Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Other

Yokogawa Electric Corporation

Shin Kamei

Hiroshi Fukuda

Ken Tsuzuki

Kiyofumi Kikuchi

Makoto Jizodo

Takashi Saida

Yasuyuki Inoue

Tsutomu Kitoh

Toshikazu Hashimoto

Takuya Tanaka

Motohaya Ishii

Shunichi Soma

Shuichiro Asakawa

Shigeo Nagashima

Hiroshi Takahashi

Yuichi Suzuki

Shinji Mino

Manabu Oguma

Yohei Sakamaki

Mikitaka Itoh

Toshihiro Itoh

Akimasa Kaneko

Mitsuo Usui

Satoru Konno

Teruaki Sato

Tomohiro Nakanishi

Naoki Fujiwara

Hiroshi Yamazaki

Yasuyuki Suzuki

Masahiro Suzuki

Hiroshi Koizumi

Hideyuki Nosaka

Koichi Murata

Takayuki Mizuno

Makoto Abe

Kenya Suzuki

Hiroyuki Uzawa

Munehiko Nagatani

Hiroyuki Fukuyama

Takashi Goh

Makoto Komiyama

Kengo Horikoshi

Hiroto Kawakami

Hiroshi Hasegawa

Osamu Moriwaki

Nobuhiro Kikuchi

Hiroaki Katsurai

Ken-ichi Sato

Akira Himeno

Kotaro Takeda

Tomoyoshi Kataoka

Shigeki Aisawa

Kuniharu Kato

Tomohiro Shibata

Yoshinori Hibino

Yoshihisa Sakai

Senichi Suzuki

Yuriko Kawamura

Masafumi Nogawa

Takeshi Kitagawa

Mikio Yoneyama

Yoshihiro Sanpei

Daisuke Ogawa

Akihiro Takagi

Motoki Minami

Shuuhei Okada

Kenji Ogino

Masaki Kohtoku

Raiju Okada

Kouichi Takiguchi

Shoji Kakehashi

Yuji Moriya

Yves Bouvier

An optical circuit board which is mounted with a loop-back circuit for returning aligning light to the fiber array in the vicinity of the fiber array connection end. Since an aligning loop-back circuit can be formed in an optical waveguide pattern, a production cost does not increase in comparison to an optical circuit board of the related art. The aligning light combined from the optical fiber to the aligning port of the optical circuit board is returned to the optical fiber around the loop-back circuit. Therefore, it is possible to perform alignment using the returned light. That is, alignment can be performed while being mounted on a package without installing a light-reflecting film or mirror.

Optical device having a fiber array, and method of alignment thereof

A germanium photodetector which reduces a dark current without degradation of a photocurrent includes: a silicon substrate; a lower clad layer formed on the silicon substrate; a core layer formed on the lower clad layer; a p-type silicon slab formed in a part of the core layer and doped with a p-type impurity ion; p++ silicon electrode sections that are highly-doped with a p-type impurity and act as an electrode; and germanium layers which absorb light. The germanium photodetector further includes an upper clad layer, an n-type germanium region doped with an n-type impurity above the germanium layer, and an electrode. According to the present invention, two germanium layers are provided on the p-type silicon slab so as to miniaturize the area of the surface of the individual germanium layer in contact with the p-type silicon slab, so that the dark current due to threading dislocation can be reduced.

Photodetector

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 receiver is configured so as to be as less susceptible to noise as possible even in the case where high noise occurs inside an optical transceiver. The optical receiver includes a connection part that connects two photodiodes (PDs) constituting a dual photodiode and a transimpedance amplifier (TIA), wherein signal lines from the dual photodiode are surrounded by a conductor pattern that is not connected to each of the signal lines for each channel, and the conductor pattern is connected to a ground pattern on the transimpedance amplifier or a power source pattern for the PDs.

Optical receiver

A coherent optical mixer circuit is provided that can measure a phase error without requiring a step of cutting away a delay circuit. Odd-numbered or even-numbered two of four inputs of an 4-input-and-4-output multimode interference circuit are connected to an input mechanism. The four outputs of the multimode interference circuit are all connected to an output mechanism to the exterior. Other two inputs of the multimode interference circuit are connected to two monitor waveguides. One of the monitor waveguide is longer than the other to configure a light delay circuit. The monitor waveguides constituting the light delay circuit are connected to the respective outputs of a 2-branched light splitter. The 2-branched light splitter has an input connected to a monitor light input mechanism from the exterior via a monitor input waveguide.

Coherent optical mixer circuit

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

A one chip-integrated digital coherent polarization multiplexing optical transmission and reception circuit with optimal optical power distribution between sending and receiving is provided by using an optical power splitter having a branching ratio of a lower asymmetry property so that the unbalanced loss depending on the polarization path can be compensated. A polarization multiplexing optical transmission and reception circuit includes a polarization multiplexing optical transmission circuit, including: the first optical power splitter for branching the optical power of continuous light outputted from a light source; one polarization optical modulation circuit at the side of a path having a higher loss connected to one output of the first optical power splitter; the second optical power splitter connected to the other output of the first optical power splitter; and the other polarization optical modulation circuit connected to one output of the second optical power splitter.

