RFOG resonance hopping

Patent metadata

Field	Value
Publication number	US-11002544-B2
Application number	US-202016734038-A
Country	US
Kind code	B2
Filing date	Jan 3, 2020
Priority date	Jul 26, 2019
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

Systems and methods for performing resonator fiber optic gyroscope (RFOG) resonance hopping are described herein. For example, an RFOG includes a fiber optic resonator. The RFOG also includes a plurality of laser sources that each launch a respective laser for propagation within the fiber optic resonator. Further, the RFOG includes a threshold detector that determines when the operation of at least one laser source in the plurality of laser sources exceeds a threshold associated with the operational range of an aspect of the at least one laser source. Additionally, the RFOG includes a hop control logic that adjusts the frequency of at least one laser produced by the at least one laser source one or more resonant modes of the fiber optic resonator such that the aspect of the at least one laser moves away from the threshold towards a nominal value within the operational range.

First claim

What is claimed is:

1. A resonator fiber optic gyroscope (RFOG) comprising:
a fiber optic resonator;
a plurality of laser sources that each launch a respective laser for propagation within the fiber optic resonator;
a threshold detector that determines when the operation of at least one laser source in the plurality of laser sources exceeds a threshold associated with the operational range of an aspect of the at least one laser source; and
a hop control logic that adjusts the frequency of at least one laser produced by the at least one laser source one or more resonant modes of the fiber optic resonator such that the aspect of the at least one laser moves away from the threshold towards a nominal value within the operational range.

2. The RFOG of claim 1 , wherein the hop control logic further:
directs one or more control loops for the at least one laser to open when the frequency of the at least one laser is adjusted; and
directs the one or more control loops to close when frequency of the at least one laser is associated with the operational range of the aspect of the at least one laser.

3. The RFOG of claim 2 , wherein a control loop in the one or more control loops is a Pound Dreyer Hall control loop.

4. The RFOG of claim 1 , wherein the aspect of the at least one laser sources comprises at least one of:
a current provided to the at least one laser source;
a temperature associated with the at least one laser source; and
a frequency of light produced by the at least one laser source.

5. The RFOG of claim 1 , comprising a first offset configured to provide a nominal starting value for the aspect of the at least one laser source.

6. The RFOG of claim 1 , comprising a second offset set by the hop control logic, wherein the hop control logic sets the second offset to the nominal value for the aspect of the at least one laser source.

7. The RFOG of claim 1 , wherein the hop control logic comprises a memory that stores information associated with the adjustments of the frequency of the at least one laser over the one or more resonant modes of the fiber optic resonator.

8. The RFOG of claim 7 , wherein the information stored in the memory comprises:
temperature information;
current information;
the number of resonant modes through which the frequency of the at least one laser was adjusted; and
frequency information.

9. A method comprising:
propagating a plurality of lasers within a fiber optic resonator, wherein a plurality of control loops respectively associated with the plurality of lasers controls the respective frequency for the plurality of lasers to be at a resonant mode of the fiber optic resonator;
detecting that an aspect of at least one laser in the plurality of lasers has exceeded a threshold within the operational range of the aspect of the at least one laser;
opening a control loop in the plurality of control loops associated with the at least one laser;
change the frequency of the at least one laser one or more resonant modes such that the aspect of the at least one laser moves away from the threshold towards a nominal value within the operational range; and
closing the control loop such that the frequency of the at least one laser locks on a resonant frequency of the fiber optic resonator.

10. The method of claim 9 , wherein the control loop is a Pound Dreyer Hall control loop.

11. The method of claim 9 , wherein the aspect of the at least one laser source comprises at least one of:
a current provided to the at least one laser source;
a temperature associated with the at least one laser source; and
a frequency of light produced by the at least one laser source.

12. The method of claim 9 , further comprising setting the aspect of the at least one laser to a first offset that provides a nominal starting value for the aspect of the at least one laser source.

13. The method of claim 9 , wherein the nominal value is dictated by a second offset.

14. The method of claim 13 , wherein the second offset is controlled by a hop control logic.

15. The method of claim 9 , further comprising storing information associated with the adjustments of the frequency of the at least one laser over the one or more resonant modes of the fiber optic resonator in memory.

16. The method of claim 15 , wherein the information stored in the memory comprises:
temperature information;
current information;
the number of resonant modes through which the frequency of the at least one laser was adjusted; and
frequency information.

17. A system comprising:
a fiber optic resonator;
a plurality of laser sources that each launch a respective laser for propagation within the fiber optic resonator;
one or more control loops that change the frequency of the respective lasers produced by the plurality of laser sources to stay on resonant modes of the fiber optic resonator;
a threshold detector that determines when the operation of at least one laser source in the plurality of laser sources exceeds a threshold associated with the operational range of an aspect of the at least one laser source; and
a hop control logic that adjusts the frequency of at least one laser produced by the at least one laser source one or more resonant modes of the fiber optic resonator such that the aspect of the at least one laser moves away from the threshold towards a nominal value within the operational range.

18. The system of claim 17 , wherein the hop control logic further:
directs the one or more control loops for the at least one laser to open when the frequency of the at least one laser is adjusted; and
directs the one or more control loops to close when frequency of the at least one laser is associated with the operational range of the aspect of the at least one laser.

19. The system of claim 17 , comprising:
a first offset configured to provide a nominal starting value for the aspect of the at least one laser source,
a second offset set by the hop control logic, wherein the hop control logic sets the second offset to the nominal value for the aspect of the at least one laser source.

20. The system of claim 17 , wherein the hop control logic comprises a memory that stores information associated with the adjustments of the frequency of the at least one laser over the one or more resonant modes of the fiber optic resonator.

Assignees

• Honeywell Int Inc

Inventors

• Strandjord Lee K
• Smiciklas Marc
• Wu Jianfeng
• Sanders Glen A

Classifications

• H01S5/0612

  controlled by temperature · CPC title

• H01S5/0687

  Stabilising the frequency of the laser · CPC title

• G01C19/72 Primary

  with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers · CPC title

• H01S5/4068

  with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers · CPC title

• G01C19/721

  Details, e.g. optical or electronical details · CPC title