Abstract: A silicon nitride core is formed on a silicon core via a first silicon oxide layer, and a germanium pattern caused to selectively grow in an opening penetrating through a second silicon oxide layer formed on the silicon nitride core and the first silicon oxide layer is formed on a lower silicon pattern formed to be continuous with the silicon core, thereby constituting a Ge photodiode.

Abstract: A core, constituted by an amorphous undoped semiconductor (i type), which is formed on a lower clad layer, and a p-type layer and an n-type layer which are disposed on the lower clad layer with the core interposed therebetween and are formed in contact with the core are provided. The core is formed to be thicker than the p-type layer and the n-type layer. The p-type layer and the n-type layer are constituted by single crystal silicon.

Abstract: An optical waveguide includes a cladding layer, a Si layer, a REO layer, and a cap layer. The REO layer is made of a single-crystal rare earth oxide, and is formed on the Si layer. The cap layer is formed on the REO layer. The cap layer may be made of a material transparent to light to be guided. The cap layer has a stripe shape extending in a direction in which light is guided.

Abstract: An optical nonlinearity measurement method according to the present disclosure utilizes photon pair generation through a spontaneous four-wave mixing process, to observe photon pairs using an optical waveguide loaded with a two-dimensional material. Compared with the Z-scan method, the influence of free carriers on nonlinear refractive indexes is only indirect. With a parameter being the length of the attached two-dimensional material in the optical waveguide direction, a theoretical value of the coincidence rate of the photon pairs based on the coupled wave equation is fitted to a measured value of the coincidence rate of the photon pairs. For the coincidence rate of the photon pairs, the theoretical value based on the coupled wave equation is fitted to the measured value in a state reflecting the structure of the optical waveguide loaded with the two-dimensional material, and nonlinear coefficients ?1 and ?2 at that time are obtained.

Abstract: An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E12 mode, for example.

Abstract: An oscillation unit (101), a measurement unit (102), and a bit generation unit (103) are included. The measurement unit (102) chronologically measures oscillation (for example, thermal oscillation) of a set frequency generated in the oscillation unit (101) at each set time. The bit generation unit (103) generates a bit string by allocating one bit of 0 or 1 to each of sine and cosine components of the oscillation measured by the measurement unit (102).

Abstract: A semiconductor optical device includes a light emitting layer that emits light in a state of current injection; an optical waveguide in which a width or a thickness in an extending direction (y) of the light emitting layer varies along the extending direction; and a uniform diffraction grating having constant cycle, width and depth, wherein the light emitting layer, the optical waveguide and the uniform diffraction grating are arranged at positions where the light emitting layer, the optical waveguide, and the uniform diffraction grating are optically coupled to one another, the uniform diffraction grating is arranged above the light emitting layer, the optical waveguide is arranged below the light emitting layer, and the optical waveguide includes, in the extending direction, a first portion having a predetermined width, a second portion having a larger width than the width of the first portion, and a third portion having the same width as the width of the first portion.

Abstract: A core, constituted by an amorphous undoped semiconductor (i type), which is formed on a lower clad layer, and a p-type layer and an n-type layer which are disposed on the lower clad layer with the core interposed therebetween and are formed in contact with the core are provided. The core is formed to be thicker than the p-type layer and the n-type layer. The p-type layer and the n-type layer are constituted by single crystal silicon.

Abstract: A silicon nitride core is formed on a silicon core via a first silicon oxide layer, and a germanium pattern caused to selectively grow in an opening penetrating through a second silicon oxide layer formed on the silicon nitride core and the first silicon oxide layer is formed on a lower silicon pattern formed to be continuous with the silicon core, thereby constituting a Ge photodiode.

Abstract: Included are an optical waveguide including a first cladding layer formed on a substrate; a core formed on the first cladding layer; and a second cladding layer formed on the first cladding layer so as to cover the core. At least one of the first cladding layer and the second cladding layer is composed of a cladding material of silicon oxide containing deuterium atoms. The number of hydrogen atoms contained in the cladding material is smaller than the number of the deuterium atoms contained in the cladding material.

