Abstract: Lower noise and complexity techniques are disclosed for compensating for time varying phase changes in fiber optics in a resonant fiber optic gyroscope (RFOG). Orthogonal components derived from an electrical beat note signal and a difference between clockwise and counterclockwise resonant frequencies of an optical resonator coil of the RFOG are determined. The orthogonal products are converted to a phase which is differentiated with respect to time to obtain a beat note correction signal.

Abstract: An RFOG includes a resonator and an optical signal source configured to produce optical signals. Further, the RFOG includes optical components that introduce a first and second optical signals derived from the optical signals for propagation within the resonator wherein the first and second optical signals propagate in opposite directions. Additionally, the RFOG includes serrodyne modulation electronics that generate a serrodyne modulation control signal, wherein a first and second serrodyne modulation signal are generated from the serrodyne modulation control signal, wherein a sign of a slope of the first serrodyne modulation signal is opposite a sign of a slope of the second serrodyne modulation signal, wherein the signs of the slopes of the first and second serrodyne modulation signals periodically switch.

Abstract: Embodiments utilize an optical frequency comb generator coupled to an optical resonator of an optical gyroscope. The optical frequency comb generator generates an optical frequency comb having frequency peaks that each correspond to a respective resonance frequency of the optical resonator. A control servo can be coupled to the optical frequency comb generator and controls the optical frequency comb output from the optical frequency comb generator. In doing so, the optical frequency comb remains tuned to the resonance frequencies of the optical resonator during gyroscope operation.

Abstract: 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.

Abstract: A method is provided that includes combining a light wave from a master laser with a light wave from a first slave laser to produce a first signal including a first beat note signal, detecting the first signal, providing the first signal to a first mixer in a feedback path of a first optical phase lock loop, receiving a signal from a first offset frequency source at the first mixer, applying a first notch filter in the feedback path of the first optical phase lock loop after the first mixer to remove mixer products from an output of the first mixer, locking a frequency of the light wave from the master laser to a resonant frequency of a fiber optic resonator, and phase locking the first slave laser to the frequency of the master laser in the first optical phase lock loop at a first offset frequency.

Abstract: A gyroscope comprises first and second light sources that emit first and second beams with broadband spectrums, and a waveguide arrangement that communicates with the light sources. A resonator communicates with the waveguide arrangement to receive the beams. A first circulator is coupled to the waveguide arrangement between the first light source and the resonator. A second circulator is coupled to the waveguide arrangement between the second light source and the resonator. A first rate detector communicates with the resonator through the first circulator, and a second rate detector communicates with the resonator through the second circulator. The rate detectors produce rate measurements based on a detected resonance frequency shift of the beams in the resonator caused by rotation of the gyroscope. Outputs of the rate detectors are used to calculate a rotation rate that is corrected for errors due to a time varying pathlength change in the resonator.

Abstract: Various examples of a closed-loop optical gyroscope are disclosed. The closed-loop optical gyroscope includes a broadband light source configured to generate broadband optical signal(s). The broadband optical signal(s) propagate in an optical resonator and are coupled in and out of the optical resonator by optical couplers. A phase modulator applies phase modulation to the optical signal(s) based on a sawtooth modulation signal. The optical signal(s) repropagate in the optical resonator in a different direction. The optical signal(s) are then received and analyzed to determine parameter(s) of the phase modulator. One or more processors configure the phase modulator based on the determined parameter(s).

Abstract: A Pound-Drever-Hall (PDH) offset servo circuit is configured to compensate for offset error identified from a received signal in an optical gyroscope. The PDH offset servo circuit determines offset error information from a quadrature-demodulated counterpropagating signal in the optical gyroscope, and uses the offset error information to generate a compensated PDH error signal. The compensated PDH error signal can be used to adjust the setpoint of the PDH loop circuitry, thereby enabling the PDH loop circuitry to generate a control signal to a laser that controls the frequency output of the laser with reduced offset error.

Abstract: A gyroscope comprises a source emitting a broadband beam, and a first waveguide arrangement that splits the beam into CCW and CW beams. First and second phase modulators are coupled to the waveguide arrangement and provide phase modulations or frequency shifts to the CCW and CW beams. An optical resonator is in communication with the phase modulators such that the CCW and CW beams are optically coupled into the resonator. A second waveguide arrangement receives the CCW and CW beams transmitted from the resonator. First and second RIN detectors are coupled to the second waveguide arrangement and respectively receive the CCW and CW beams. A rate detector receives the CCW and CW beams. A rate calculation unit receives intensity noise signals from the RIN detectors, and rate and intensity noise signals from the rate detector. The rate calculation unit performs a RIN subtraction technique to reduce intensity noise limited ARW.

