The Furukawa Electric Co., Ltd.

Mitsubishi Electric Corporation

Dkk-toa Corporation

Satoshi Arakawa

Akihiko Kasukawa

Masaki Funabashi

Takuya Ishikawa

Nariaki Ikeda

Takeharu Yamaguchi

Toshikazu Mukaihara

Nobumitsu Yamanaka

Michio Ohkubo

Norihiro Iwai

Yutaka Ohki

Takao Ninomiya

Ryusuke Nakasaki

Shunsuke Okuyama

Tatsuto Kurobe

A communication system () includes communication devices () to share common time after correction of synchronization error including a communication delay with each other via a network (). The communication device () includes a set time acquirer to acquire set time set by a user, a setter to set the set time as first system time, which is system time of the communication device (), and a time difference data transmitter to transmit time difference data, which indicates a time difference between the common time and the set time, to the communication device (). The communication device () includes a time difference data receiver to receive the time difference data, and a setter to set the sum of the common time and the time difference indicated by the time difference data as second system time, which is system time of the communication device ().

Communication system, communication device, and program

A first PHY () transmits and receives signals, at a physical layer, to and from a second PHY () in a communication device () through a communication cable (). The first PHY () is set as a clock master to transmit, to the second PHY (), a clock signal defining timing for transmitting and receiving signals. A device controller (), in response to detection of a set event, completes initialization of the first PHY () set as the clock master after completion of initialization of the second PHY () set as a clock slave.

Communication device, communication system, and recording medium

A slave unit that is a communication apparatus according to the present invention includes: a frame relaying unit that receives, among communication frames received by a reception port, a communication frame to be relayed to the other apparatus and outputs the received communication frame to a transmission port; a frame transmitting unit that generates a communication frame and outputs the communication frame to the transmission port; and a transmission-frame arbitrating unit that regulates output of the communication frame to the transmission port performed by the frame transmitting unit in a guard time that is a period including a time period in which arrival of the communication frame transmitted in a network in a fixed cycle is expected.

Communication apparatus and network system

A communication device includes a transmission port and a reception port communicating with other network units, a system bus I/F unit communicating with a synchronous target, n (n is an integer of 2 or more) delay counters counting a predetermined period of time, a delay-counter control unit that, upon receiving a synchronous packet input with a predetermined cycle from the reception port, causes the delay counters to count a cycle that is n times as long as the predetermined cycle and controls the delay counters such that counts of the delay counters are cleared at different timings, and a synchronous-pulse output unit outputting a synchronous pulse to the synchronous target through the system bus I/F unit when there is the counter whose count value after being cleared becomes equal to a synchronous-pulse output value.

Communication device, communication system, and synchronous control method

A semiconductor laser outputs a laser light from an output facet of a waveguide having an index waveguide structure, via a lens system. The waveguide includes, in order from a rear facet opposite to the output facet, a first narrow portion, a wide portion that is wider than the first narrow portion, a second narrow portion narrower than the wide portion, a first tapered portion formed between the first narrow portion and the wide portion, which expands toward the wide portion, and a second tapered portion formed between the wide portion and the second narrow portion, which narrows toward the second narrow portion. Each of the first narrow portion, the wide portion, and the second narrow potion has a uniform width.

Semiconductor laser with varied-width waveguide and semiconductor laser module including the same

To provide an oil type discrimination method and an oil type discriminator capable of accurately discriminating a type of oil even when light-shielding components exist in the oil and of preventing in advance erroneous discrimination of a mixture of oil. There are provided step Sin which the transmission spectrum of near infrared light is measured, step Sin which the transmission spectrum is converted into an absorbance spectrum, a first discrimination step Sin which between gasoline type and non-gasoline type is discriminated by comparing the difference in absorbance between two wavelengths existing in the vicinities of respective attribute wavelengths of predetermined chemical bonds with 0.0, step Sin which the first derivative spectrum of the absorbance is found, a second discrimination step Sin which a value, which is obtained by multiplying respective first derivative values of absorbance of at least four wavelengths existing in the vicinities of respective attribute wavelengths of predetermined chemical bonds by respective coefficients and further adding a constant to the sum, is compared with 0.0 and thus between regular gasoline and high-octane gasoline is discriminated, and a third discrimination step Sin which the difference in absorbance between two wavelengths existing in the vicinities of respective attribute wavelengths of predetermined chemical bonds is compared with 0.0 and thus between kerosene and diesel oil is discriminated.