Polarization multiplexing optical transmission circuit and polarization multiplexing optical transmission and reception circuit

The visual detection of a silicon optical circuit in a conventional technique depends on sensory decision by a human who visually conducts checking, and there has been limitation in completely detecting small flaws. The optical circuit of the present invention includes, in addition to an optical circuit that implements desired functions, an optical waveguide for flaw detection which surrounds the entire optical circuit and which is sufficiently proximate to the optical waveguide of the optical circuit and grating couplers connected to the optical waveguide for detection. Based on the transmission characteristic measurement of the optical waveguide for detection using the grating couplers, a flaw within each chip can be efficiently discovered in the state of a wafer before being cut into chips. A flaw can also be discovered hierarchically by providing individual optical waveguides for detection for respective chips and by further forming one common optical waveguide for detection over the plurality of chips.

Silicon optical circuit for flaw detection in an optical circuit element

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

The present invention provides an optical modulator including a substrate and a phase modulation portion on the substrate. The phase modulation portion includes an optical waveguide comprised of a first clad layer, a semiconductor layer that is laminated on the first clad layer and has a refraction index higher than the first clad layer and a second clad layer that is laminated on the semiconductor layer and has a refraction index lower than the semiconductor layer, a first traveling wave electrode, and a second traveling wave electrode. The semiconductor layer includes a rib that is formed in the optical waveguide in an optical axis direction and is a core of the optical waveguide, a first slab that is formed in the optical axis direction in one side of the rib, a second slab that is formed in the optical axis direction in the other side of the rib, a third slab that is formed in the first slab in the optical axis direction at the opposite side to the rib, and a fourth slab that is formed in the second slab in the optical axis direction at the opposite side to the rib. The first slab is formed to be thinner than the rib and the third slab, and the second slab is formed to be thinner than the rib and the fourth slab.

Optical modulator

Polarization rotators of conventional techniques require forming a silicon nitride layer, which is not employed in usual fabrication of a silicon waveguide circuit. In order to employ a polarization rotator function in an optical integrated circuit, a process of forming a silicon nitride layer is added just for that purpose. This increases the fabrication time and complicates the fabrication equipment. In a polarization rotator of the present invention, the waveguide width of a center core portion of a polarization converter is made small. Thus, the intensity of an optical wave does not concentrate only at the center core portion and is more influenced by structural asymmetry. With the configuration of the polarization rotator of the present invention, it is possible to efficiently cause polarization conversion with a structure including only a silicon waveguide and no silicon nitride layer or the like formed thereon.

Polarization rotator

An optical wavelength multi/demultiplexing circuit is provided in which temperature dependence at a transmission center wavelength remained in an athermalized AWG is compensated. An AWG according to an embodiment of the present invention is compensated for the main temperature dependence at the transmission center wavelength. The AWG comprises an optical splitter, a first and second arm waveguides, an optical mode combining coupler and a multimode waveguide between an input/output waveguide and a slab waveguide. The optical mode combining coupler couples fundamental mode light from the first arm waveguide as fundamental mode and the fundamental mode light from the second arm waveguide as first mode. The multimode waveguide is capable of propagating the fundamental and first mode light. This AWG is configured such that the temperature dependence remained in the arrayed waveguide grating is compensated by changing the optical path length difference between the first and second arm waveguides with temperature.

Arrayed waveguide grating

A interferometer type polarization beam combiner and splitter, which can combine or split polarized light over a wide band, is provided. The interferometer type polarization beam combiner and splitter includes: an optical splitter; an optical coupler; an optical path length difference imparting unit, which includes a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two input/output ports connected to the optical splitter; and two input/output ports connected to the optical coupler. A half-integer of a wavelength of &#x3bb;c is set as a normalized phase difference, for the optical path length difference imparting unit, between two polarization states, and means for generating a difference in refractive index dispersion is provided between the optical waveguides of the optical path length difference imparting unit, so that the change rate of the transmittance with respect to wavelength is suppressed for the two polarization states.

Wideband interferometer type polarization light beam combiner and splitter

An optical wavelength multi/demultiplexer having transmission characteristics with a higher rectangular degree than a conventional one includes an AWG and two-stage lattice circuit. An example of a two-stage lattice circuit according to the present invention includes an input waveguide, a third optical coupler, a third and fourth arm waveguides, a second optical coupler, a first and second arm waveguides, a first optical coupler, and output waveguides. The optical path length differences between the third and fourth arm waveguides and between the first and second arm waveguides are designed to be &#x394;L. The path passing the third and first arm waveguides differs by 2&#xb7;&#x394;L in optical length from that the fourth and second arm waveguides. The paths passing the third and second arm waveguides and passing the fourth and first arm waveguides differ by &#x394;L from that passing the fourth and second arm waveguides.

Optical wavelength multi/demultiplexer

Growing community of inventors

Atsugi, Japan

Shin Kamei