An improved-type of interferometric fiber-optic gyroscope (FOG) is proposed, which is used for the observation and measurement of the Sagnac effect to determine the angular speed of a rotational movement with enhanced measurement sensitivity and accuracy. The improved FOG is characterized by the combined use of a polarization-maintaining mechanism, a symmetric beam-splitting configuration for the 3×3 directional coupler, a common optical path for the opposing beams, and a pair of photo detectors for the detection of a pair of differential phase signals that indicate the angular speed of the rotational movement. The combined use of these approaches can help significantly eliminate and reduce the common mode phase noises caused by polarization crosstalk to a minimum possible level that has never been achieved by the conventional FOGs, thus significantly enhancing the measurement sensitivity and accuracy to a much higher level.

A photonic integrated circuit (PIC) comprises at least two optical circuits disposed on the PIC, two or more optical interfaces each configured to provide a connection to at least one external optical component, and a layout arrangement of the at least two optical circuits on the PIC, the layout arrangement configured such that the two or more optical interfaces are situated in at least one local group of optical interfaces, and the at least one local group of optical interfaces is located on at least one facet of the PIC. The at least two optical circuits may comprise a set of N single-axis 2×2 optical fiber optic gyroscope (FOG) circuits for use as a multi-axis FOG assembly in an inertial management unit (IMU) or an inertial navigation system (INS).

Disclosed is a chip-level resonant acousto-optic coupling solid-state wave gyroscope based on MEMS technology. A surface acoustic progressive wave mode sensitive structure and a micro-ring resonant cavity optical detection structure are combined in the gyroscope. Through acousto-optic effect, mechanical strain of the device crystal caused by wave vibration of a primary surface acoustic wave and a secondary surface acoustic wave caused by Coriolis force is converted into a variation in the refractive index of an optical waveguide etched on the device, so that the optical signal transmitted in the waveguide diffracts, thereby generating frequency modulation. Meanwhile, a micro-ring resonant cavity using the resonance principle peels off the frequency change introduced by the primary surface acoustic wave, and obtains an output signal containing external angular velocity information. Based on the proportional relationship between the detection resolution and the quality factor of the micro-ring resonant cavity, the order of magnitude of the interface detection resolution is improved, and the performance indicators of the gyroscope are simultaneously optimized in terms of improving sensitivity and resolution, and its precision is improved.

A silicon photonic integrated circuit is provided, which includes a first optical power splitter, a second optical power splitter, a first grating coupler and a second grating coupler. The first optical power splitter has an input, a first output and a second output, in which the input is configured to receive an inputted beam, and the first output is configured to output a returned beam. The second optical power splitter has an input, a first output and a second output, in which the input is coupled to the second output of the first optical power splitter. The first and second grating couplers are respectively coupled to the first and second outputs of the second optical power splitter, and are configured to optically couple two opposite ends of a fiber coil, respectively.

A system for stabilizing a scale factor associated with an optic rotation sensor comprises an optic rotation sensor that generates an optic signal in response to a rotation of the optic rotation sensor. A sensor detection system produces a rotation signal as a function of the optic signal and rotation of the optic rotation sensor. A first waveguide guides a portion of the optic signal for an interaction length, and produces a first processed optic signal. A second waveguide receives a portion of the optic signal from first waveguide through evanescent coupling, and produces a second processed optic signal. A wavemeter detector receives the optic signals and measures the effective interferometric wavelength (EIW) of the light based on the optic signals. A scale factor correction system receives the rotation signal and the EIW, and measures the correct rotation signal by processing the rotation signal and the EIW.

An improved fiber-optic gyroscope (FOG) is proposed for enhancing the optical measurement sensitivity through the application of a heterodyne effect. The improved FOG is characterized by the use of a dual-injection polarization-maintaining 3×3 directional coupler which is configured to receive a pair of source light beams that are injected thereinto in a bi-directional manner. The forward-injected light beam is used to be split into a pair of interrogating beams for use by a coiled optical fiber to implement the detection and measurement of the Sagnac effect due to a rotational movement. On the other hand, the backward-injected light beam is used to be mixed with the paired interrogating beams that have passed through and returned from the coiled optical fiber to thereby provide a heterodyne effect that can boost the differential optical power amplitude of the paired interrogating beams, thereby enhancing the optical measurement sensitivity of the FOG application.

A silicon photonic integrated circuit is provided, which includes a first optical power splitter, a second optical power splitter, a first grating coupler and a second grating coupler. The first optical power splitter has an input, a first output and a second output, in which the input is configured to receive an inputted beam, and the first output is configured to output a returned beam. The second optical power splitter has an input, a first output and a second output, in which the input is coupled to the second output of the first optical power splitter. The first and second grating couplers are respectively coupled to the first and second outputs of the second optical power splitter, and are configured to optically couple two opposite ends of a fiber coil, respectively.

A light amplitude balancing system for use in a photonic integrated circuit (PIC)-based fiber optic gyroscope (FOG) may comprise one or more 2×2 PIC-based FOG optical circuits and a PIC-based modulator assembly. The modulator assembly may be configured to receive one or more input light signals, and to produce one or more output light signals that (i) correspond to the input light signals and (ii) are conveyed to the one or more FOG optical circuits. Each of the one or more output light signals may have an amplitude that is a modified version of an amplitude of the corresponding input signal. The one or more FOG optical circuits and the PIC-based modulator assembly may be disposed on a common PIC substrate. Alternatively, the one or more FOG optical circuits may be disposed on a first PIC substrate, and the PIC-based modulator assembly may be disposed on a second PIC substrate.

An optical gyroscope assembly for measuring a rotation rate. The optical gyroscope assembly includes a first multimode interferometer with an input for receiving light and two outputs, each connected to a second light guide; a ring resonator on each of the second light guides; a second multimode interferometer with two inputs, each connected to one of the second light guides, and two outputs, each connected to a third light guide; and a third multimode interferometer with two inputs, each connected to one of the third light guides, and two outputs, each connected to a fourth light guide.

Disclosed is a chip-level resonant acousto-optic coupling solid-state wave gyroscope based on MEMS technology. A surface acoustic progressive wave mode sensitive structure and a micro-ring resonant cavity optical detection structure are combined in the gyroscope. Through acousto-optic effect, mechanical strain of the device crystal caused by wave vibration of a primary surface acoustic wave and a secondary surface acoustic wave caused by Coriolis force is converted into a variation in the refractive index of an optical waveguide etched on the device, so that the optical signal transmitted in the waveguide diffracts, thereby generating frequency modulation. Meanwhile, a micro-ring resonant cavity using the resonance principle peels off the frequency change introduced by the primary surface acoustic wave, and obtains an output signal containing external angular velocity information. Based on the proportional relationship between the detection resolution and the quality factor of the micro-ring resonant cavity, the order of magnitude of the interface detection resolution is improved, and the performance indicators of the gyroscope are simultaneously optimized in terms of improving sensitivity and resolution, and its precision is improved.