Frequency stabilized laser system

• US 8,736,845 B2
• Filed: 04/27/2012
• Issued: 05/27/2014
• Est. Priority Date: 05/24/2011
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wu, Jianfeng, Strabley, Jennifer S., Qiu, Tiequn, Sanders, Glen A.
• Primary Examiner(s): Lyons, Michael A
• Application Number:
  US13/457,929
• Publication Number:
  US 20120300198A1
• Time in Patent Office: 760 Days
• Field of Search: 356/460, 356/461, 372/29.02, 372/32
• US Class Current: 356/461
• CPC Class Codes: G03F 7/70525 Controlling normal operating mode, e.g. matching different apparatus, remote control or prediction of failure
• CPC Class Codes: H01S 5/06258 with DFB-structure
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

A laser stabilization system includes laser source having first and second ends; first waveguide portion having first and second ends, first end of first waveguide portion coupled to first end of laser source; second waveguide portion having first and second ends, first end of second waveguide portion coupled to second end of laser source; micro-cavity coupled between second end of first waveguide portion and second end of second waveguide portion, micro-cavity having resonant frequency; and electronic locking loop coupled between micro-cavity and laser source, wherein electronic locking loop electronically locks laser source to resonant frequency of micro-cavity; wherein first waveguide portion is optical locking loop coupled between micro-cavity and laser source, wherein optical locking loop optically locks laser source to resonant frequency of micro-cavity; micro-cavity stabilization loop coupled with micro-cavity, wherein micro-cavity stabilization loop stabilizes resonant frequency of micro-cavity to reference frequency; and output for outputting light from system.

Claims

1. A laser stabilization system comprising:

a laser source having a first end and a second end;

a first waveguide portion having a first end and a second end, the first end of the first waveguide portion coupled to the first end of the laser source;

a second waveguide portion having a first end and a second end, the first end of the second waveguide portion coupled to the second end of the laser source;

a micro-cavity coupled between the second end of the first waveguide portion and the second end of the second waveguide portion, the micro-cavity having a resonant frequency;

an electronic locking loop coupled between the micro-cavity and the laser source, wherein the electronic locking loop electronically locks the laser source to the resonant frequency of the micro-cavity;

wherein the first waveguide portion is an optical locking loop coupled between the micro-cavity and the laser source, wherein the optical locking loop optically locks the laser source to the resonant frequency of the micro-cavity;

a micro-cavity stabilization loop coupled with the micro-cavity, wherein the micro-cavity stabilization loop stabilizes the resonant frequency of the micro-cavity to a reference frequency; and

an output for outputting light from the laser stabilization system.

2. The system of claim 1, wherein the micro-cavity stabilization loop includes a thermal phase modulator coupled to the micro-cavity, wherein the thermal phase modulator receives a feedback signal that varies based on an absorption line measurement of a laser beam emitted from the micro-cavity through a gas chamber.

3. The system of claim 2, wherein the micro-cavity stabilization loop further includes:

a gas chamber having an absorption line coupled to the micro-cavity; and

a photo detector coupled to the gas chamber;

wherein the photo detector measures the intensity of the laser beam emitted from the micro-cavity after it passes through the gas chamber;

wherein the feedback signal varies based on the intensity; and

wherein change in the intensity is indicative of a change in the resonant frequency of the micro-cavity.

4. The system of claim 1, wherein the micro-cavity stabilization loop thermally stabilizes the micro-cavity against thermal noise.

5. The system of claim 1, wherein the laser source is a single frequency laser.

6. The system of claim 5, wherein the laser source is a multi-electrode distributed-feedback laser.

7. The system of claim 1, wherein the micro-cavity is a passive micro-ring cavity with a quality factor (Q) of above approximately 10^7.

8. The system of claim 1, wherein the micro-cavity is either a micro-disk or a micro-ring.

9. The system of claim 1, wherein the electronic locking loop comprises a Pound-Drever-Hall locking loop.

10. The system of claim 1, wherein the electronic locking loop electronically locks the laser source to the resonant frequency by injection-current induced electro-optical effect.

11. A method of stabilizing a laser comprising:

optically locking the laser to a resonant frequency of a micro-cavity using an optical locking loop;

electronically locking the laser to the resonant frequency of a micro-cavity using an electronic locking loop; and

stabilizing the resonant frequency of the micro-cavity to a reference frequency using a micro-cavity stabilization loop.

12. The method of claim 11, wherein stabilizing the resonant frequency of the micro-cavity includes adjusting an optical path of the micro-cavity cavity based on an error signal received from an absorption line measurement of a laser beam from the micro-cavity.

13. The method of claim 11, wherein stabilizing the resonant frequency of the micro-cavity includes:

passing a laser beam from the micro-cavity through a gas chamber having an absorption line;

detecting the intensity of the laser beam from the micro-cavity after it is passed through the gas chamber having the absorption line; and

adjusting an optical path of the micro-cavity using a thermal phase modulator based on the intensity of the laser beam after it is passed through the gas chamber having the absorption line.

14. The method of claim 11, wherein optically locking the laser to the resonant frequency further comprises:

optically modulating the phase of the laser in a self-injection locking loop.

15. The method of claim 11, wherein electronically locking the laser to the resonant frequency further comprises:

electronically modulating the direct current in a Pound-Drever-Hall locking loop.

16. The method of claim 11, wherein stabilizing the resonant frequency of the micro-cavity to a reference frequency using a micro-cavity stabilization loop comprises:

thermally stabilizing the micro-cavity against thermal noise.

17. A fiber optic gyroscope comprising:

a fiber optic coil; and

a micro-cavity frequency stabilized laser system coupled to the fiber optic coil, the micro-cavity frequency stabilized laser system comprising;

a laser source having a first end and a second end;

a first waveguide portion having a first end and a second end, the first end of the first waveguide portion coupled to the first end of the laser source;

a second waveguide portion having a first end and a second end, the first end of the second waveguide portion coupled to the second end of the laser source;

a micro-cavity coupled between the second end of the first waveguide portion and the second end of the second waveguide portion, the micro-cavity having a resonant frequency;

an electronic locking loop coupled between the micro-cavity and the laser source, wherein the electronic locking loop electronically locks the laser source to the resonant frequency of micro-cavity;

wherein the first waveguide portion is an optical locking loop coupled between the micro-cavity and the laser source, wherein the optical locking loop optically locks the laser source to the resonant frequency of the micro-cavity;

a micro-cavity stabilization loop coupled with the micro-cavity, wherein the micro-cavity stabilization loop stabilizes the resonant frequency of the micro-cavity to a reference frequency; and

an output for outputting light from the laser stabilization system.

18. The gyroscope of claim 17, wherein the micro-cavity stabilization loop includes a thermal phase modulator coupled to the micro-cavity, wherein the thermal phase modulator receives a feedback signal that varies based on an absorption line measurement of a laser beam emitted from the micro-cavity.

19. The gyroscope of claim 17, wherein the electronic locking loop comprises a Pound-Drever-Hall locking loop.

20. The gyroscope of claim 17, wherein the electronic locking loop electronically locks the laser source to the resonant frequency by injection-current induced electro-optical effect.