Temperature control of a fiber laser system

• US 8,971,359 B2
• Filed: 04/12/2012
• Issued: 03/03/2015
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Creeden, Daniel J., Marcinuk, Adam J., Willis, Chris L.
• Primary Examiner(s): Rodriguez, Armando
• Application Number:
  US13/809,467
• Publication Number:
  US 20130136146A1
• Time in Patent Office: 1,055 Days
• Field of Search: 372/6, 372/34, 372/36, 372/50.11, 372/102, 385/134
• US Class Current: 372/6
• CPC Class Codes: G02B 6/0218 using mounting means, e.g. by using a combination of materials having different thermal expansion coefficients
• CPC Class Codes: H01S 3/04 Arrangements for thermal management
• CPC Class Codes: H01S 3/0405 Conductive cooling, e.g. by heat sinks or thermo-electric elements
• 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 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/094053 Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/1618 ytterbium

Abstract

Techniques and architecture are disclosed for controlling the temperature of a fiber laser system. In some embodiments, a single thermoelectric cooler (TEC) may be utilized to control the temperature of multiple system components. In some embodiments, a TEC may be physically/thermally coupled to a laser diode, which in turn may be physically/thermally coupled with a mounting plate to which one or more fiber grating holders are physically/thermally coupled, and an optical fiber that is operatively coupled with the laser diode may be physically/thermally coupled with the one or more fiber grating holders. In some embodiments, this may provide a thermal pathway/coupling between the optical fiber (e.g., its fiber grating(s)), and the TEC. In some embodiments, this may reduce/minimize the quantity of temperature control components, reduce system size/complexity, increase system dependability, and/or increase system performance/efficiency. Numerous configurations and variations will be apparent in light of this disclosure.

Claims

1. A system comprising:

a fiber laser comprising;

a laser diode; and

an optical fiber optically coupled with the laser diode, wherein the optical fiber includes a first fiber Bragg grating and a second fiber Bragg grating;

a thermal control component at least one of physically and thermally coupled with the laser diode; and

a first fiber grating holder comprising an elongate body of thermally conductive material having a first channel formed therein and configured to receive the first fiber Bragg grating of the optical fiber, wherein a depth of the first channel of the first fiber grating holder is greater than or equal to a diameter of the optical fiber, and wherein the first fiber grating holder is at least one of physically and thermally coupled with at least one of the laser diode and the thermal control component; and

a second fiber grating holder comprising an elongate body of thermally conductive material having a second channel formed therein and configured to receive the second fiber Bragg grating of the optical fiber, wherein a depth of the second channel of the second fiber grating holder is greater than or equal to the diameter of the optical fiber, and wherein the second fiber grating holder is at least one of physically and thermally coupled with at least one of the laser diode and the thermal control component.

2. The system of claim 1, wherein at least one of:

the laser diode comprises an ytterbium (Yb)-doped laser medium or a thulium (Tm)-doped laser medium; and

the optical fiber comprises at least one of a silica glass fiber, a phosphate glass fiber, a fluoride glass fiber, a chalcogenide glass fiber, and a germanate glass fiber.

3. The system of claim 1, wherein the thermal control component comprises a thermoelectric cooler, an air-cooled heat exchanger, or a water-cooled cold plate.

4. The system of claim 1, wherein at least one of the first and second channels is configured to receive a quantity of at least one of a thermally conductive epoxy and a thermally conductive thermoplastic/thermoset therein.

5. The system of claim 1, wherein the first fiber Bragg grating comprises a high-reflectivity fiber Bragg grating and the second fiber Bragg grating comprises a partial-reflectivity fiber Bragg grating.

6. The system of claim 5 further comprising a gain fiber operatively coupled to the optical fiber, wherein the gain fiber comprises a core that has been doped with a rare earth element, and wherein the gain fiber is disposed between the high-reflectivity fiber Bragg grating and the partial-reflectivity fiber Bragg grating of the optical fiber.

7. The system of claim 1 further comprising a heat spreader, wherein the heat spreader is:

at least one of physically and thermally coupled with the laser diode and the thermal control component; and

at least one of physically and thermally coupled with at least one of the first and second fiber grating holders.

8. The system of claim 7, wherein the heat spreader comprises an arrangement of foils comprising at least one of indium (In), copper (Cu), and an alloy thereof.

9. The system of claim 7 further comprising a mounting plate physically coupled with at least one of the first and second fiber grating holders and at least one of physically and thermally coupled with the heat spreader.

