Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

• US 7,537,395 B2
• Filed: 03/05/2007
• Issued: 05/26/2009
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Lockheed Martin Aculight Corp. (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Savage-Leuchs, Matthias P.
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): Nguyen; Tuan N.
• Application Number:
  US11/682,234
• Publication Number:
  US 20080037604A1
• Time in Patent Office: 813 Days
• Field of Search: 372/6, 372/22, 372/43.01, 356/300, 385/89, 385/92, 385/135
• US Class Current: 385/92
• CPC Class Codes: G02B 6/4249 comprising arrays of active devices and fibres
• CPC Class Codes: G02B 6/4296 coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources
• CPC Class Codes: H01S 3/0407 Liquid cooling, e.g. by water
• CPC Class Codes: H01S 3/042 for solid state lasers H01S3/0401 takes precedence
• CPC Class Codes: H01S 3/06704 Housings; Packages
• CPC Class Codes: H01S 3/094003 the pumped medium being a fibre
• CPC Class Codes: H01S 3/09408 Pump redundancy
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/02423 Liquid cooling, e.g. a liquid cools a mount of the laser

Abstract

Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

Claims

1. An optical coupling method for modular apparatus, the method comprising:

providing an enclosure, wherein the enclosure has a first external port and a second external port;

providing a first delivery fiber connected to the first port;

providing a first gain fiber, wherein a first end of the first gain fiber is connected to the delivery fiber, wherein the first gain fiber is outside the enclosure; and

within the enclosure;

generating laser light from a plurality of laser diodes that are within the enclosure;

collimating light from the plurality of laser diodes into a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

directing pump light inside the enclosure from the collimated pump-light beam to exit the enclosure via the first external port such that the pump light propagates through the delivery fiber to the first gain fiber, and wherein the directing of pump light inside the enclosure includes wavelength-selective transmitting the collimated pump-light beam towards the first port;

receiving signal light coming from the first gain fiber outside the enclosure through the delivery fiber and through the first external port, wherein the signal light has a characteristic second wavelength different than the first wavelength; and

directing signal light inside the enclosure between the first external port and the second external port such that light derived from the signal light exits the enclosure via the second external port, wherein the directing of signal light inside the enclosure includes wavelength-selective reflecting of signal light from the first port towards the second port.

2. The method of claim 1, further comprising:

non-linear wavelength converting, inside the enclosure, at least a portion of the signal light having the characteristic second wavelength to a characteristic third wavelength.

3. The method of claim 1, further comprising:

providing feedback inside the enclosure in order to lase the signal light.

4. An optical coupling method for modular apparatus, the method comprising:

providing an enclosure, wherein the enclosure has a first external port and a second external port;

providing a first delivery fiber connected to the first port;

providing a first gain fiber, wherein a first end of the first gain fiber is connected to the delivery fiber, wherein the first gain fiber is outside the enclosure; and

within the enclosure;

generating laser pump light from a plurality of laser diodes that are within the enclosure;

stabilizing the pump light using at least one grating;

collimating the pump light from the plurality of laser diodes into a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

directing the pump light inside the enclosure from the collimated pump-light beam to exit the enclosure into the delivery fiber via the first external port;

receiving signal light coming from the delivery fiber outside the enclosure through the first external port, wherein the signal light has a characteristic second wavelength different than the first wavelength; and

directing the signal light inside the enclosure between the first external port and the second external port such that light derived from the signal light exits the enclosure via the second external port; and

coupling a seed signal having the second wavelength to a second end of the first gain fiber such that the seed signal and the pump light counter-propagate in the first gain fiber; and

amplifying the seed signal in the first gain fiber using power from the pump light.

5. The method of claim 4, wherein the directing of signal light inside the enclosure includes wavelength-selective reflecting of signal light from the first port towards the second port and the directing of pump light inside the enclosure includes wavelength-selective transmitting the collimated pump-light beam towards the first port.

6. The method of claim 4, further comprising:

disconnecting the first end of the first delivery fiber from the first port;

directly connecting a first end of a second delivery fiber outside the enclosure to the first port, wherein the second delivery fiber is connected to a second gain fiber, and wherein one or more characteristics of the second gain fiber are different than corresponding characteristics of the first gain fiber;

coupling a seed signal to a second end of the second gain fiber such that the seed signal and the pump light counter-propagate in the second gain fiber; and

amplifying the seed signal in the second gain fiber using power from the pump light.

7. The method of claim 4, wherein the providing of the delivery fiber includes providing a photonic-crystal delivery fiber, and connecting the photonic-crystal delivery fiber to the enclosure using solder.

