The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

Provided is an optical waveguide with an inscribed Bragg grating, where the Bragg grating is stable at high temperature, has low scattering loss and high reflectivity. Also provided is a method for inscribing a Bragg grating in an optical waveguide, the method comprising irradiating the optical waveguide with electromagnetic radiation from an ultrashort pulse duration laser of sufficient intensity to cause a permanent change in an index of refraction within a core of the optical waveguide, where the irradiating step is terminated prior to erasure of a Bragg resonance, and heating the optical waveguide to a temperature and for a duration sufficient to substantially remove a non-permanent grating formed in the optical waveguide by the irradiating step.

Provided is an optical waveguide with an inscribed Bragg grating, where the Bragg grating is stable at high temperature, has low scattering loss and high reflectivity. Also provided is a method for inscribing a Bragg grating in an optical waveguide, the method comprising irradiating the optical waveguide with electromagnetic radiation from an ultrashort pulse duration laser of sufficient intensity to cause a permanent change in an index of refraction within a core of the optical waveguide, where the irradiating step is terminated prior to erasure of a Bragg resonance, and heating the optical waveguide to a temperature and for a duration sufficient to substantially remove a non-permanent grating formed in the optical waveguide by the irradiating step.

An integrated wavelength-selective filter device comprises a first optical element, for directing received radiation into a direction defined by a first angle, and a second optical element being a diffractive element configured for diffracting the directed radiation under a second angle. The second angle is such that for a single reference wavelength the diffracted radiation is directed into a propagation medium for advancing therein towards a predetermined position on the first optical element or on a further optical element for filtering radiation having a wavelength substantially matching the reference wavelength from radiation having a substantially different wavelength. The propagation medium is formed from a material that is different from any material of the substrate of the first and the second optical element.

An integrated wavelength-selective filter device comprises a first optical element, for directing received radiation into a direction defined by a first angle, and a second optical element being a diffractive element configured for diffracting the directed radiation under a second angle. The second angle is such that for a single reference wavelength the diffracted radiation is directed into a propagation medium for advancing therein towards a predetermined position on the first optical element or on a further optical element for filtering radiation having a wavelength substantially matching the reference wavelength from radiation having a substantially different wavelength. The propagation medium is formed from a material that is different from any material of the substrate of the first and the second optical element.

An integrated mode converter and multiplexer (/demultiplexer) is disclosed, which combines a multimode interference coupler (100), at least one phase-shifter (200) and a symmetrical Y-junction (300). The dispersion of the multimode interference coupler (100) is engineered through subwavelength structures in order to achieve a very wide bandwidth. Several phase-shifter (200) topologies for further bandwidth enhancement are disclosed, as well as architectures for multiplexing a greater number of optical modes.

An integrated mode converter and multiplexer (/demultiplexer) is disclosed, which combines a multimode interference coupler (100), at least one phase-shifter (200) and a symmetrical Y-junction (300). The dispersion of the multimode interference coupler (100) is engineered through subwavelength structures in order to achieve a very wide bandwidth. Several phase-shifter (200) topologies for further bandwidth enhancement are disclosed, as well as architectures for multiplexing a greater number of optical modes.

A system includes: an objective lens; a first light source to feed first illuminating light through the objective lens and into a flowcell (e.g., with a relatively thin film waveguide) to be installed in the system, the first illuminating light to be fed using a first grating on the flowcell; and a first image sensor to capture imaging light using the objective lens, wherein the first grating is positioned outside a field of view of the first image sensor. Dual-surface imaging can be performed. Flowcells with multiple swaths bounded by gratings can be used. An auto-alignment process can be performed.

Included are a transmitter and a receiver caused to have a constant temperature. The transmitter includes: a semiconductor optical amplifier having a reflection mirror at a first end thereof; an optical waveguide having a first end coupled to a second end of the semiconductor optical amplifier; a wavelength demultiplexing filter having an input port coupled to a second end of the optical waveguide and a plurality of output ports having constant transmission wavelength intervals; reflection structures to reflect part of light output from the output ports, the reflection structures provided for the respective output ports of the wavelength demultiplexing filter; modulators to modulate light transmitted through the reflection structures, the modulators provided for the respective reflection structures; and a wavelength multiplexing filter having input ports coupled to the respective output ends of the modulators, transmission wavelength intervals of the input ports being identical to the transmission wavelength intervals of the wavelength demultiplexing filter, and having the output port coupled to a first end of an optical fiber. The receiver includes: a wavelength demultiplexing filter having an input port coupled to a second end of the optical fiber and a plurality of output ports having the same transmission wavelength intervals as the transmission wavelength intervals of the wavelength demultiplexing filter and an FSR obtained by multiplying the transmission wavelength interval by the number of the output ports; light receivers to receive light output from the output ports, the light receivers provided for the respective output ports of the wavelength demultiplexing filter; and a temperature controller to control the temperature of the wavelength demultiplexing filter.

Included are a transmitter and a receiver caused to have a constant temperature. The transmitter includes: a semiconductor optical amplifier having a reflection mirror at a first end thereof; an optical waveguide having a first end coupled to a second end of the semiconductor optical amplifier; a wavelength demultiplexing filter having an input port coupled to a second end of the optical waveguide and a plurality of output ports having constant transmission wavelength intervals; reflection structures to reflect part of light output from the output ports, the reflection structures provided for the respective output ports of the wavelength demultiplexing filter; modulators to modulate light transmitted through the reflection structures, the modulators provided for the respective reflection structures; and a wavelength multiplexing filter having input ports coupled to the respective output ends of the modulators, transmission wavelength intervals of the input ports being identical to the transmission wavelength intervals of the wavelength demultiplexing filter, and having the output port coupled to a first end of an optical fiber. The receiver includes: a wavelength demultiplexing filter having an input port coupled to a second end of the optical fiber and a plurality of output ports having the same transmission wavelength intervals as the transmission wavelength intervals of the wavelength demultiplexing filter and an FSR obtained by multiplying the transmission wavelength interval by the number of the output ports; light receivers to receive light output from the output ports, the light receivers provided for the respective output ports of the wavelength demultiplexing filter; and a temperature controller to control the temperature of the wavelength demultiplexing filter.