Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Takashi Saida

Yasuhiro Hida

Hiroshi Fukuda

Naoki Fujiwara

Hiroshi Takahashi

Motohaya Ishii

Ken Tsuzuki

Tsutomu Kitoh

Masahiro Yanagisawa

Toshikazu Hashimoto

Takayuki Mizuno

Yasuyuki Inoue

Takashi Goh

Shin Kamei

Yohei Sakamaki

Senichi Suzuki

Hiroshi Yamazaki

Munehisa Tamura

Ryoichi Kasahara

Shinji Mino

Manabu Oguma

Kiyofumi Kikuchi

Mikitaka Itoh

Yusuke Nasu

Katsunari Okamoto

Shunichi Soma

Hiroshi Terui

Shuichiro Asakawa

Koichi Takiguchi

Mitsuo Usui

Yasuaki Hashizume

Tomoyo Shibazaki

Shigeo Nagashima

Yuichi Kikuchi

Masahiro Suzuki

Hiroshi Koizumi

Hideyuki Nosaka

Koichi Murata

Makoto Abe

Yuichi Suzuki

Kenya Suzuki

Hiroyuki Uzawa

Munehiko Nagatani

Hiroyuki Fukuyama

Kengo Horikoshi

Takashi Yamada

Hiroto Kawakami

Osamu Moriwaki

Nobuhiro Kikuchi

Ikuo Ogawa

Akira Himeno

Yuichiro Ikuma

Takashi Go

Akio Sugita

Hiroaki Katsurai

Toshihiro Itoh

Masayuki Okuno

Yoshiyuki Doi

Tomohiro Shibata

Tomoyoshi Kataoka

Shigeki Aisawa

Yoshinori Hibino

Masafumi Nogawa

Mikio Yoneyama

Fumihiro Ebisawa

Takao Fukumitsu

Atsushi Murasawa

Daisuke Ogawa

Satoru Konno

Teruaki Sato

Kentaro Honda

Tomohiro Nakanishi

Yuji Moriya

Masaki Kotoku

Koutaro Takeda

Yves Bouvier

A wavelength monitoring apparatus includes a wavelength monitoring circuit. The wavelength monitoring circuit includes: a split circuit that splits an input optical signal into two; an optical delay circuit that applies a delay time difference to the two split optical signals; and a two-input two-output optical multiplexer/demultiplexer circuit that outputs a result of applying multiplexing interference to the optical signals to which the delay time difference has been applied. The wavelength monitoring apparatus further includes photoelectric conversion elements that perform photoelectric conversions on the two optical signals output from the wavelength monitoring circuit so as to output electrical signals. The wavelength monitoring apparatus is configured to obtain the wavelength of the optical signal, by calculating a ratio between two electrical outputs of the photoelectric conversion elements and referring to a correspondence table indicating wavelengths of optical signals input to the wavelength monitoring circuit and ratios between electrical outputs.

Wavelength monitoring device and controlling method thereof

An optical module that is connectable to an optical fiber array and that can be packaged in a high density. Two package modules are mounted on a board, and optical waveguides in a Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block. Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. The optical waveguides in the Si photonic lightwave circuit may be tilted at an appropriate angle with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.

Optical module

An optical modulator that suppresses the chirp due to the mask offset, for example during the phase modulation, and that provides a high waveform quality includes: two RF electrodes for applying one pair of differential signal voltages; at least one fixed potential electrodes for applying a fixed potential; a first conductive semiconductor layer and a second conductive semiconductor layer abutted to the RF electrode or a fixed potential electrode; and a light modulation unit including two optical waveguides branched from one optical waveguide that are arranged along a pn junction unit functioning as a boundary between the first and second conductive semiconductor layers, wherein: the semiconductor layers and the electrode are provided so that the integration amounts of the phase changes caused by the offsets of the positions of the pn junction units in the two optical waveguides from a design value is equal between the two optical waveguides.

Optical modulator

An optical module that suppresses crosstalk between high-frequency transmission lines includes at least one set of: an optical port; an optical processing circuit optically connected to the optical port; an electro-optical transducer optically connected to the optical processing circuit; two or more high-frequency transmission lines connected to the electro-optical transducer; and electrical ports connected to the high-frequency transmission lines, and includes a conductive cover block which is provided above the high-frequency transmission lines so as to at least partly cover the high-frequency transmission lines and which is grounded.

An optical modulator driver circuit () includes an amplifier (, Q, Q, R-R), and a current amount adjustment circuit () capable of adjusting a current amount of the amplifier () in accordance with a desired operation mode. The current amount adjustment circuit () includes at least two current sources (IS) that are individually ON/OFF-controllable in accordance with a binary control signal representing the desired operation mode.

Optical modulator driver circuit and optical transmitter

In a conventional soldering method, an FPC-side electrode pad and a package-side electrode pad are closely joined together with a solder layer, and the soldered state after a joining process has not been easily confirmed visually. The present invention provides a solder joint structure including a side face electrode which is formed on each of the side faces of the end parts of an FPC board and a package or PCB board that are to be soldered, extending vertically relative to the faces constituting each of electrode pads on the boards, and which introduces solder. On the side face electrodes of the board end parts, a part of solder that is formed continuously from the solder joint portion is visible and the state of the solder joint between the electrode pads on the two boards can be confirmed. The efficiency of solder joint tests can be improved.