8. The method of claim 4, wherein the directing of signal light inside the enclosure includes wavelength-selective transmitting of a signal light from the first port towards the second port and the directing of pump light inside the enclosure includes wavelength-selective reflecting the collimated pump-light beam towards the first port.

9. An optical coupling method for modular apparatus, the method comprising:

providing an enclosure, wherein the enclosure has a first external port and a second external port;

connecting a first delivery fiber to the first port;

connecting a first end of a first gain fiber to the delivery fiber, wherein the first gain fiber is outside the enclosure; and

within the enclosure;

generating laser pump light from one or more laser diodes that are within the enclosure;

collimating the pump light from the one or more laser diodes into a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

directing the pump light inside the enclosure from the collimated pump-light beam to exit the enclosure via the first external port such that the pump light propagates through the delivery fiber to the gain fiber, and signal light from the gain fiber propagates through the delivery fiber to the first external port;

receiving the signal light coming from outside the enclosure through the first external port, wherein the signal light has a characteristic second wavelength different than the first wavelength;

directing the signal light inside the enclosure between the first external port and the second external port such that light derived from the signal light exits the enclosure via the second external port; and

coupling signal feedback having the second wavelength to the first gain fiber such that lasing occurs in-the first gain fiber using power from the pump light.

10. The method of claim 9, wherein the first gain fiber is a polarization-maintaining fiber, the method further comprising:

maintaining a polarization of the signal light within the enclosure.

11. A modular optical coupling apparatus comprising:

an enclosure, wherein the enclosure has a first external port and a second external port;

a plurality of laser diodes held within the enclosure, and configured to output pump light;

a beam shaper held within the enclosure and optically coupled to receive pump light from the plurality of laser diodes and to provide a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

at least one stabilization grating located in an optical path between the plurality of laser diodes and the beam shaper and configured to stabilize the pump light;

a first wavelength-selective optical element configured to direct pump light inside the enclosure from the collimated pump-light beam to the first external port and to direct signal light inside the enclosure between the first external port and the second external port, wherein the signal light has a characteristic second wavelength different than the first wavelength;

a delivery fiber outside the enclosure, wherein a first end of the delivery fiber is connected to the first port; and

a first gain fiber outside the enclosure, wherein a first end of the first gain fiber is connected to a second end of the delivery fiber.

12. The apparatus of claim 11, further comprising:

a second wavelength-selective optical element located between the first wavelength-selective optical element and the plurality of laser diodes and configured to substantially block, inside the enclosure, signal light from reaching the one or more laser diodes, wherein at least the first wavelength-selective element includes a dichroic mirror.

13. The apparatus of claim 11, further comprising:

a non-linear wavelength converter held inside the enclosure and operable to receive the signal light from the first port having the characteristic second wavelength and to convert at least a portion of the signal light having the characteristic second wavelength to a characteristic third wavelength.

14. A modular optical-coupling apparatus comprising:

an enclosure, wherein the enclosure has a first external port and a second external port;

one or more laser diodes held within the enclosure;

a beam shaper held within the enclosure and optically coupled to receive pump light from one or more laser diodes and to provide a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

a first wavelength-selective optical element configured to direct pump light inside the enclosure from the collimated pump-light beam to exit the enclosure through the first external port and to direct signal light inside the enclosure between the first external port and the second external port, wherein the signal light has a characteristic second wavelength different than the first wavelength;

a delivery fiber outside the enclosure, wherein a first end of the delivery fiber is directly connected to the first port;

a first gain fiber outside the enclosure, wherein a first end of the first gain fiber is connected to a second end of the delivery fiber; and

a seed-signal source that supplies a seed signal having the second wavelength to a second end of the first gain fiber such that the seed signal and the pump light counter-propagate in the first gain fiber, and wherein the apparatus is configured to amplify the seed signal in the first gain fiber using power from the pump light.

15. The apparatus of claim 14, further comprising:

a gain medium coupled to the first port; and

one or more feedback elements configured to form a laser using the gain medium.

16. The apparatus of claim 14, wherein the first wavelength-selective optical element includes a dichroic beam-splitter mirror configured to reflect the signal light from the first port towards the second port and to transmit the collimated pump-light beam towards the first port.

17. The apparatus of claim 14, further comprising:

a second gain fiber, wherein a first end of the second gain fiber is configured to be directly connected to the delivery fiber, and the apparatus is configured to enable the first gain fiber to be disconnected from the delivery fiber and exchanged by having the second gain fiber connected to the first port.

18. The apparatus of claim 14, wherein the first gain fiber is a polarization-maintaining fiber, and wherein the apparatus is configured to maintain a polarization of the signal light within the enclosure.

19. The apparatus of claim 14,

wherein the delivery fiber is a hollow-core photonic-bandgap fiber having a hollow-endcap termination at a first end.

