Gyroscopes based on optomechanical sensing
Gyroscopes based on optomechanical designs to provide sensitive sensing while providing relatively large bandwidth and dynamic range with enhanced noise performance.
1. A gyroscope, comprising:
a vibrating mass;
a driving oscillator coupled to the vibrating mass to drive the vibrating mass to oscillate along a driving axis;
a sensing oscillator coupled to the vibrating mass to allow the vibrating mass to oscillate along a sensing axis that is different from the driving axis, the sensing oscillator including (1) a sensing mechanical oscillator coupled to the vibrating mass to cause the vibrating mass to oscillate along the sensing axis and (2) a sensing optical resonator coupled to the vibrating mass to respond to an oscillation of the vibrating mass to modulate an optical resonance of the sensing optical resonator;
a laser that produces a laser light beam at a laser frequency that is detuned from and is less than the optical resonance of the sensing optical resonator to cause a transfer of energy from the sensing mechanical oscillator to the sensing optical resonator; and
a sensing mechanism that measures modulated light in the sensing optical resonator indicating a motion of the vibrating mass along the sensing axis to obtain rotation information of the gyroscope based on coupling between the sensing oscillator and the driving oscillator caused by rotation of the gyroscope.
2. The gyroscope as in claim 1 , wherein:
the sensing optical resonator is an optical Fabry-Perot resonator formed of two mirrors and one of the two mirrors is coupled to, and moves with, the vibrating mass to change the optical resonance of the optical Fabry-Perot resonator as the coupled mirror moves with the vibrating mass.
3. The gyroscope as in claim 1 , wherein:
the sensing mechanical oscillator of the sensing oscillator includes a spring loaded mechanical oscillator.
4. The gyroscope as in claim 1 , wherein:
the driving oscillator includes a spring-loaded mechanical oscillator and an electrostatic drive that drives the spring-loaded mechanical oscillator to oscillate along the driving axis.
5. The gyroscope as in claim 1 , wherein:
the driving oscillator includes:
a spring-loaded mechanical oscillator coupled to the vibrating mass to cause the vibrating mass to oscillate along the driving axis; and
a driving optical resonator coupled to the vibrating mass and operable to receive a pump laser beam from the laser at the laser frequency, wherein the driving optical resonator is set to an optical resonance that is detuned from and is lower than the laser frequency to cause a transfer of energy from the driving optical resonator to the spring-loaded mechanical oscillator to drive the vibrating mass to oscillate along the driving axis.
6. The gyroscope as in claim 1 , wherein:
the driving oscillator includes:
a spring-loaded mechanical oscillator coupled to the vibrating mass to cause the vibrating mass to oscillate along the driving axis; and
a driving optical resonator coupled to the vibrating mass and operable to receive a pump laser light beam at a pump laser frequency that is detuned from and is higher than an optical resonance of the driving optical resonator to cause a transfer of energy from the driving optical resonator to the spring-loaded mechanical oscillator to drive the vibrating mass to oscillate along the driving axis.
7. The gyroscope as in claim 6 , comprising:
a pump laser that produces the pump laser light beam.
8. The gyroscope as in claim 1 , wherein:
the sensing mechanism includes an optical detector that is located to receive the modulated light output by the sensing optical resonator.
9. The gyroscope as in claim 1 , wherein:
the sensing mechanism includes:
an optical detector that is located to receive both the modulated light output by the sensing optical resonator and a portion of the laser light beam from the laser at the laser frequency to effectuate a homodyne detection indicates a motion of the vibrating mass.
10. The gyroscope as in claim 1 , wherein:
the sensing optical resonator includes an optical ring resonator.
11. The gyroscope as in claim 1 , wherein:
the sensing optical resonator of the sensing oscillator includes a sensing optical ring resonator;
the driving oscillator includes a driving optical ring resonator coupled to the vibrating mass and operable to receive a pump laser beam at a pump laser frequency that is detuned from and is higher than an optical resonance of the driving optical ring resonator to cause a transfer of energy from the driving optical ring resonator to the vibrating mass to oscillate along the driving axis.
12. The gyroscope as in claim 11 , wherein:
the driving optical ring resonator and the sensing optical ring resonator are mechanically coupled to each other.
13. The gyroscope as in claim 1 , wherein:
the vibrating mass, the driving oscillator, the sensing oscillator including the sensing optical resonator, the laser and the sensing mechanism are configured as a MEMS.
14. A method for operating a gyroscope to measure a rotation, comprising:
coupling a vibrating mass to both a driving oscillator that oscillates along a driving axis and a sensing oscillator that oscillates along a sensing axis which is different from the driving axis, wherein the sensing oscillator includes a sensing optical resonator coupled to the vibrating mass to respond to motion of the vibrating mass along the sensing axis to change an optical resonance of the sensing optical resonator;
operating the driving oscillator to drive the vibrating mass to oscillate along the driving axis;
operating the sensing oscillator coupled to the vibrating mass to receive energy coupled from the driving oscillator due to rotation of the gyroscope to cause the vibrating mass to oscillate along the sensing axis and to modulate the optical resonance of the sensing optical resonator;
coupling a laser light beam at a laser frequency that is detuned from and is less than the optical resonance of the sensing optical resonator into the sensing optical resonator to cause a transfer of energy from the vibrating mass to the sensing optical resonator; and
measuring a modulated light beam coupled out of the sensing optical resonator indicating a motion of the vibrating mass along the sensing axis to obtain rotation information of the gyroscope.
15. The method as in claim 14 , wherein:
the sensing optical resonator is an optical Fabry-Perot resonator formed of two mirrors and one of the two mirrors is coupled to, and moves with, the vibrating mass to change the optical resonance of the optical Fabry-Perot resonator as the coupled mirror moves with the vibrating mass.
16. The method as in claim 14 , wherein:
the sensing oscillator includes a sensing mechanical oscillator coupled to the vibrating mass to cause the vibrating mass to oscillate along the sensing axis, and
the sensing mechanical oscillator of the sensing oscillator includes a spring loaded mechanical oscillator.
17. The method as in claim 14 , comprising:
operating an electrostatic driver as part of the driving oscillator to drive the vibrating mass to oscillate along the driving axis.
18. The method as in claim 14 , comprising:
operating an optical resonator in the driving oscillator to transfer optical energy in the optical resonator to the vibrating mass to drive the vibrating mass to oscillate along the driving axis.
19. The method as in claim 18 , wherein:
the driving oscillator includes a spring-loaded mechanical oscillator coupled to the vibrating mass to cause the vibrating mass to oscillate along the driving axis; and
the optical resonator in the driving oscillator is operable to receive a pump laser beam at a pump laser frequency that is detuned from and is higher than an optical resonance of the optical resonator to cause the transfer of the optical energy to the spring-loaded mechanical oscillator.
20. The method as in claim 14 , comprising:
operating a laser to produce the laser light beam at the laser frequency that is coupled into the sensing optical resonator; and
directing a portion of the laser light beam from the laser and the modulated light beam output by the sensing optical resonator into an optical detector to effectuate a homodyne detection indicates a motion of the vibrating mass.