10. The system of claim 1 further comprising a mounting plate physically coupled with at least one of the first and second fiber grating holders and at least one of physically and thermally coupled with the laser diode.

25. The system of claim 7, wherein the heat spreader comprises a slab of at least one of steel, aluminum (Al), copper (Cu), diamond, and an alloy thereof.

11. A system comprising:

a fiber laser comprising;

a laser diode; and

an optical fiber optically coupled with the laser diode, wherein the optical fiber includes a high-reflectivity fiber Bragg grating, a partial-reflectivity fiber Bragg grating, and a gain fiber there between;

a thermoelectric cooler at least one of physically and thermally coupled with the laser diode;

a mounting plate thermally coupled with the thermoelectric cooler;

a first fiber grating holder at least one of physically and thermally coupled with the mounting plate, wherein the first fiber grating holder comprises an elongate body of thermally conductive material having a first channel formed therein, wherein the first channel is configured to receive the high-reflectivity fiber Bragg grating and to receive a quantity of at least one of a thermally conductive epoxy and a thermally conductive thermoplastic/thermoset therein, and wherein a depth of the first channel is greater than or equal to a diameter of the optical fiber; and

a second fiber grating holder at least one of physically and thermally coupled with the mounting plate, wherein the second fiber grating holder comprises an elongate body of thermally conductive material having a second channel formed therein, wherein the second channel is configured to receive the partial-reflectivity fiber Bragg grating and to receive a quantity of at least one of a thermally conductive epoxy and a thermally conductive thermoplastic/thermoset therein, and wherein a depth of the second channel is greater than or equal to the diameter of the optical fiber.

12. The system of claim 11 further comprising at least one of a holmium-doped yttrium aluminum garnet (Ho:

YAG) laser crystal and a non-linear converter configured to be optically pumped by the fiber laser.

13. A system comprising:

a fiber laser comprising;

a laser diode; and

an optical fiber optically coupled with the laser diode, the optical fiber including a fiber Bragg grating;

a fiber grating holder comprising an elongate body of thermally conductive material having a channel formed therein, the channel configured to receive the fiber Bragg grating of the optical fiber and having a depth greater than or equal to a diameter of the optical fiber;

a thermal control component thermally coupled with the laser diode and the fiber grating holder and configured to control the temperature of the laser diode and the fiber Bragg grating of the optical fiber; and

a heat spreader disposed between the thermal control component and the laser diode, wherein the heat spreader is;

physically coupled with the thermal control component and the laser diode; and

thermally coupled with the fiber grating holder, the laser diode, and the thermal control component.

14. The system of claim 13, wherein the heat spreader comprises a slab of at least one of steel, aluminum (Al), copper (Cu), diamond, and an alloy thereof.

15. The system of claim 13 further comprising a mounting plate, wherein the mounting plate is:

physically coupled with the laser diode and the fiber grating holder; and

thermally coupled with the fiber grating holder, the laser diode, and the thermal control component.

16. The system of claim 13, wherein the fiber grating holder is physically coupled with the heat spreader.

17. The system of claim 13, wherein the heat spreader comprises an arrangement of foils comprising at least one of indium (In), copper (Cu), and an alloy thereof.

18. The system of claim 13 further comprising a mounting plate, wherein the mounting plate is:

physically coupled with the heat spreader and the fiber grating holder; and

thermally coupled with the fiber grating holder, the heat spreader, and the thermal control component.

19. The system of claim 13 further comprising a quantity of at least one of a thermally conductive epoxy and a thermally conductive thermoplastic/thermoset disposed within the channel of the fiber grating holder having the fiber Bragg grating of the optical fiber therein.

20. The system of claim 13, wherein the laser diode comprises an ytterbium (Yb)-doped laser medium or a thulium (Tm)-doped laser medium.

21. The system of claim 13, wherein the optical fiber comprises at least one of a silica glass fiber, a phosphate glass fiber, a fluoride glass fiber, a chalcogenide glass fiber, and a germanate glass fiber.

22. The system of claim 13, wherein the thermal control component comprises a thermoelectric cooler, an air-cooled heat exchanger, or a water-cooled cold plate.

23. The system of claim 13, wherein the thermally conductive material of the fiber grating holder comprises at least one of a thermally conductive metal, a thermally conductive composite, and a thermally conductive ceramic.

24. The system of claim 13 further comprising at least one of a holmium-doped yttrium aluminum garnet (Ho:

YAG) laser crystal and a non-linear converter configured to be optically pumped by the fiber laser.