An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, and a first access waveguide. The first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer. The second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer. The first loop waveguide is optically coupled to the first multiplexer/demultiplexer. The second loop waveguide is optically coupled to the second multiplexer/demultiplexer. The first waveguide is optically coupled to the first multiplexer/demultiplexer and the second multiplexer/demultiplexer. The first access waveguide is optically coupled to the first waveguide.

An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, a second waveguide optically coupled to the first loop mirror and the second loop mirror, a first access waveguide optically coupled to the first waveguide, a second access waveguide optically coupled to the second waveguide, and an output section, wherein the first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer, the second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer, the output section includes a third loop waveguide, a third multiplexer/demultiplexer, a third waveguide, and a fourth waveguide, the third loop waveguide optically coupled to the second loop waveguide and the third multiplexer/demultiplexer, the third waveguide and the fourth waveguide optically coupled to the third multiplexer/demultiplexer, and the output section.

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 fiber optic temperature sensor, a sensing head structure, and a manufacturing method are provided. The fiber optic temperature sensor includes a broad spectrum light source, a first fiber optic coupler, a spectrometer, a first sensing interferometer, and a second sensing interferometer. The first sensing interferometer and the second sensing interferometer have opposite temperature responses. A first free spectral range corresponding to the first sensing interferometer is close to but not equal to a second free spectral range corresponding to the second sensing interferometer. In the fiber optic temperature sensor, two sensing interferometers both sensitive to temperature are used, and the two sensing interferometers have opposite temperature responses, thereby achieving an enhanced vernier effect, and improving the sensitivity of temperature measurement.

An interferometric system with multi-axis optical fiber and a method for processing an interferometric signal in such a system, the multi-axis interferometric system includes a light source (1); a plurality of N optical-fiber coils (11, 12), a first optical separation element (3) capable of splitting the source beam (100) into a first split beam (140) and a second split beam (240); shared phase-modulation element (4); a photodetector (2) and a signal-processing system (800). The N optical-fiber coils (11, 12) are connected in parallel, the coils having respective transit times T1, T2, . . . TN that all differ from one another, and the signal-processing system (800) is capable of processing the interferometric signal (720) detected by the shared photodetector (2) as a function of the respective transit times in the various coils.

A ring-resonator filter device includes: a waveguide device that includes a core. Further, the core constitutes two ring resonator filters, each of the two ring resonator filters includes two arm portions, a ring-shaped portion, and two optical coupling/branching portions that optically couple the two arm portions and the ring-shaped portion, respectively, and the two ring-shaped portions cross each other.

A fiber optic temperature sensor, a sensing head structure, and a manufacturing method are provided. The fiber optic temperature sensor includes a broad spectrum light source, a first fiber optic coupler, a spectrometer, a first sensing interferometer, and a second sensing interferometer. The first sensing interferometer and the second sensing interferometer have opposite temperature responses. A first free spectral range corresponding to the first sensing interferometer is close to but not equal to a second free spectral range corresponding to the second sensing interferometer. In the fiber optic temperature sensor, two sensing interferometers both sensitive to temperature are used, and the two sensing interferometers have opposite temperature responses, thereby achieving an enhanced vernier effect, and improving the sensitivity of temperature measurement.

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.

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.

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.