Solder joint structure of flexible printed circuit board

Provided is a waveguide-type polarization beam splitter in which deterioration of a polarization extinction ratio due to temperature change and wavelength change is suppressed. The waveguide-type polarization beam splitter includes: input optical waveguides; a first multimode interference optical coupler; a pair of optical waveguide arms; a second multimode interference optical coupler; and output optical waveguides. A quarter wavelength delay is provided in one of the pair of optical waveguide arms, a groove is formed to extend across both of the pair of optical waveguide arms, and two quarter wave plates are provided in the groove to extend respectively across the arms. Polarization axes of the respective quarter wave plates are orthogonal to each other.

Waveguide-type polarization beam splitter

Provided is a waveguide-type polarization beam splitter in which deterioration of a polarization extinction ratio due to temperature change and wavelength change is suppressed. A groove is formed to extend across a pair of optical waveguide arms and two quarter wave plates are provided in the groove to extend respectively across the arms. Polarization axes of the quarter wave plates are orthogonal to each other. A first optical coupler which gives a phase difference of 0&#xb0; or 180&#xb0; between coupled or split light beams and a second optical coupler which gives a phase difference of 90&#xb0; or &#x2212;90&#xb0; between coupled or split light beams are used in combination.

An optical modulator comprises an input optical splitting unit for bifurcating input light; a final optical coupling unit for coupling optical signals in a polarization state orthogonal to each other; an intermediate optical coupling unit provided in an intermediate position between the input optical splitting unit and the final optical coupling unit; first and second optical paths for connecting the input optical splitting unit and the intermediate optical coupling unit, optical path lengths of the first and second optical paths are approximately equal; third and fourth optical paths for connecting the intermediate optical coupling unit and the final optical coupling unit, optical path lengths of third and fourth optical paths are approximately equal; and three binary phase modulation unit arranged one by one in each of the three optical paths of the first, second, third and fourth optical paths.

An optical modulation circuit includes: a first Mach-Zehnder modulating portion including a first output port and a second output port, wherein the first Mach-Zehnder modulating portion is push-pull driven by a main signal; a second Mach-Zehnder modulating portion connected to the first output port of the first Mach-Zehnder modulating portion, wherein the second Mach-Zehnder modulating portion is push-pull driven by a correction signal; and an asymmetric light combining portion combining an optical signal outputted from an output port of the second Mach-Zehnder modulating portion with an optical signal outputted from the second output port of the first Mach-Zehnder modulating portion in a light intensity coupling ratio of r to 1&#x2212;r, wherein an optical path length from the first output port to the asymmetric light combining portion is substantially equal to an optical path length from the second output port to the asymmetric light combining portion.

Light modulation circuit

An optical component has first and second planar lightwave circuits. The first and second planar lightwave circuits are aligned and jointed such that the position of an i-th optical waveguide (where i is an integer greater than or equal to 1 and less than or equal to n) of the first planar lightwave circuit and that of an i-th optical waveguide of the second planar lightwave circuit are matched on a joint interface. An angle formed by the i-th optical waveguide of the first planar lightwave circuit and a normal of the interface is configured to vary in accordance with a value of i within a range satisfying the Snell's law.

Optical component having different waveguide angles at the interface between two planar lightwave circuits

An object of the present invention is to provide a temperature-independent optical frequency shifter for generating sub-carriers with a miniaturizable configuration, as well as to provide an all-optical OFDM modulator using the same that is compact, has low temperature dependence, and is even compatible with different frequency grids. Provided is an optical frequency shifter and an optical modulator using the same, the optical frequency shifter comprises one input optical port, a 1-input, 2-output optical coupler optically connected thereto, two Mach-Zehnder modulation units individually optically connected to the two outputs thereof, a 2-input, 2-output optical coupler optically connected to the individual outputs thereof, and two output optical ports optically connected to the outputs thereof, wherein the two Mach-Zehnder modulation units are driven by periodic waveforms at the same frequency whose phases differ from each other by (2p+1)&#x3c0;/2 (p: integer).

Optical frequency shifter and optical modulator using the same

In an optical component configured to fix to a mount an optical device chip in which waveguide type optical devices having different thermal expansion coefficients are butt-jointed, deterioration in reliability due to thermal stress is suppressed. The optical component () comprises an optical device chip () including an LN waveguide (), a first PLC waveguide (), a second PLC waveguide (), and a fiber alignment member (), a mount (), and optical fibers (). Each of connection faces between the first PLC waveguide and the fiber alignment member is configured as an tilted structure, and each of connection faces between the LN waveguide, and the first and second PLC waveguides is configured as a right-angled structure. In the right-angled structure, the connection faces are connected by an adhesive having a lower Young's modulus than that of an adhesive used on the connection faces of the tilted structure.

Optical component

A planar lightwave circuit is provided which can be easily fabricated by an existing planar-lightwave-circuit fabrication process, which can lower the propagation loss of signal light and which can convert inputted signal light so as to derive desired signal light. A planar lightwave circuit having a core and a clad which are formed on a substrate, has input optical waveguide(s) () which inputs signal light, mode coupling part () for coupling a fundamental mode of the inputted signal light to a higher-order mode and/or a radiation mode, or mode re-coupling part () for re-coupling the higher-order mode and/or the radiation mode to the fundamental mode, and output optical waveguide(s) () which outputs signal light. The mode coupling part or the mode re-coupling part is an optical waveguide which has core width and/or height varied continuously.

Planar lightwave circuit, design method for wave propagation circuit, and computer program

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Atsugi, Japan

Takashi Saida