Methods and apparatus for tuning a photonics-based component. An opto-electrical detector is configured to output an electrical signal based on a measurement of light intensity of the photonics-based component, the light intensity being proportional to an amount of detuning of the photonics-based component. Analog-to-digital conversion (ADC) circuitry is configured to output a digital signal based on the electrical signal output from the opto-electrical detector. Feedback control circuitry is configured to tune the photonics-based component based, at least in part, on the digital signal output from the ADC circuitry.

Methods and apparatus for tuning a photonics-based component. An opto-electrical detector is configured to output an electrical signal based on a measurement of light intensity of the photonics-based component, the light intensity being proportional to an amount of detuning of the photonics-based component. Analog-to-digital conversion (ADC) circuitry is configured to output a digital signal based on the electrical signal output from the opto-electrical detector. Feedback control circuitry is configured to tune the photonics-based component based, at least in part, on the digital signal output from the ADC circuitry.

A system and method for demodulation of a fiber optic interferometric sensor are provided. Another aspect pertains to a system and method employing a single laser to generate multiple quadratic wavelengths to demodulate fiber optic interferometric sensors with approximately sinusoidal fringes. Yet another aspect of the present system and method uses a single frequency laser which is split into multiple paths using a fiber optic coupler, with one path including an intensity modulator and another path including an acousto-optic modulator, whereafter the paths are recombined into a fiber which leads to an interferometric sensor, and the light reflected from the sensor is then directed to a photodetector. A further aspect employs a single frequency laser which is split into multiple paths, with the light in the paths being modulated at different frequencies, whereafter the paths are recombined into a fiber which leads to an interferometric sensor.

To provide an optical element that can be more easily aligned with an optical fiber, an optical element includes one grating coupler optically coupled to an optical fiber, a waveguide connected to the grating coupler, a multimode interferometer connected to the waveguide on the opposite side to the grating coupler, and a waveguide inserted between two input/output ports on the branched side of the multimode interferometer.

An electromagnetic radiation beam is inputted into a ring interferometer rotating at the angular velocity Ω where the beam is split into two equally intensive counter—propagating electromagnetic beams. The Sagnac Effect results in the phase shift of ±Pi/2 radians, which may be either positive or negative depending on the direction in which the counter-propagating electromagnetic radiation beams propagate with regard to the rotation direction of the ring interferometer. An additionally phase shift of Pi/2 radians is induced between the counter-propagating electromagnetic radiation beams inside the ring interferometer results in a total phase shift of either Pi radians or 0. The counter-propagating electromagnetic radiation beams inside the ring interferometer are then combined into one single electromagnetic radiation (EMR) beam which outputted from the rotating ring interferometer by using a different path than the one through which the EMR beam is inputted into it.

An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first portion with silicon nitride (SiN) waveguides that constitute a rotation sensing element; and, a second portion with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two portions can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform.

An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first portion with silicon nitride (SiN) waveguides that constitute a rotation sensing element; and, a second portion with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two portions can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform.

Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05/Hr or below (e.g. as low as 0.02/Hr), which makes them comparable to fiber optic gyroscopes (FOGs) in terms of performance, at a much lower cost. The low bias stability value in the integrated photonics optical gyroscope corresponds to a low bias estimation error (in the range of 1.5/Hr or even lower) that is crucial for safety-critical applications, such as calculating heading for autonomous vehicles, drones, aircrafts etc. The integrated photonics optical gyroscopes may be co-packaged with mechanical gyroscopes into a hybrid inertial measurement unit (IMU) to provide high-precision angular measurement for one or more axes.

An optical gyroscope and a method for measuring an angular velocity of rotation are described. A closed-path optical cavity is configured for receiving at least a first optical signal circulating as at least one cavity mode of pre-determined orientation (inside the optical cavity. An extractor in optical communication with the optical cavity is configured for extracting a fraction of at least the circulating first optical signal from the optical cavity, wherein an amplitude of the extracted fraction increases when a resonance condition for the optical cavity in optical communication with the extractor is approached. A readout channel included in the optical gyroscope comprises an interferometric device adapted to spectrally modify the extracted fraction so as to produce a spectral Vernier effect. A difference between free spectral ranges of the interferometric device and the optical cavity is larger than the associated spectral widths. Readout detectors are included in the readout channel for detecting optical power levels of the spectrally modified optical signal, based on which the angular velocity is determined.

Structures for a wavelength-division multiplexing filter and methods of fabricating a structure for a wavelength-division multiplexing filter. The structure includes a first waveguide core, a second waveguide core laterally spaced from the first waveguide core, and a ring resonator arranged in a vertical direction over the first waveguide core and the second waveguide core. The ring resonator is also arranged in a lateral direction between the first waveguide core and the second waveguide core. The first and second waveguide cores are composed of a semiconductor material, such as single-crystal silicon, and the ring resonator is composed of a dielectric material, such as silicon nitride.