An optical connection component includes: a plurality of types of optical fibers; a plurality of high relative refractive-index difference optical fibers in each of which a relative refractive-index difference between a core and a cladding is larger than a relative refractive-index difference in each of the plurality of types of optical fibers and which are fusion spliced to the plurality of types of optical fibers; and a fixing member having a plurality of V-shaped grooves that receive the high relative refractive-index difference optical fibers with coating removed, the fixing member being configured to fix relative positions of the high relative refractive-index difference optical fibers and an optical element when optically coupling the high relative refractive-index difference optical fibers, which have been fusion spliced to the plurality of types of optical fibers, to the optical element. The high relative refractive-index difference optical fibers are of the same type.

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.

The present invention relates to a programmable multicore photonic integrated circuit comprising at least one programmable photonic modules or cores, and/or other photonic units like specific high performance blocks, capable of implementing multipurpose signal processing, by the appropriate programming of its resources, routing within the circuits and the blocks to achieve multifunctional operation and the selection of its input and output ports. The invention also relates to a scalable programmable photonic integrated circuits arranged in a modular multicore approach to increase the processing power of the overall system and/or adding a multitude of functionalities enabled by complex photonics circuitry and parallelization as well as the related operation methods.

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of the optical fighter using a two-photon polymerization process on a photosensitive polymer by a three-dimensional micromachining device. The three-dimensional microscopic optical structure having a hinged optical layer pivotally connected to a distal portion of a suspended structure. A reflective layer is deposited on a mirror surface of the hinged optical layer while in an open position. The hinged optical layer is subsequently positioned in the closed position to align the mirror surface to at least partially reflect a light signal back through the optical fiber.

The present invention provides a temperature-insensitive Mach-Zehnder interferometer, including: a first mode converter; a second mode converter, located on one side of the first mode converter and with a distance from the first mode converter; and a connecting arm, located between the first mode converter and the second mode converter, one end of the connecting arm is connected with the first mode converter, and the other end is connected with the second mode converter. The connecting arm includes a straight waveguide connecting arm. The temperature-insensitive Mach-Zehnder interferometer of the present invention can be configured to be insensitive to temperature by adjusting parameters such as the width and thickness of the connecting arm.

A temporal multiplexing circuit can include a set of waveguides having different delay lengths, with the waveguides arranged according to a de Bruijn sequence. The set of waveguides can be coupled to a cyclic switch that selectably delivers a group of unsynchronized photons (or other signal pulses) from a contiguous group of input paths into a contiguous group of the delay waveguides. Similarly, a spatial multiplexing circuit can include a set of pairs of waveguides that each implement mode swapping of photons, with different swap distances, with the pairs of waveguides arranged according to a de Bruijn sequence. The set of waveguides can be coupled to a cyclic switch that selectably delivers a group of photons from a set of input paths into a contiguous group of the mode-swap waveguides. Temporal and spatial multiplexing can be combined in a switching network.

Structures for a coupler and methods of forming a structure for a coupler. A structure for a directional coupler may include a first waveguide core having one or more first airgaps and a second waveguide core including one or more second airgaps. The one or more second airgaps are positioned in the second waveguide core adjacent to the one or more first airgaps in the first waveguide core. A structure for an edge coupler is also provided in which the waveguide core of the edge coupler includes one or more airgaps.

Integrated passive/active modulator units, integrated passive/active modulators comprising one or more units, and corresponding methods of fabrication and use are provided. In an example embodiment, a unit comprises an upstream passive portion comprising a passive waveguide; a downstream passive portion comprising a continuation of the passive waveguide; and an active portion between the upstream passive portion and the downstream passive portion. The active portion comprises an active waveguide and electrical contacts in electrical communication with the active waveguide. The active waveguide comprises an upstream taper and/or a downstream taper. The upstream taper is configured to optically couple the active waveguide to the passive waveguide of the upstream portion and the downstream taper is configured to optically couple the active waveguide to the continuation of the passive waveguide of the downstream portion.

In some implementations, a Mach-Zehnder interferometer (MZI) includes a delay line arm formed in a chip and a mirrored facet formed in the chip. The delay line arm may be configured to propagate light to the mirrored facet. The mirrored facet may be configured to reflect, to the delay line arm, a percentage of the light propagated to the mirrored facet by the delay line arm.

Embodiments relate to an optical sensor for sensing hydrogen gas, which includes an optical fiber through which light moves; a ferrule formed at one end of the optical fiber to surround the optical fiber; and a sensor module configured to form an interference wave according to a Fabry-Perot interferometer with respect to light that moves through the optical fiber, wherein the sensor module includes a sensing material that expands and contracts by reacting with hydrogen gas, and spectrum periodicity of the interference wave changes according to a volume change of the sensing material, and a hydrogen gas detection system including the optical sensor.