Fujikura Limited

Agency for Science, Technology and Research

Kazuhiro Goi

Kensuke Ogawa

Hiroyuki Kusaka

Akira Oka

Norihiro Ishikura

Guo-Qiang Patrick Lo

Ning Guan

Shinichi Sakamoto

Ken Sakuma

Ryokichi Matsumoto

Mingbin Yu

Yong Tsong Tan

Hwee Gee Teo

Katsuhiro Takenaga

Xiaoguang Tu

Tsung-Yang Liow

Hitoshi Uemura

Kenji Oda

Hiroki Ishihara

An optical device includes: a first port group P including n ports P; a second port Q; and a wavelength multiplexer/demultiplexer disposed between the first port group P and the second port Q. In a case where light beams Lof predetermined different n wavelengths &#x3bb;corresponding to the respective ports Pare inputted to the wavelength multiplexer/demultiplexer, the wavelength multiplexer/demultiplexer combines the light beams Linto light L and outputs the light L to the second port Q. In a case where light L' is inputted to the second port Q, the wavelength multiplexer/demultiplexer separates the light L&#x2032; into light beams L&#x2032;of the wavelengths &#x3bb;and outputs the light beams L&#x2032;to the corresponding ports P.

Optical device, wavelength division multiplexing transmitter, wavelength division multiplexing receiver, and wavelength division multiplexing transmission and receiving system

A substrate-type optical waveguide includes: a mode conversion section including a first input light guide path and a first output light guide path; and a polarization conversion and multiplexing section including a second input light guide path and a second output light guide path. The mode conversion section converts light input into the first input light guide path into either: a superposition of a first TE fundamental mode and a first TE higher mode; or a superposition of a first TM fundamental mode and a first TM higher mode. The polarization conversion and multiplexing section converts either: the superposition of the first TE fundamental mode and the first TE higher mode; or the superposition of the first TM fundamental mode and the first TM higher mode, into a superposition of a second TE fundamental mode and a second TM fundamental mode.

Substrate-type optical waveguide and introducing method using fundamental and higher TE/TM modes

Provided is a semiconductor optical integrated circuit which consumes less electric power than a conventional semiconductor optical integrated circuit. A semiconductor optical integrated circuit () includes a semiconductor layer () in which (i) an optical waveguide (LG) including heated section Ithrough Iand (ii) heater parts Hand Hare provided. The optical waveguide (LG) meanders such that the heated sections Ithrough Iare juxtaposed to one another. Each heater part Hi is arranged between a heated section Ii and a heated section Ii+1 which are adjacent to each other.

Semiconductor optical integrated circuit

In order to reduce a high frequency loss of a substrate-type optical waveguide without facilitating, in a low frequency domain, a reflection by an entrance end of a traveling-wave electrode, the substrate-type optical waveguide includes a coplanar line, provided on an upper surface of an upper cladding, which includes (i) a traveling-wave electrode connected to a P-type semiconductor region and (ii) an earth conductor connected to an N-type semiconductor region. The traveling-wave electrode and the earth conductor are provided so that a distance D therebetween decreases as a distance from an entrance end of the traveling-wave electrode increases.

Substrate-type optical waveguide and substrate-type optical modulator

A light modulation element constituted by a substrate type optical waveguide has a Mach-Zehnder interferometer; and a traveling wave electrode having a signal electrode arranged at least between a first phase modulator and a second phase modulator and electrically connected to both of the first phase modulator and the second phase modulator. A polarity of a semiconductor region of the first phase modulator connected to the signal electrode and a plurality of a semiconductor region of the second phase modulator connected to the signal electrode are different from each other.

Light modulation element

An optical transmission device includes a plurality of transmitting/receiving units provided on a substrate, each transmitting/receiving unit includes: an optical transmitter; an optical receiver; a polarization combiner/splitter; and a connection portion. In the connection portions which are arranged at the positions symmetrical to each other, a direction opposite, with respect to a virtual symmetry axis, to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from one of the connection portions to an outside is substantially orthogonal to a direction of a main electric field on a plane perpendicular to an emission direction of an optical wave of the connection portion which is emitted from the other of the connection portions to an outside.

Optical transmission device and bidirectional optical transmission device

An optical waveguide device includes a substrate; a lower cladding disposed on the substrate; a rib waveguide including a slab disposed on the lower cladding and a single rib disposed on the slab contiguous to the slab; and an upper cladding disposed on the rib waveguide. The rib waveguide includes a first doped region having a first electric conductivity exhibiting a P-type electric conductivity across the rib and the slab and a second doped region being contiguous to the first doped region and having a second electric conductivity exhibiting an N-type electric conductivity across the rib and the slab.