Oil type discrimination method and oil type discriminator

An EA-DFB module including a DFB laser diode and an EA modulator formed on an InP first-conductivity-type substrate has a mesa stripe, a current blocking structure formed on both side surfaces of the mesa strip and a second InP cladding layer formed on top of the mesa stripe and the current blocking structure. The current blocking structure includes a Fe-doped semi-insulating film, a first conductivity-type buried layer and a carrier-depleted layer. The carrier-depleted layer reduces the parasitic capacitance at the boundary between the first-conductivity-type buried layer and the second InP cladding layer.

Optical device having a carrier-depleted layer

A monolithic semiconductor optical device with excellent temperature and modulation characteristics and associated method of manufacturing whereby the device has a semiconductor substrate, a semi-insulating buried heterostructure GaInAsP-based DFB laser; and either a buried ridge type AlGaInAs-based EA or a self aligned structure (SAS) AlGaInAs-based EA modulator.

Semiconductor optical device and method for fabricating same

A distributed feedback (DFB) semiconductor laser device has a multiple-quantum-well (MQW) structure and a diffraction grating formed in the MQW structure. The diffraction grating includes a grating structure formed in QW layers and a barrier layer of the MQW structure and an embedded layer embedded in the grating structure. One of the QW layers and the barrier layers has an etching rate lower than the etching rate of the other layers of the MQW structure and functions as an etching stop layer during etching of the MQW structure for forming the diffraction grating.

DFB semiconductor laser device

A quantum confinement Stark effect (QCSE) optical modulator has a ridge stripe including a current confinement structure. The current confinement structure includes an AlInAs layer which is subjected to selective oxidation of Al content in the AlInAs layer. The current confinement structure is such that a pair of Al-oxidized regions of the AlInAs layer sandwiches therebetween a central un-oxidized region.

Quantum-confinement stark effect optical modulator

Disclosed is a process of producing a semiconductor layer structure which emits lights with a plurality of luminescence wavelengths from the same quantum well structure. The layer structure has a layer structure which has the quantum well structure located between a lower light-confinement layer and an upper light-confinement layer. At least a part of the quantum well structure is an area which has a shorter luminescence wavelength than those of the other portions. This area is produced by stacking a lower cladding layer, the lower light-confinement layer, the quantum well structure, the upper light-confinement layer and a first semiconductor layer having a first conductivity type on a semiconductor substrate by epitaxial growth and further stacking a second semiconductor layer having the opposite conductivity type to that of the first semiconductor layer on the entire surface or a partial surface of the first semiconductor layer. This second semiconductor layer may be removed after the formation.

Process of producing semiconductor layer structure

A semiconductor light emitting diode (,) is formed on an n-type GaAs substrate and includes: an AlGaInP based double heterojunction structure in which an active layer (,) is sandwiched between cladding layers (,); an upper P-type contact layer,and a ring-shaped upper electrode (,) having an opening (,), wherein light is emitted through the upper p-type contact layer (,) and the opening (,) of the upper electrode (,). The upper p-type contact layer (,) is a semiconductor layer made of AlGaAs or AlGaAsP having an Al content of 0.5 or more, and doped with impurities at a carrier concentration of 5&times;10,cm,or more. The semiconductor light emitting diode emits light in a desired emission pattern and at higher intensities, and is capable of being fabricated by relatively simple processes.

Semiconductor light-emitting diode

A semiconductor laser is produced by forming a laser activation section and a light emitting section having an InGaAsP layer as a quantum well on a GaAs substrate according to metal organic chemical vapor deposition by using a selective area growth mask, in such a manner that the laser activation section and the light emitting section have different film thicknesses. The laser activation section includes a laser activation layer whose oscillation wavelength is set to 0.8 to 1.1 .mu.m, and the light emitting section includes an optical waveguide layer having a broader forbidden band than the laser activation layer.

Growing community of inventors

Tokyo, Japan

Satoshi Arakawa