Temperature control system for a frequency converted diode laser

• US 7,899,105 B1
• Filed: 06/15/2006
• Issued: 03/01/2011
• Est. Priority Date: 06/15/2005
• Status: Active Grant

• Current Assignee: Idex Health & Science LLC (RELX PLC)
• Original Assignee: CVI Laser LLC
• Inventors: Paterson, Scott, Vadnais, Neil E., Hargis, David E., Takeuchi, Eric B., O'Shaughnessy, John
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): FORDE, DELMA ROSA
• Application Number:
  US11/455,223
• Time in Patent Office: 1,720 Days
• Field of Search: 372/92, 372/102
• US Class Current: 372/102
• CPC Class Codes: G02F 1/3775 with a periodic structure, e.g. domain inversion, for quasi-phase-matching [QPM] G02F1/383 takes precedence
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 5/0092 for nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity
• CPC Class Codes: H01S 5/024 Arrangements for thermal management
• CPC Class Codes: H01S 5/02415 by using a thermo-electric cooler [TEC], e.g. Peltier element
• CPC Class Codes: H01S 5/02446 Cooling being separate from the laser chip cooling
• CPC Class Codes: H01S 5/0612 controlled by temperature
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/146 using a fiber as external cavity

Abstract

Apparatus and methods of controlling a frequency-converted diode laser system are disclosed. The diode laser systems can include embodiments of thermally coupled elements facilitating temperature stabilization. Aspects of some methods include monitoring the output of a stabilized diode laser system to reduce noise of the output laser beam. Other aspects of some methods include adjusting the temperature of a frequency converter based on noise in the output beam, and/or the current provided to drive the diode laser. Systems incorporating such control aspects, and others, are also disclosed.

Claims

1. A frequency converted laser system, comprising:

a laser system comprising

a semiconductor gain medium,

a first reflective end disposed to form one end of a laser cavity,

an optical medium comprising an optical fiber and a fiber Bragg grating, the optical medium optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity,

wherein said laser system produces a laser beam output at a first frequency;

a waveguide comprising a nonlinear element, said waveguide optically coupled with the optical medium to receive the laser beam output of said laser system, said waveguide configured to output a laser beam having a second, different frequency;

a temperature controlled element; and

a thermal connector comprising a metal mesh surrounding at least a portion of said optical fiber including said Bragg grating, the thermal connector connected to said temperature controlled element, said thermal connector thermally coupled to said Bragg grating and said temperature controlled element such that the temperature of said Bragg grating is controlled by said temperature controlled element.

2. The frequency converted laser system of claim 1, wherein said temperature controlled element comprises a thermo-electric cooler.

3. The frequency converted laser system of claim 1, wherein said temperature controlled element comprises a housing enclosing at least a portion of said frequency converted laser system.

14. The frequency converted system of claim 1, wherein said mesh comprises copper, gold, silver, iron, aluminum, or alloys thereof.

15. The frequency converted system of claim 1, wherein said mesh is braided around said optical fiber and comprises a tail portion that is connected to said temperature controlled element.

4. A frequency converted laser system, comprising:

a laser system comprising

a semiconductor gain medium,

a first reflective end disposed to form one end of a laser cavity,

an optical medium comprising a Bragg grating optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity,

wherein said laser system produces a laser beam output at a first frequency;

a waveguide comprising a nonlinear element, said waveguide optically coupled with the optical medium to receive the laser beam output of said laser system, said waveguide configured to output a laser beam having a second, different frequency;

a temperature controlled element; and

a thermal connector connected to said temperature controlled element, said thermal connector surrounding said Bragg grating and thermally coupled to said Bragg grating, said thermal connector configured to thermally couple said temperature controlled element and said Bragg grating such that the temperature of said Bragg grating is controlled by said temperature controlled element,

wherein said optical medium comprises an optical fiber, wherein said Bragg grating comprising a fiber Bragg grating formed in a portion of said optical fiber, and wherein said thermal connector comprises a metal envelope having a cavity therein and enclosing at least a portion of said optical fiber comprising said fiber Bragg grating within the cavity.

5. The frequency converted laser system of claim 4, wherein said envelope is configured to form a cavity enclosing said at least a portion of said optical fiber comprising said fiber Bragg grating, said envelope comprising an entrance aperture and an exit aperture configured such that said optical fiber passes through said entrance aperture and said exit aperture.

6. The frequency converted laser system of claim 4, wherein said envelope comprises metal foil less than or equal to about 3 mils thick.

