Honeywell International Inc.

Marc Smiciklas

Glen Aaron Sanders

Lee Kevin Strandjord

Tiequn Qiu

Jianfeng Wu

Norman Gerard Tarleton

Neil A Krueger

Robert Compton

Mary Salit

Mary K Salit

A method of operating a resonator optical gyroscope includes generating optical signals having a broadband frequency range. The method includes coupling the optical signals into an optical resonator (OR) to propagate in a first direction and coupling the optical signals out of the OR after the optical signals pass through the OR in the first direction. The method includes coupling optical signals into the OR to propagate in a second direction and coupling optical signals out of the OR after the optical signals pass through the OR in the second direction. The method includes amplifying the optical signals coupled out of the OR by the second optical coupler or the optical signals coupled out of the OR by the first optical coupler to generate amplified optical signals and generating electrical signals corresponding to the amplified optical signals. The method includes determining a rotation rate based on the electrical signals.

Broadband resonator optical gyroscope with efficient optical power management for low shot noise

Improvements to optical power regulation in a gyroscopic system are described. The system can include an optical assembly (e.g., optical bench) which couples opposing optical signals to a resonator coil. The system can monitor the power of the optical signals through the resonator coil by including signal extraction optics in the optical assembly which are configured to extract a portion of the optical signals. The portions can be extracted via a single beamsplitter, wherein the beamsplitter reflects the portions at a single common surface, and can also reflect the portions to a respective photodetector in free space free from intervening optical components, such as polarizers or beamsplitters. One or more processors can be coupled to the optical assembly, wherein the processor(s) are configured to adjust the power of the optical signals in response to detecting a power difference between the optical signals.

Systems and methods for enhanced optical power control

A resonator fiber optic gyroscope (RFOG) that includes at least one laser, a resonator and a resonator hopping control system is provided. The resonator is in operational communication with the at least one laser to receive a clockwise (CW) laser light and counterclockwise (CCW) laser light produced by the at least one laser. The resonance hopping control system is in communication with an output of the resonator and the at least one laser. The resonance hopping control system is configured to control an output of the at least one laser to periodically unlock, hop and lock frequencies of the laser light traveling in the CW and CCW directions in the resonator to resonance frequencies of the resonator to mitigate bias errors due to resonance asymmetries.

Gyroscope with reduced bias errors due to resonance asymmetries

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.

RFOG resonance hopping

Systems and methods for performing SHD switching for RFOGS are provided herein. A system includes a resonator in which light resonates; at least one laser source that produces first and second optical beams; heterodyne modulators that modulate the first and second optical beams at a heterodyne frequency plus a modulation frequency offset to produce multiple sideband optical beams, wherein the modulation frequency offset has a different sign for the first and second optical beams; a frequency switching controller that alternatingly switches the signs of the modulation frequency offset applied to the first and second optical beams, wherein the heterodyne modulation of the first and second optical beams are on average at the heterodyne frequency; at least one coupler that couples the sideband optical beams into the resonator; a feedback control that detects the sideband optical beams transmitted from the resonator and, in response, adjusts frequencies of the optical beams.

Sideband heterodyne switching for resonator fiber optic gyroscopes (RFOGs)

Techniques are provided for correcting for time varying changes to a gyroscope incorporating a resonator and/or to an environment in which the gyroscope is located, and which affect the resonator. Free spectral range of the gyroscope, which varies with such changes, is determined and is used to correct at least one of gyroscope bias and scale factor.

Systems and methods for correcting errors in gyroscopes

A hyperbolic modulation offset reducer circuit for a resonator fiber optic gyro (RFOG) is provided. The circuit includes a first demodulation circuit that is configured to demodulate a received transmission signal from a resonator at twice a sideband heterodyne detection modulation frequency to reject signals due to backscatter. A slave resonance tracking loop of the circuit is coupled to an output of the first demodulation circuit. The slave resonance tracking loop is configured to create an offset frequency signal from the transmission signal that is applied to an optical phase lock loop of a RFOG. A hyperbolic modulator offset control loop is also coupled to the output of the first demodulation circuit. The hyperbolic modulator offset control loop is configured to create a subharmonic common modulation signal from the transmission signal that is coupled to a common phase module in a silicon photonics chip of the RFOG.

Hyperbolic modulation offset error reducer for an RFOG

A resonance fiber-optic gyro (RFOG) with quadrature error reducer is provided. The RFOG with quadrature error reducer includes a laser assembly, a fiber resonator assembly, a resonance tracking loop and a quadrature error reducer circuit. The resonance tracking loop, coupled to an output of the finder resonator assembly, is used to generate a resonance frequency signal that is coupled to an OPLL mixer in one of a CCW OPLL or the CW OPLL of the laser assembly. The quadrature error reducer circuit includes an amplitude control loop and a second harmonic phase control loop. The amplitude control loop is used to generate a common modulation signal. An output of the amplitude control loop is coupled to a common phase modulator in the laser assembly. The second harmonic phase control loop is used to selectively adjust a phase of a second harmonic modulation signal in the amplitude control loop at startup.

Resonator fiber-optic gyro with quadrature error reducer

In one embodiment, a method is provided. The method comprises: spin polarizing alkali atoms in a cavity; shifting resonant frequencies of the cavity at a rate proportional to a magnitude of a magnetic field incident upon the cavity; reflecting modulated right hand circularly polarized light and modulated left hand circularly polarized light from the cavity; transforming the reflected modulated right hand circularly polarized light to reflected modulated vertically polarized light, and the reflected modulated left hand circularly polarized light to reflected modulated horizontally polarized modulated light; generating a first error signal having an amplitude proportional to the shift in a resonant frequency corresponding to the reflected modulated vertically polarized light and a sign indicative of whether a frequency of the reflected modulated vertically polarized light is above or below the corresponding resonant frequency; generating a second error signal having an amplitude proportional to the shift in a resonant frequency corresponding to the reflected modulated horizontally polarized light and a sign indicative of whether a frequency of the reflected modulated horizontally polarized light is above or below the corresponding resonant frequency; adjusting a carrier frequency of the modulated right hand circularly polarized light in response to the first error signal; adjusting a carrier frequency of the modulated left hand circularly polarized light in response to the second error signal; and generating a measured Larmor frequency.

System and method for a cavity magnetometer using a pound-drever-hall detector

Systems and methods for reducing polarization-related bias errors in RFOGS are described herein. In certain implementations, an RFOG system includes a fiber optic resonator, one or more laser sources, wherein light from the laser sources launches first and second optical beams into the fiber optic resonator in opposite directions, and an electro-optically tunable devices in the resonator path configured to modulate the phase difference between polarization components in the first and second optical beams as the optical beams propagate within the fiber optic resonator. The system further includes at least one photodetector, wherein the polarization components of the first and second optical beams are incident on the photodetector, wherein the at least one photodetector provides an electrical signal, and at least one processing unit configured to receive the electrical signal and calculate a rotation rate for the RFOG and provide a drive signal for the electro-optically tunable device.

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Phoenix, AZ, United States of America

Marc Smiciklas