Abstract: 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.

Abstract: 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 beamplitters. 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

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.

Abstract: 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.

Abstract: 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.

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.

Abstract: 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.

Abstract: A system, feedback controller and method are disclosed. For example, the feedback controller includes a phase-sensitive quadrature controller configured to generate a first control signal associated with a controlled signal, a phase-sensitive in-phase controller configured to generate a second control signal associated with the controlled signal, a summer configured to add the first control signal and the second control signal, and a subtractor configured to subtract the summed first and second control signals from an uncontrolled signal.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In one embodiment, a method is provided.

Abstract: 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.

Abstract: 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.

Abstract: In one embodiment, a method is provided.