Photonic devices are disclosed including a first cladding layer, a first electrical contact comprising a first lead coupled to a first dielectric portion, a second electrical contact comprising a second lead coupled to a second dielectric portion, a waveguide structure comprising a slab layer comprising a first material, and a second cladding layer. The slab layer may be coupled to the first dielectric portion of the first electrical contact and the second dielectric portion of the second electrical contact. The first dielectric portion and the second dielectric portion may have a dielectric constant greater than a dielectric constant of the first material.

An optical element including a plurality of first circuits, the optical element includes a first cascade circuit in which one or more of first circuits are connected in cascade, a second cascade circuit in which one or more of first circuits are connected in cascade, and a combiner circuit configured to connect the first cascade circuit and the second cascade circuit. A first circuit included in the plurality of first circuits includes a first cascade structure in which N (N is an integer of 1 or larger) of 2-input and 2-output phase shifters and (N+1) of 2-input and 2-output couplers are alternately connected in cascade, and a first controller configured to control the N phase shifters in a direction in which optical input power decreases, the first controller being connected to one of two outputs of the first cascade structure.

A photonic integrated circuit includes a slot optical waveguide having an optical core with sub-wavelength slot therein that is partially filled with a first lower-index material having a negative thermo-optic coefficient. The slot may also include a second lower-index material having a positive thermo-optic coefficient. The relative volume of the first lower-index material within the slot may be configured to provide athermal or nearly-athermal operation. Example applications include integrated AWG MUX/DEMUX devices, Mach-Zehnder modulators, and micro-ring resonators or modulators implemented with silicon-based or silicon-nitride based slot waveguides with reduced sensitivity to temperature changes.

The disclosed technology can be implemented in photonics integrated circuit (PIC) to provide an optical frequency detection device for measuring an optical frequency of light using two Mach-Zehnder interferometer where the delay imbalance in the first interferometer is configured to be one quarter wavelength longer than that of the second interferometer to produce an additional phase difference between the two arms. The two outputs of each interferometer are then detected by two photodetectors to produce two complementary interference signals. The difference between the two complementary interference signals of the first interferometer is a sine function of the optical frequency while the difference between the two complementary interference signals of the second interferometer is proportional to a cosine function of the optical frequency. Using the sine/cosine interpretation algorithm commonly used for the rotation encoders/decoders, any increments in optical frequency can be readily obtained.

An optical device includes: a substrate; an optical waveguide that forms a Mach-Zehnder interferometer; a signal electrode; and a ground electrode. The optical waveguide is placed between the signal electrode and the ground electrode. An electric field is generated in a direction along a surface of the substrate when a voltage is applied between the signal electrode and the ground electrode. The optical waveguide includes a first waveguide through which input light propagates, a curved waveguide which is optically coupled to the first waveguide, and a second waveguide which is optically coupled to the curved waveguide. The signal electrode includes first and second electrodes that are respectively placed near the first and second waveguides. An electric signal is supplied to the first electrode, and an inverted electric signal is supplied to the second electrode.

An optical system may include a scanning element, a detector, and a planar lightwave circuit (PLC)-based walk-off compensator. The PLC-based walk-off compensator may include a plurality of input waveguides associated with receiving an optical signal from the scanning element. The PLC-based walk-off compensator may include an optical switch configured to select one or more input waveguides, from the plurality of input waveguides, to be coupled to the detector. The selection of the one or more input waveguides may be based on an expected walk-off of the optical signal. The PLC-based walk-off compensator may include an output waveguide to provide the optical signal to the detector.

The disclosed technology can be implemented in photonics integrated circuit (PIC) to provide an optical frequency detection device for measuring an optical frequency of light using two Mach-Zehnder interferometer where the delay imbalance in the first interferometer is configured to be one quarter wavelength longer than that of the second interferometer to produce an additional phase difference between the two arms. The two outputs of each interferometer are then detected by two photodetectors to produce two complementary interference signals. The difference between the two complementary interference signals of the first interferometer is a sine function of the optical frequency while the difference between the two complementary interference signals of the second interferometer is proportional to a cosine function of the optical frequency. Using the sine/cosine interpretation algorithm commonly used for the rotation encoders/decoders, any increments in optical frequency can be readily obtained.

Silicon photonics provides an attractive platform for optoelectronic integrated circuits (OEICs) exploiting hybrid or monolithic integration with or without concurrent integration of microelectromechanical systems (MEMS) and/or CMOS electronic. Such OEICs offering optical component solutions across multiple applications from optical sensors through to optical networks operating upon one or more wavelengths. Accordingly, various silicon photonic building blocks are required in order to provide a toolkit for a circuit designer to exploit OEICs where these building blocks must address specific aspects of OEICs such as polarisation dependency of the optical waveguides. Accordingly, the inventors have established designs for: polarisation rotators with MEMS based tuning to allow the dual polarisations from a polarisation splitter to be managed by an OEIC operating upon a single polarisation; analog or digital phase shifts with MEMS actuation for switches, attenuators etc.; and passband filters with MEMS tuning.

In the adjustment method of optical coupling for an optical integrated circuit according to the present disclosure, the optimal adjustment position of optical coupling is determined on the basis of, for example, a sum of a plurality of photocurrents at electrodes on arm waveguides respectively formed on the plurality of MZIs in the polarization-multiplexing IQ modulator. According to the maximum value of the sum of the plurality of photocurrents, the light condensing spot position is adjusted to the center position of the end face core of the optical waveguide of the integrated chip. Typically, the light condensing spot position is adjusted to the center of the end face core by displacing the two input lenses.

An interferometer comprises a plurality of waveguide branches comprising a plurality of bus waveguides and a plurality of photonic resonators. A first waveguide branch of the plurality of waveguide branches comprises a first photonic resonator coupled to a first bus waveguide. The first photonic resonator is disposed to couple and circle a first portion of an optical beam at the first photonic resonator to generate a first phase shift of the first portion of the optical beam, where the first phase shift is the same as a second phase shift of a second photonic resonator coupled to a second bus waveguide.