Integrated optical gyroscope with noise cancellation

Patent metadata

Field	Value
Publication number	US-10495462-B2
Application number	US-201815993525-A
Country	US
Kind code	B2
Filing date	May 30, 2018
Priority date	May 30, 2017
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

An optical gyroscope includes, in part, an optical switch, a pair of optical rings and a pair of photodetectors. The optical switch supplies a laser beam. The first optical ring delivers a first portion of the beam in a clockwise direction during the first half of a period, and a first portion of the beam in a counter clockwise direction during the second half of the period. The second optical ring delivers a second portion of the beam in a counter clockwise direction during the first half of the period, and a second portion of the beam in a clockwise direction during the second half of the period. The first photodetector receives the beams delivered by the first and second optical rings during the first half of the period. The second photodetector receives the beams delivered by the first and second optical rings during the second half of the period.

First claim

What is claimed is:

1. An optical gyroscope comprising:
an optical switch adapted to deliver a laser beam to a first path during a first half of a period and to a second path during a second half of the period;
a first optical ring configured to deliver a first portion of the beam received from the first path in a clockwise direction during the first half of the period, and further to deliver a first portion of the beam received from the second path in a counter clockwise direction during the second half of the period;
a second optical ring configured to deliver a second portion of the beam received from the first path in a counter clockwise direction during the first half of the period, and further to deliver a second portion of the beam received from the second path in a clockwise direction during the second half of the period;
a first photodetector adapted to receive the beams delivered by the first and second optical rings during the first half of the period; and
a second photodetector adapted to receive the beams delivered by the first and second optical rings during the second half of the period.

2. The optical gyroscope of claim 1 further comprising:
a first trans-impedance amplifier adapted to amplify an output signal of the first photodetector by a first amplification value; and
a second trans-impedance amplifier adapted to amplify an output signal of the second photodetector by a second amplification value.

3. The optical gyroscope of claim 2 further comprising:
a first phase modulator adapted to delay a beam received or delivered by the first optical ring by a first predefined phase value.

4. The optical gyroscope of claim 3 wherein said first predefined phase value is a 90° phase value.

5. The optical gyroscope of claim 3 further comprising:
a signal combiner adapted to generate a first signal representative of a combined outputs of the first and second trans-impedance amplifiers.

6. The optical gyroscope of claim 5 further comprising:
a bandpass filter adapter to filter the first signal.

7. The optical gyroscope of claim 6 further comprising:
a mixer adapted to downconvert a frequency of the filtered first signal to generate a baseband signal.

8. The optical gyroscope of claim 7 further comprising:
a controller adapted to:
convert the baseband signal to a digital signal; and
generate a signal representative of a degree of rotation of the optical gyroscope about an axis in response to the digital signal.

9. The optical gyroscope of claim 5 wherein said signal combiner is adapted to add output signals of the first and second trans-impedance amplifiers.

10. The optical gyroscope of claim 9 wherein the second phase value is 90° phase value.

11. The optical gyroscope of claim 3 further comprising:
a second phase modulator adapted to delay a signal received or delivered by the second optical ring by a second predefined phase value.

12. The optical gyroscope of claim 1 wherein said first and second optical rings are ring resonators.

13. The optical gyroscope of claim 12 wherein each of the first and second ring resonators comprises one or more heating elements adapted to tune the resonator.

14. The optical gyroscope of claim 12 wherein the one or more heating elements are resistive heating elements integrated with the first and second ring resonators.

15. The optical gyroscope of claim 1 wherein said optical switch comprises a Mach Zehnder interferometer.

16. A method of determining a degree of orientation about an axis, the method comprising:
delivering a laser beam to a first path during a first half of a period and to a second path during a second half of the period;
delivering a first portion of the beam received from the first path to a first optical ring in a clockwise direction during the first half of the period;
delivering a first portion of the beam received from the second path to the first optical ring in a counter clockwise direction during the second half of the period;
delivering a second portion of the beam received from the first path to a second optical ring in a counter clockwise direction during the first half of the period;
delivering a second portion of the beam received from the second path to the second optical ring in a clockwise direction during the second half of the period;
detecting the beams delivered by the first and second optical rings during the first half of the period to generate a first signal; and
detecting the beams delivered by the first and second optical rings during the second half of the period to generate a second signal.

17. The method of claim 16 further comprising:
amplifying the first signal by a first amplification value to generate a first amplified signal; and
amplifying the second signal by a second amplification value to generate a second amplified signal.

18. The method of claim 17 further comprising:
delaying a beam received or delivered by the first optical ring by a first predefined phase value.

19. The method of claim of claim 18 wherein said first predefined phase value is a 90° phase value.

20. The method of claim 18 further comprising:
combining the first and second amplified signals to generate a combined signal.

21. The method of claim 20 further comprising:
filtering the combined signal to generate a filtered signal.

22. The method of claim 21 further comprising:
downconverting a frequency of the filtered signal to generate a baseband signal.

23. The method of claim 22 further comprising:
converting the baseband signal to a digital signal; and
generating a value representative of a degree of rotation of the optical gyroscope about an axis in response to the digital signal.

24. The method of claim 20 wherein the combining of the first and second amplified signals comprises adding the first and second amplified signals.

25. The method of claim 18 further comprising:
delaying a beam received or delivered by the second optical ring by a second predefined phase value.

26. The method of claim 25 wherein said second predefined phase value is a 90° phase value.

27. The method of claim 16 wherein said first and second optical rings are ring resonators.

28. The method of claim 27 further comprising:
tuning the first and second ring resonators by applying heat.

Assignees

• California Inst Of Techn

Inventors

• Khial Parham Porsandeh
• Hajimiri Seyed Ali

Classifications

• G01C19/727

  using a passive ring resonator · CPC title

• G01C19/722 Primary

  of the mechanical construction · CPC title

• G01C19/64

  Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams · CPC title