Abstract: A method for a resonant fiber optic gyroscope is provided. The method includes locking a frequency of a light wave from a master laser to a resonant frequency of a fiber optic resonator; phase locking a first slave laser to the frequency of the master laser at a first offset frequency; combining the light wave from the master laser with a light wave from the first slave laser; launching the combined light wave in the clockwise (CW) direction in the fiber optic resonator; and prior to combining the light wave from the master laser and the light wave from the first slave laser, shifting the frequency of the light wave from the master laser to avoid interference with a signal produced by pick-up in the first slave laser, that includes a light wave at the frequency of the light wave from the master laser.

Abstract: A photonics gyroscope comprises a light source on a photonics chip that emits a broadband beam; a waveguide resonator; a reflective component; first and second detectors, the second detector coupled to the source; a RIN servo loop coupled between the second detector and the source; and a rate calculation unit. The beam is directed into the resonator such that it propagates in a CCW direction. A portion of the CCW beam is coupled out of the resonator toward the reflective component and reflected back as a reflected beam that is coupled into the resonator such that the reflected beam propagates in a CW direction. The CW beam is coupled out of the resonator to the first detector, which detects a resonance frequency shift between the CW and CCW beams. The RIN servo loop stabilizes an intensity of the beam such that bias error and noise is reduced.

Abstract: In some embodiments, a system includes a laser that generates an optical signal and a resonator that receives the optical signal. The resonator includes an optical resonator cavity comprising a first and second end, wherein the optical signal propagates at a resonant frequency; a first optical anti-resonator terminating the first end and having a first stopband; and a second optical anti-resonator terminating the second end and having a second stopband. The system includes a detector that generates an electrical signal from a modified resonator output of the resonator; and Pound-Drever-Hall servo circuitry configured to generate control signals for controlling a frequency of the optical signal generated by the laser or phase modulation devices attached to the optical resonator cavity or the first or second optical anti-resonator, wherein each phase modulation changes a length of at least one of the optical resonator cavity or the first or second optical anti-resonator.

Abstract: Systems and methods for reducing rotation sensing errors from laser source signal and modulation cross-talk are provided herein. An RFOG includes a fiber optic resonator; a first laser source that produces a first light wave at a first carrier frequency and a first cross-talked portion at a second carrier frequency wave for propagating in a first direction, wherein a second cross-talked portion propagates in a second direction that is opposite to the first direction; a second laser source that produces a second light wave for propagating in the second direction at a second carrier frequency, and having a third cross-talked portion that propagates in the first direction, a first modulator that modulates the first light wave by suppressing light at the first carrier frequency and the second cross-talked portion at the second carrier frequency, and photodetectors that generate signals from the modulated first light wave and the second light wave.

Abstract: Systems and methods for reducing rotation sensing errors from laser source signal and modulation cross-talk are provided herein. An RFOG includes a fiber optic resonator; a first laser source that produces a first light wave at a first carrier frequency and a first cross-talked portion at a second carrier frequency wave for propagating in a first direction, wherein a second cross-talked portion propagates in a second direction that is opposite to the first direction; a second laser source that produces a second light wave for propagating in the second direction at a second carrier frequency, and having a third cross-talked portion that propagates in the first direction, a first modulator that modulates the first light wave by suppressing light at the first carrier frequency and the second cross-talked portion at the second carrier frequency, and photodetectors that generate signals from the modulated first light wave and the second light wave.

Abstract: Systems and methods for an injection locking RFOG are described herein. In certain embodiments, a system includes an optical resonator. The system also includes a laser source configured to launch a first laser for propagating within the optical resonator in a first direction and a second laser for propagating within the optical resonator in a second direction that is opposite to the first direction, wherein the first laser is emitted at a first launch frequency and the second laser is emitted at a second launch frequency. Moreover, the system includes at least one return path that injects a first optical feedback for the first laser and a second optical feedback for the second laser, from the optical resonator, into the laser source, wherein the first and second optical feedbacks respectively lock the first and second launch frequencies to first and second resonance frequencies of the optical resonator.

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: Systems and methods for an injection locking RFOG are described herein. In certain embodiments, a system includes an optical resonator. The system also includes a laser source configured to launch a first laser for propagating within the optical resonator in a first direction and a second laser for propagating within the optical resonator in a second direction that is opposite to the first direction, wherein the first laser is emitted at a first launch frequency and the second laser is emitted at a second launch frequency. Moreover, the system includes at least one return path that injects a first optical feedback for the first laser and a second optical feedback for the second laser, from the optical resonator, into the laser source, wherein the first and second optical feedbacks respectively lock the first and second launch frequencies to first and second resonance frequencies of the optical resonator.

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 resonant fiber optic gyroscope (RFOG) comprises two integrated photonics interfaces coupling the optical resonator coil to the multi-frequency laser source that drives the RFOG; wherein the two integrated photonics interfaces comprise a first waveguide layer and a second waveguide layer wherein the first waveguide layer comprises two waveguide branches which come together to form a single waveguide branch; the second waveguide layer comprises two waveguide branches which remain separate from each other; and wherein the waveguide structure is configured to match an integrated photonics mode to a fiber mode supported by an optical fiber.