Optical waveguide device and method of manufacturing the same

A bidirectional optical transmission apparatus includes a first optical waveguide device, a second optical waveguide device, and a polarization-maintaining optical fiber that connects the first optical waveguide device and the second optical waveguide device. A direction of a slow axis of the polarization-maintaining optical fiber with respect to a first substrate at a connecting portion between the first optical waveguide device and the polarization-maintaining optical fiber and a direction of the slow axis of the polarization-maintaining optical fiber with respect to the second substrate at a connecting portion between the second optical waveguide device and the polarization-maintaining optical fiber are substantially orthogonal to each other.

Polarization-maintaining optical fiber and bidirectional optical transmission apparatus

Provided is a light combining/dividing element which allows generation of reflected light to be suppressed, as compared with a conventional light combining/dividing element. A core of the light combining/dividing element includes an MMI part which is connected to a first core and to each of a second core and a third core. A width of a rib of a rib waveguide of the MMI part becomes narrower from a width equal to that of a channel waveguide to a width equal to that of the first core.

Light combining/dividing element and light modulator

Provided is a substrate-type optical waveguide, having a phase modulation function, (i) in which a reflection of a signal to be inputted via a coplanar line is restrained and (ii) which consumes less power. In a case where the substrate-type optical waveguide is partitioned into a plurality of sections by cross sections orthogonal to a direction in which light propagates through a core, a local capacitance in each of the plurality of sections gradually increases as a distance from an entrance end surface increases.

An optical waveguide device includes: a mode splitter including a main waveguide in which lights can be propagated in at least two propagation modes with different propagation orders and a subsidiary waveguide which includes a coupling section disposed in parallel with the main waveguide at a certain distance away from the main waveguide so as to constitute a directional coupler and is capable of splitting at least one propagation mode out of the two or more propagation modes from the main waveguide. Also, n/nwhich is a refractive index ratio between a core and a cladding which constitute the main waveguide and the subsidiary waveguide is in a range of 101% to 250%.

Optical waveguide device having a light absorber for split out modes

An optical waveguide element includes a core and a cladding that is made of SiO. When nis a group refractive index of a TEpolarized wave in the i-th waveguide counted from a light incidence plane of the core and nis a group refractive index of a TMpolarized wave in the i-th waveguide, the length L[m] of the i-th waveguide satisfies a predetermined relation.

Optical waveguide element, light-receiving device, optical communication device, optical modulator, optical resonator, and method for manufacturing optical waveguide element

An optical modulation device configured of a planar optical waveguide, includes: a light incidence unit which allows light to be incident on the planar optical waveguide; a Mach-Zehnder interferometer which includes a first optical splitter section branching the light incident on the light incidence unit, two arm portions guiding the light branched by the first optical splitter section, a phase modulation unit linearly disposed on each of the two arm portions, and a first optical coupler section combining the light guided from the two arm portions; a light launching unit which launches the light combined by the first optical coupler section from the planar optical waveguide; and a traveling-wave electrode which includes an input unit and an output unit, and applies a voltage to the phase modulation unit.

Optical modulation device

A high-order polarization conversion device configured of a planar optical waveguide, includes: a substrate; a lower clad disposed on the substrate; a core including a lower core and an upper core, the lower core being disposed on the lower clad and having a fixed height in a rectangular sectional shape, the upper core being formed of the same material as the lower core and having a fixed height in a rectangular sectional shape that is disposed continuously on the lower core; and an upper clad that is disposed on the core and the lower clad and is formed of the same material as the lower clad. The high-order polarization conversion device performs high-order polarization conversion between TEof the start portion and TMof the end portion.

High-order polarization conversion device, optical waveguide device, and DP-QPSK modulator

A polarization conversion element is disclosed in which an optical waveguide formed on a substrate sequentially includes a first waveguide portion, a polarization rotation portion, and a second waveguide portion, an effective refractive index of a TE mode having the highest effective refractive index in an eigen mode of waveguide light on a sectional surface of the first waveguide portion is higher than an effective refractive index of a TM mode having the highest effective refractive index, an effective refractive index of the TM mode having the highest effective refractive index on a sectional surface of the second waveguide portion is higher than an effective refractive index of the TE mode having the highest effective refractive index, and heights of waveguide structures (for example, cores) of the first waveguide portion and the second waveguide portion are equal to each other.

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Sakura, Japan

Kazuhiro Goi