate a particular light pulse of the first light pulses during a first time period corresponding to the first pulse width, wherein the second laser is configured to generate a particular light pulse of the second light pulses during a second time period corresponding to the second pulse width, and wherein the second time period is after the first time period.

4. The laser cooling system of claim 3 , wherein a third time period separates the first time period and the second time period, and wherein the third time period is less than a radiative lifetime associated with spontaneous emission of photons from the medium after the absorption of the absorbed photons.

5. The laser cooling system of claim 1 , wherein the first light pulses have a first wavelength, wherein the first wavelength is determined based on a photon absorption profile associated with the medium, and wherein the second light pulses have a second wavelength that is less than the first wavelength.

6. A method of laser cooling, the method comprising:
initiating a first laser to provide a first laser light pulse having a first wavelength toward a medium during a first time period to induce a transition of a plurality of electrons in the medium to an excited energy state via absorption of photons of the first laser light pulse, wherein the first laser light pulse has a first pulse width; and
initiating a second laser to provide a second laser light pulse having a second wavelength toward the medium during a second time period to stimulate emission of photons from the medium, the emitted photons having a higher energy than an energy of the absorbed photons, wherein the second laser light pulse has a second pulse width, wherein the second pulse width is different from the first pulse width, and wherein providing the first laser light pulse and the second laser light pulse toward the medium produces a net cooling effect on the medium.

7. The method of claim 6 , wherein a third time period occurs between the first time period and the second time period, and wherein the third time period is shorter than a radiative lifetime associated with spontaneous emission of photons from the medium after the absorption of the absorbed photons.

8. The method of claim 6 , wherein the first wavelength is determined based on a photon absorption profile associated with the medium, and wherein the second wavelength is less than the first wavelength, and wherein the first laser and the second laser are the same laser.

9. The method of claim 6 , wherein the first laser and the second laser comprise a single pulsed laser that provides the first laser light pulse at the first wavelength to the medium during the first time period and provides the second laser light pulse at the second wavelength to the medium during the second time period.

10. A laser cooling system comprising:
a first pulsed laser system;
a second pulsed laser system; and
a controller configured to:
cause the first pulsed laser system to direct first pulses of light having a first wavelength toward a medium to induce a transition of a plurality of electrons in the medium to an excited energy state via absorption of photons of the first pulses of light, wherein the first pulses of light have a first pulse width; and
cause the second pulsed laser system to direct second pulses of light having a second wavelength toward the medium to stimulate emission of photons from the medium, the emitted photons having a higher energy than an energy of the absorbed photons, wherein the second pulses of light have a second pulse width, wherein the second pulse width is different from the first pulse width, and wherein the combined application of the first pulses of light and the second pulses of light produces a net cooling effect on the medium.

11. The laser cooling system of claim 10 , further comprising the medium, wherein the first wavelength is determined based on a photon absorption profile associated with the medium, and wherein the second wavelength is less than the first wavelength.

12. The laser cooling system of claim 10 , wherein the second pulsed laser system is configured to direct a pulse of light having the second wavelength toward the medium after the first pulsed laser system has completed directing a pulse of light having the first wavelength toward the medium.

13. The laser cooling system of claim 10 , wherein the first pulsed laser system is configured to generate a particular pulse of the first pulses of light during a first time period corresponding to the first pulse width, wherein the second pulsed laser system is configured to generate a particular pulse of the second pulses of light during a second time period corresponding to the second pulse width, and wherein the second time period is after the first time period.

14. The laser cooling system of claim 13 , wherein a third time period occurs between the first time period and the second time period, and wherein the third time period is shorter than a radiative lifetime associated with spontaneous emission of photons from the medium after the absorption of the absorbed photons.

15. The laser cooling system of claim 1 , wherein the first laser is configured to generate the first light pulses on a red end of a photon absorption profile associated with the medium, and wherein the second laser is configured to generate the second light pulses on a blue end of the photon absorption profile associated with the medium.

16. The laser cooling system of claim 1 , wherein the first light pulses have a square wave profile, a sine wave profile, a sawtooth profile, or a trapezoidal profile, and wherein the first laser and the second laser have the same laser beam source.

17. The laser cooling system of claim 2 , wherein the first pulse rate is the same as the second pulse rate, and wherein the first light pulses and the second light pulses have a square wave profile.

18. The laser cooling system of claim 10 , wherein the first pulsed laser system comprises a plurality of lasers.

19. The laser cooling system of claim 1 , wherein the medium has a first temperature prior to application of the first light pulses, wherein the medium has a second temperature after application of the second light pulses, and wherein the second temperature is less than the first temperature.

Assignees

• Boeing Co

Inventors

• Klennert Wade L

Classifications

• H01S3/1618

  ytterbium · CPC title

• F25B23/00

  Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect · CPC title

• H01S3/0408

  Radiative cooling, e.g. by anti-Stokes scattering in the active medium · CPC title

• H01S3/17

  amorphous, e.g. glass · CPC title

• H01S3/042 Primary

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