Spectral-beam combining for high-power fiber-ring-laser systems

• US 8,526,110 B1
• Filed: 02/17/2009
• Issued: 09/03/2013
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Honea, Eric C., Loftus, Thomas H., Lemaire, Charles A.
• Primary Examiner(s): CHERRY, EUNCHA P
• Application Number:
  US12/291,031
• Time in Patent Office: 1,659 Days
• Field of Search: 359/556, 359/327, 359/341.3, 359/341.4, 359/349, 359/554, 359/555
• US Class Current: 359/556
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: H01S 3/06712 Polarising fibre; Polariser
• CPC Class Codes: H01S 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap
• CPC Class Codes: H01S 3/06791 Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/0812 using a diffraction grating
• CPC Class Codes: H01S 3/117 using intracavity acousto-optic devices
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2391 emitting at different wavelengths

Abstract

A ring-laser system that includes a plurality of ring-laser gain elements and a spectral-beam-combining output stage configured to combine a plurality of beams coming from the gain elements into an output beam and that includes chromatic-dispersion compensation. In some embodiments, the output stage includes a plurality of highly reflective dielectric-coated focussing elements. In some embodiments, the output stage includes a plurality of high-efficiency dielectric-coated grating elements. In some embodiments, the output stage includes a mostly reflective but partially transmissive output mirror and a highly reflective beam-reversing mirror configured to reflect a majority of a backward-traveling signal beam such that it becomes forward traveling. In some embodiments, each gain element further includes a photonic-crystal-rod power amplifier. Some embodiments have an amplitude modulator configured to pulse the plurality of beams, and a timing controller configured to synchronize the pulses of the plurality of beams. Some embodiments further include a non-linear wavelength-conversion device.

Claims

1. An apparatus comprising:

a ring-laser system that includes a plurality of ring-laser gain elements and a spectral-beam-combining output stage configured to combine a plurality of beams coming from the gain elements into an output beam and that includes chromatic-dispersion compensation.

2. The apparatus of claim 1, wherein the output stage includes a plurality of highly reflective dielectric-coated focussing elements.

3. The apparatus of claim 1, wherein the output stage includes a plurality of high-efficiency dielectric-coated grating elements.

4. The apparatus of claim 1, wherein the output stage includes a mostly reflective but partially transmissive output mirror and a highly reflective beam-reversing mirror configured to reflect a majority of a backward-traveling signal beam such that it becomes forward traveling.

5. The apparatus of claim 1, at least one of the gain elements further comprising a photonic-crystal-rod power amplifier.

6. The apparatus of claim 1, further comprising:

an amplitude modulator configured to pulse the plurality of beams, and

a timing controller configured to synchronize the pulses of the plurality of beams.

7. The apparatus of claim 6, further comprising a non-linear wavelength-conversion device.

8. The apparatus of claim 1, wherein the gain elements obtain feedback signal from a spectrally separated portion of the output beam.

9. The apparatus of claim 1, wherein the output stage includes a segmented grating configured to combine intermediate output beams of the gain elements, wherein the intermediate output beams are arranged in a two-dimensional array.

10. The apparatus of claim 1, wherein each one of the gain elements further includes a bend-compensating index gradient.

11. A method comprising:

chromatic-dispersion compensating each of a plurality of laser beams coming from a plurality of gain elements;

spectral-beam combining the plurality of chromatic-dispersion compensated beams into a combined intermediate output beam;

outputting a majority of the combined intermediate output beam as an output beam;

separating a remaining portion of the combined intermediate output beam into different wavelengths; and

using the different wavelengths as feedback in a ring configuration to the plurality of gain elements.

12. The method of claim 11, further comprising reflecting the plurality of laser beams using a plurality of highly reflective dielectric-coated focussing elements.

13. The method of claim 11, further comprising diffracting the plurality of laser beams using a plurality of high-efficiency dielectric-coated grating elements.

14. The method of claim 11, further comprising reflecting the majority of the combined intermediate output beam from a mostly reflective but partially transmissive output mirror, and reflecting a majority of a backward-traveling signal beam such that it becomes forward traveling.

15. The method of claim 11, further comprising using a photonic-crystal-rod power amplifier in at least one of the gain elements.

16. The method of claim 11, further comprising:

amplitude modulating the plurality of beams to pulse them, and

synchronizing the pulses of the plurality of beams.

17. The method of claim 16, further comprising non-linear wavelength-converting the output beam to a wavelength other than that of the output beam.

18. The method of claim 11, further comprising segmenting intermediate output beams of the gain elements in a two-dimensional array of laser beams of a plurality of different wavelengths.

19. The method of claim 11, further comprising providing a bend-compensating index gradient in each one of the plurality of gain elements.

20. An apparatus comprising:

means for chromatic-dispersion compensating each of a plurality of laser beams coming from a plurality of gain elements;

means for spectral-beam combining the plurality of chromatic-dispersion compensated beams into a combined intermediate output beam;

means for outputting a majority of the combined intermediate output beam as an output beam;

means for separating a remaining portion of the combined intermediate output beam into different wavelengths; and

means for using the different wavelengths as feedback in a ring configuration to the plurality of gain elements.