20. The apparatus of claim 14, wherein the first wavelength-selective optical element includes a dichroic beam-splitter mirror configured to signal light from the first port towards the second port and to transmit the collimated pump-light beam towards the first port.

21. A modular optical coupling apparatus comprising:

an enclosure, wherein the enclosure has a first external port and a second external port;

a plurality of laser diodes held within the enclosure;

means for combining laser light from the plurality of laser diodes into a collimated pump-light beam;

means for directing pump light inside the enclosure from the collimated pump-light beam to exit the enclosure through the first external port, and wherein the means for directing of pump light inside the enclosure includes means for wavelength-selective transmitting the collimated pump-light beam towards the first port;

a delivery fiber located external to the enclosure and configured to couple the pump light from the first external port to a gain fiber and to couple signal light from the gain fiber to the first eternal port, wherein the delivery fiber is connected to the first external port; and

means for directing signal light inside the enclosure between the first external port and the second external port, wherein the signal light has a characteristic second wavelength different than the first wavelength, wherein the means for directing of signal light inside the enclosure includes means for wavelength-selective reflecting of signal light from the first port towards the second port.

22. The apparatus of claim 21, further comprising:

means for non-linear wavelength converting, inside the enclosure, at least a portion of the signal light having the characteristic second wavelength to a characteristic third wavelength.

23. The apparatus of claim 21, further comprising:

means for providing feedback inside the enclosure in order to lase the signal light.

24. A modular optical coupling apparatus comprising:

an enclosure, wherein the enclosure has a first external port and a second external port;

a plurality of laser diodes that are held within the enclosure and that generate pump light;

means for stabilizing the pump light using at least one grating;

means for collimating the pump light from the the plurality of laser diodes into a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

means for directing pump light inside the enclosure from the collimated pump-light beam to exit the enclosure through the first external port, wherein the means for directing pump light inside the enclosure is transmissive to pump light;

means for directing signal light inside the enclosure between the first external port and the second external port, wherein the signal light has a characteristic second wavelength different than the first wavelength, wherein the means for directing signal light inside the enclosure is reflective to signal light;

delivery-fiber means for coupling light between a first end of a first gain fiber outside the enclosure and the first port;

means for coupling a seed signal having the second wavelength to a second end of the first gain fiber such that the seed signal and the pump light counter-propagate in the first gain fiber; and

means for amplifying the seed signal in the first gain fiber using power from the pump light.

25. The apparatus of claim 24, wherein the means for directing of signal light inside the enclosure includes means for wavelength-selective reflecting of signal light from the first port towards the second port and the means for directing of pump light inside the enclosure includes means for wavelength-selective transmitting the collimated pump-light beam towards the first port.

26. The apparatus of claim 24, wherein the first gain fiber is a polarization-maintaining fiber, the apparatus farther comprising:

means for maintaining a polarization of the signal light within the enclosure.

27. The apparatus of claim 24, wherein the delivery-fiber means further includes

a delivery fiber located outside the enclosure and having a first end permanently affixed to the first port

and a second end connected to the first end of the gain fiber outside the enclosure.

28. The apparatus of claim 24, wherein the means for directing of signal light inside the enclosure includes means for wavelength-selective transmitting of a signal light from the first port towards the second port and the means for directing of pump light inside the enclosure includes means for wavelength-selective reflecting the collimated pump-light beam towards the first port.

29. A modular optical coupling apparatus comprising:

an enclosure, wherein the enclosure has a first external port and a second external port;

one or more laser diodes held within the enclosure;

means for collimating the pump light from the one or more laser diodes into a collimated pump-light beam, wherein the pump light in the collimated pump-light beam has a characteristic first wavelength;

means for directing pump light inside the enclosure from the collimated pump-light beam to the first external port;

delivery-fiber means for coupling the pump light from the first external port to a gain fiber and for coupling signal light from the gain fiber to the first eternal port, wherein the delivery-fiber means is external to the enclosure and is connected to the first external port;

means for directing signal light inside the enclosure between the first external port and the second external port, wherein the signal light has a characteristic second wavelength different than the first wavelength;

means for coupling signal feedback having the second wavelength to the first gain fiber; and

means for lasing in the first gain fiber using power from the pump light.

30. The apparatus of claim 29, further comprising:

means for disconnecting the first gain fiber;

means for connecting a second gain fiber outside the enclosure to the delivery-fiber means, wherein one or more characteristics of the second gain fiber are different than corresponding characteristics of the first gain fiber;

means for coupling a seed signal having the second wavelength to a second end of the second gain fiber such that the seed signal and the pump light counter-propagate in the second gain fiber; and

means for amplifying the seed signal in the second gain fiber using power from the pump light.