A method for operating a fiber optic gyroscope to measure angular velocity uses a closed-loop modulation scheme. Two-state modulation voltages are applied to an optical modulator and continuously adjusted to maintain a null difference between corresponding demodulated voltages from a photodetector. If one of the modulation voltages reaches a threshold voltage, the continuous nulling adjustment is interrupted briefly while the two-state modulation voltages are reset to values that correspond to relative phases of /2 and /2 when the gyroscope is stationary, then the continuous adjustment is resumed. This reoccurring resetting, while the gyroscope accelerates or decelerates, substantially increases the dynamic range over which the gyroscope can precisely measure angular velocity.

A method comprises receiving a first optical signal and a second optical signal at or near an optical resonator, where the first optical signal includes a clockwise (CW) optical signal and the second optical signal includes a counter clockwise optical signal; injecting the first optical signal and the second optical signal into a resonator loop closure optics system of the optical resonator; sampling a portion of the first optical signal and a portion of the second optical signal; combining the portion of the first optical signal and the second optical signal; converting the combined optical signals to an analog electrical signal; digitizing the analog electrical signal; storing an estimated frequency of a beat signal created by a combination of the CW optical signal and the CCW optical signal; and using the stored estimated beat signal frequency, digitally phase lock to a frequency of the beat signal.

A gyroscope of the present invention includes a moving standing light wave generator to generate three moving standing light waves, an atomic beam source to continuously generate an atomic beam in which individual atoms are in the same state, an interference device that exerts a Sagnac effect through interaction between the atomic beam and the three moving standing light waves, and a monitor to detect angular velocity or acceleration by monitoring an atomic beam from the interference device. Each moving standing light wave satisfies an n-th order Bragg condition, where n is a positive integer of 2 or more.

A system includes a modulation controller that generates a modulation output signal that is employed to generate a modulation output signal to control light signals in a fiber optic coil. The modulation controller receives light signal feedback from the fiberoptic coil and controls the light signals in the fiber optic coil with the modulation output signal based on the light signal feedback. A transit time clock in the modulation controller has a clock speed to control a time period of the modulation output signal generated by the modulation controller. The time period is set to a period less than an optical transit time, tau, of the light signals applied to the fiber optic coil and returned from the coil after being applied.

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.

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.

The present disclosure relates to system-level integration of lasers, electronics, integrated photonics-based optical components and a sensing chip. Novel waveguide design on the integrated photonics chip, acting as a front-end chip, ensures precise detection of phase change in a fiber coil or a sensing chip having a waveguide coil or ring resonator, where the sending chip is coupled to the front end chip. Strip waveguides are designed to primarily select TE mode over TM mode when laser light is coupled into the integrated photonics chip. A plurality of mode-selective filters, based on multi-mode interference (MMI) filter, a serpentine structure, or other types of waveguide-based mode-selective structure, are introduced in the system architecture. Additionally, implant regions are introduced around the waveguides and other optical components to block unwanted/stray light into the waveguides and optical signal leaking out of the waveguide.

A weak value amplification (WVA) Corolis vibratory gyroscope (CVG) is provided for measuring angular rate. The WVA CVG includes a vibratory structure that induces a deflection; an optical weak value amplifier that amplifies the deflection as an amplified signal; and a weak value detector to measure the amplified signal to determine the angular rate. Further exemplary embodiments provide first and second plates, a laser, a polarizing filter, a beam-splitter, left and right mirrors, a half-wave plate, a retarder and a detector. The first plate has four corners. The second plate has a flat surface that contacts one corner of the first plate at 45. The laser emits an emission beam of photons. The polarizing filter polarizes the emission beam. The beam-splitter divides the beam into left and right beams. The left and right mirrors reflect respective the left and right beams. The half-wave plate shifts polarization of the left and right beams by 90. The retarder imposes a phase difference between the left and right beams. The detector measures the left and right beams. The second plate vibrationally translates back and forth normal to the flat surface. The left and right beams reflect from the respective right and left mirrors, passing through the beam-splitter and reaching the detector.

A broadband light source apparatus, and corresponding method, includes a broadband light source configured to provide source light with a source wavelength spectrum having a centroid thermal sensitivity. The apparatus also includes a broadband optical filter characterized by a filter spectrum that has one or more spectral characteristics and a thermal sensitivity with magnitude and sign. The filter is configured to receive the source light and to deliver broadband output light with an output spectrum that is a function of the source and filter spectra and has an output centroid wavelength. The spectral characteristics and the magnitude and sign of the thermal sensitivity of the filter are configured to minimize a thermal sensitivity of the output centroid wavelength. The filter can be configured in view of a particular source spectrum to stabilize output centroid wavelength and maximize total output power passively with respect to ambient temperature fluctuations.

An embodiment of a gyroscope subsystem that is configured to reduce, or to eliminate, the effect of bias includes a gyroscope assembly, a calibration assembly, a determining circuit, and a bias-reducing circuit. The gyroscope assembly is configured to generate a gyroscope signal in response to a calibration angular velocity and another angular velocity about a sense axis, and the calibration assembly is configured to generate, about the sense axis, the calibration angular velocity. The determining circuit is configured to determine the other angular velocity in response to the gyroscope signal, and the bias-reducing circuit is configured to reduce a bias component of the determined other angular velocity in response to the gyroscope signal. For example, such a gyroscope subsystem can yield a value of an angular velocity having a bias component that is significantly less than the bias component of a value yielded by a conventional gyroscope subsystem.