7. A frequency converted laser system, comprising:

a laser system comprising

a semiconductor gain medium,

a first reflective end disposed to form one end of a laser cavity,

an optical medium comprising a Bragg grating optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity, wherein said laser system produces a laser beam output at a first frequency;

a waveguide comprising a nonlinear element, said waveguide optically coupled with the optical medium to receive the laser beam output of said laser system, said waveguide configured to output a laser beam having a second, different frequency;

a temperature controlled element; and

a thermal connector connected to said temperature controlled element and coupled to at least a portion of said optical medium having said Bragg grating, said thermal connector configured to thermally couple said temperature controlled element and said Bragg grating such that the temperature of said Bragg grating is controlled by said temperature controlled element,

wherein said optical medium comprises an optical fiber, wherein said Bragg grating comprises a fiber Bragg grating formed in a portion of said optical fiber, and wherein said thermal connector comprises a metal envelope forming a cavity, the envelope surrounding at least a portion of said optical fiber comprising said fiber Bragg grating disposed within the cavity,

wherein said envelope comprises

a base portion comprising a surface disposed in mechanical contact with said temperature controlled element; and

a jacket portion attached to said base portion, the jacket portion connected to said base portion and configured to form the cavity between said base portion and said jacket portion.

8. A frequency converted laser system, comprising:

a laser system comprising

a semiconductor gain medium,

a first reflective end disposed to form one end of a laser cavity,

an optical medium comprising a Bragg grating optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity, wherein said laser system produces a laser beam output at a first frequency;

a waveguide comprising a nonlinear element, said waveguide optically coupled with the optical medium to receive the laser beam output of said laser system, said waveguide configured to output a laser beam having a second, different frequency;

a temperature controlled element; and

a thermal connector connected to said temperature controlled element and coupled to at least a portion of said optical medium having said Bragg grating, said thermal connector configured to thermally couple said temperature controlled element and said Bragg grating such that the temperature of said Bragg grating is controlled by said temperature controlled element,

wherein said optical medium comprises an optical fiber, wherein said Bragg grating comprises a fiber Bragg grating formed in a portion of said optical fiber, and wherein said thermal connector comprises a metal envelope having a cavity, said envelope surrounding at least a portion of said optical fiber comprising said fiber Bragg grating, and

wherein said envelope comprises

a jacket, and

an insulator covering at least a portion of said jacket.

9. The frequency converted laser system of claim 8, wherein at least a portion of said base portion of said envelope is thicker than a portion of said jacket portion of said envelope.

10. A method of manufacturing a frequency converted laser system having a laser system that includes a semiconductor gain medium, a first reflective end disposed to form one end of a laser cavity, an optical medium comprising a Bragg grating optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity, a waveguide comprising a nonlinear element, and a temperature controlled element, comprising:

forming a thermal connector comprising a metal mesh around at least a portion of said optical fiber comprising the fiber Bragg grating to surround said Bragg grating, the thermal covering configured to transfer heat between the fiber Bragg grating and the thermal connector; and

coupling the thermal connector to the temperature controlled element such that thermal conduction occurs between the fiber Bragg grating and the temperature controlled element such that the temperature of the fiber Bragg grating is controlled by said temperature controlled element.

11. A method of manufacturing a frequency converted laser system having a laser system that includes a semiconductor gain medium, a first reflective end disposed to form one end of a laser cavity, an optical medium comprising a Bragg grating optically coupled to receive an optical output of the semiconductor gain medium, said Bragg grating forming a second reflective end of the laser cavity, a waveguide comprising a nonlinear element, and a temperature controlled element, comprising:

forming a thermal connector around at least a portion of said optical fiber comprising the fiber Bragg grating to surround said Bragg grating, said thermal connector comprising a metal envelope having a cavity, said envelope surrounding at least a portion of said optical fiber comprising said fiber Bragg grating that is disposed within the cavity, the thermal covering configured to transfer heat between the fiber Bragg grating and the thermal connector; and

coupling the thermal connector to the temperature controlled element such that thermal conduction occurs between the fiber Bragg grating and the temperature controlled element such that the temperature of the fiber Bragg grating is controlled by said temperature controlled element.

12. A frequency converted system, comprising:

a laser diode system comprising a fiber Bragg grating; and

a means for controlling the temperature of said fiber Bragg grating through thermal conduction, wherein said temperature controlling means surrounds said fiber Bragg grating and controls the temperature of said fiber Bragg grating,

wherein said temperature controlling means comprises a metal mesh thermal connector coupled to said fiber Bragg grating, said thermal connector is configured to be connectable to a temperature controlled element such that the temperature of said Bragg grating is controlled by said temperature controlled element.

13. A frequency converted system, comprising:

a laser diode system comprising a fiber Bragg grating; and

a means for controlling the temperature of said fiber Bragg grating through thermal conduction, wherein said temperature controlling means surrounds said fiber Bragg grating and controls the temperature of said fiber Bragg grating,

wherein said temperature controlling means comprises a metal envelope having a cavity, said envelope surrounding at least a portion of said fiber Bragg grating, wherein said temperature controlling mean is configured to be connectable to a temperature controlled element such that the temperature of said Bragg grating is controlled by said temperature controlled element.