Abstract: Provided is a tunable laser that prevents basic characteristics of the laser from deteriorating and enables a high-speed control of the oscillation wavelength. The tunable laser includes a semiconductor gain portion including a III-V compound semiconductor, an optical feedback portion configured to diffract light generated in the semiconductor gain portion and feed the diffracted light back to the semiconductor gain portion, and an optical modulation portion including an optical waveguide that contains doped indirect transition-type silicon. The semiconductor gain portion and the optical modulation portion are disposed so that optical modes thereof overlap each other, and the semiconductor gain portion includes an embedded active layer thin film of a type in which a current is injected in a lateral direction.

Abstract: An embodiment semiconductor optical device includes an optical waveguide including a core, and an active layer extending in the waveguide direction of the optical waveguide for a predetermined distance and arranged in a state in which the active layer can be optically coupled to the core. The core and the active layer are arranged in contact with each other. The core is formed of a material with a refractive index of about 1.5 to 2.2, such as SiN, for example. In addition, the core is formed to a thickness at which a higher-order mode appears. The higher-order mode is an E12 mode, for example.

Abstract: Included are an optical waveguide including a first cladding layer formed on a substrate; a core formed on the first cladding layer; and a second cladding layer formed on the first cladding layer so as to cover the core. At least one of the first cladding layer and the second cladding layer is composed of a cladding material of silicon oxide containing deuterium atoms. The number of hydrogen atoms contained in the cladding material is smaller than the number of the deuterium atoms contained in the cladding material.

Abstract: A wavelength tunable laser formed on a substrate made of single-crystal silicon is provided. The wavelength tunable laser includes a light emitting portion made of a III-V compound semiconductor, and external resonators provided with an optical filter. Cores included in the external resonators are made of one of SiN, SiON, and SiOn (n is smaller than 2).

Abstract: In a waveguide path coupling-type photodiode, a semiconductor light absorbing layer and an optical waveguide path core are adjacently arranged. An electrode formed of at least one layer is installed in a boundary part of the semiconductor light absorbing layer and the optical waveguide path core. The electrodes are arranged at an interval of (1/100)? to ? [?: wavelength of light transmitted through optical waveguide path core]. At least a part of the electrodes is embedded in the semiconductor light absorbing layer. Embedding depth from a surface of the semiconductor light absorbing layer is a value not more than ?/(2 ns) [ns: refractive index of semiconductor light absorbing layer]. At least one layer of the electrode is constituted of a material which can surface plasmon-induced.

Abstract: In a waveguide path coupling-type photodiode, a semiconductor light absorbing layer and an optical waveguide path core are adjacently arranged. An electrode formed of at least one layer is installed in a boundary part of the semiconductor light absorbing layer and the optical waveguide path core. The electrodes are arranged at an interval of (1/100)? to ? [?: wavelength of light transmitted through optical waveguide path core]. At least a part of the electrodes is embedded in the semiconductor light absorbing layer. Embedding depth from a surface of the semiconductor light absorbing layer is a value not more than ?/(2ns) [ns: refractive index of semiconductor light absorbing layer]. At least one layer of the electrode is constituted of a material which can surface plasmon-induced.

Abstract: An optical module includes an under cladding, a first core, a second core, and an over cladding. The under cladding has a flat shape as a whole. The first core has a quadrangular cross section and is placed on the under cladding. The second core is placed on a terminal end portion of the first core. The over cladding is placed in a region including the terminal end portion of the first core and the second core placed on the terminal end portion of the first core. The under cladding and the first core placed thereon constitute a first optical waveguide. The under cladding, the terminal end portion of the first core placed on the under cladding, the second core placed thereon, and the over cladding placed on and around the second core constitute a mode field size conversion portion. The under cladding, the second core placed on the under cladding, and the over cladding placed on and around the second core constitute a second optical waveguide. The first core is made of silicon.

Abstract: An optical module includes an under cladding, a first core, a second core, and an over cladding. The under cladding has a flat shape as a whole. The first core has a quadrangular cross section and is placed on the under cladding. The second core is placed on a terminal end portion of the first core. The over cladding is placed in a region including the terminal end portion of the first core and the second core placed on the terminal end portion of the first core. The under cladding and the first core placed thereon constitute a first optical waveguide. The under cladding, the terminal end portion of the first core placed on the under cladding, the second core placed thereon, and the over cladding placed on and around the second core constitute a mode field size conversion portion. The under cladding, the second core placed on the under cladding, and the over cladding placed on and around the second core constitute a second optical waveguide. The first core is made of silicon.