An optical functional device includes a package case accommodating an optical functional element, an input optical fiber, and an output optical fiber. The optical functional device includes a first reflecting surface that reflects input light output from the input optical fiber to an optical path of output light, a second reflecting surface that reflects the input light to the optical functional element, and a third reflecting surface that reflects the output light in a direction in which the output light becomes further away from an optical axis of the input optical fiber. An optical axis of a leaked light beam transmitted through the second reflecting surface after being reflected by the first reflecting surface or an extension line of the optical axis in an optical propagation medium does not include a portion that is aligned with an optical axis of the output light reflected by the third reflecting surface.

An optical modulator includes an optical modulation element having a plurality of signal electrodes, a plurality of signal input terminals, a relay substrate on which a plurality of signal conductor patterns that electrically connect the signal input terminals and the signal electrodes and a plurality of ground conductor patterns are formed, and a housing. A signal input side and signal output side of the relay substrate face each other in a plan view, and electromagnetic wave propagation suppressing units that are made of a material that absorbs electromagnetic waves and have a height protruding from a surface of the relay substrate are provided, along at least one side of an end portion of the signal input side and an end portion of the signal output side in the plan view.

In an optical waveguide device using a convex optical waveguide, the absorption loss of guided light at an intersection between an optical waveguide and an electrode is reduced, without deteriorating optical characteristics and reducing long-term reliability. Provided is an optical waveguide device including a substrate on which an optical waveguide is formed, and an electrode having an intersection crossing over the optical waveguide on the substrate, in which the optical waveguide is formed with a protruding portion extending on the substrate, a resin layer is provided between the optical waveguide and the electrode at the intersection, the resin layer is formed to cover an upper surface and a side surface of the protruding portion of the optical waveguide, and in a cross section along a width direction of the optical waveguide, a boundary with the electrode is formed with a curve.

Techniques for the integration of SiGe/Si optical resonators with qubit and CMOS devices using structured substrates are provided. In one aspect, a waveguide structure includes: a wafer; and a waveguide disposed on the wafer, the waveguide having a SiGe core surrounded by Si, wherein the wafer has a lower refractive index than the Si (e.g., sapphire, diamond, SiC, and/or GaN). A computing device and a method for quantum computing are also provided.

A graphene structure includes one or more graphene layers. The graphene layers allow for microwave squeezing with gains up to 24 dB over a wide bandwidth.

An optical device is described. The optical device includes a waveguide, a first engineered electrode, and a second engineered electrode. The waveguide includes at optical material(s) having an electro-optic effect. The optical material(s) include lithium. A portion of the waveguide has a waveguide width. The first engineered electrode includes a first channel region and first extensions protruding from the first channel region. The first extensions are closer to the portion of the waveguide than the first channel region is. The second engineered electrode includes a second channel region and second extensions protruding from the second channel region. The second extensions are closer to the portion of the waveguide than the second channel region is. A first extension of the first extensions is a distance from a second extension of the second \extensions. The distance is less than the waveguide width.

An optical device includes: a ground electrode having a ground potential; a thin film optical waveguide formed by a thin film substrate stacked on the ground electrode; a signal electrode that is arranged at a position facing the ground electrode across the thin film optical waveguide and that transmits a high frequency signal; and a dielectric that covers at least a part of an exposed surface of the signal electrode.

To provide a highly-reliable low-cost small optical modulator in which temperature drift is suppressed and an optical transmission device using the same. An optical modulator including an optical waveguide substrate 1 on which an optical waveguide is formed, a signal electrode which is provided on the optical waveguide substrate and applies an electric field to the optical waveguide, a termination substrate 3 provided with a termination resistor that terminates the signal electrode, and a housing 6 in which the optical waveguide substrate and the termination substrate are mounted, in which, in order to suppress conduction of heat generated from the termination resistor to the optical waveguide substrate through the housing, a groove 8 is formed in the housing 6 between the termination substrate 3 and the optical waveguide substrate 1.

An optical device includes an optical waveguide formed of a crystal thin film having an electro-optic effect, an RF electrode configured to apply a high-frequency voltage to the optical waveguide, and a DC electrode configured to apply a DC voltage to the optical waveguide, wherein the RF electrode has a coplanar electrode configuration, and the DC electrode has a microstrip electrode configuration.

A composite substrate for an electro-optic element is disclosed. The composite substrate includes: an electro-optic crystal substrate having an electro-optic effect; a low-refractive-index layer being in contact with the electro-optic crystal substrate and having a lower refractive index than the electro-optical crystal substrate; and a support substrate bonded to the low-refractive-index layer at least via a bonding layer. A plurality of interfaces located between the low-refractive-index layer and the support substrate includes at least one rough interface having a roughness that is larger than a roughness of an interface between the electro-optic crystal substrate and the low-refractive-index layer.