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Nippon Telegraph & Telephone Corporation Patents
Nippon Telegraph & Telephone Corporation
Tokyo, JP
No. of patents:

1 2 3

Patent Number Title Of Patent Date Issued
RE34972 Optical fiber evaluation method and system June 20, 1995
Use is made of a non linear interaction between a first modulated signal light from a first light source and a second signal light from a second light source which propagate in an optical fiber to be examined in opposite directions, i.e., so-called Brillouin light amplification, to a
7792430 Automatic power restoring method and optical communication system September 7, 2010
The present invention provides an automatic power restoring method capable of reliably detecting continuity by the dissolution of a line fault, to restore the optical power, even in a structure including an optical amplification medium on an optical transmission path and an optical c
7536108 High precision chromatic dispersion measuring method and automatic dispersion compensating optic May 19, 2009
The present invention relates to an automatic dispersion compensating optical link system. Carrier suppressed RZ encoded optical signals generated using carrier suppressing means and binary NRZ code or partial response code, or carrier suppressed clock signals generated using carrier
7496100 Method and apparatus for synchronous frame communication February 24, 2009
A method and apparatus for synchronous frame communication first communicates a frame signal having communication data and first control information having a bit length and an SDH frame structure in a part of frame time interval and a control information processing method based on an
7490107 Information search method and apparatus of time-series data using multi-dimensional time-series February 10, 2009
It enables easy and quick searching and delivery of information desired by a user based upon a portion of time-series data which consists of clip information from music, a movie, a commercial message, or the like. The user accesses an information search server from a user terminal which
7483446 Packet transmission device and packet transmission system January 27, 2009
The present invention discloses a packet transmission device and a packet transmission system which can realize high-capacity communication. The transmission device transmits packets over a wavelength division multiplexing (WDM) link by mapping the packets into an optical path signal
7400800 Arrayed waveguide grating type optical multiplexer/demultiplexer circuit July 15, 2008
An arrayed waveguide grating type optical multiplexer/demultiplexer circuit in which wavelength dispersion is reduced. An input wave guide (1), a first slab waveguide (2), an arrayed waveguide (3), a second slab waveguide (4) and an output waveguide (5) are connected sequentially. Fu
7341381 Optical connector March 11, 2008
A cantilever type latch having the fixed end on the side of exposing the terminal end surface of the optical fiber is provided on the side of the plug housing. Near the center of the upper surface of the latch, an engaging projection which is to be engaged in the engaging hole formed in
7313596 Multicast data communication method, multicast data communication system, repeater, repeating me December 25, 2007
A multicast data communication system is provided that has high security, and prevents problems such as an attack by a malicious user creating a great number of meaningless tables at nodes in the network. Clients regularly transmit request packets toward a server; a node receives the
7262905 Optical amplifier August 28, 2007
An optical amplifier includes a first optical path, second optical path, semiconductor optical amplifier, and multi-mode interference 3-dB coupler. The first optical path guides oscillation light. The second optical path guides signal light. The semiconductor optical amplifier causes
7110652 Optical waveguide and method of manufacture September 19, 2006
An optical waveguide capable of having various characteristics and a method of manufacture thereof as well as a method of manufacturing a crystal film are provided. An optical functional material KTa.sub.xNb.sub.1-xO.sub.3 is used as an optical waveguide. The input optical signal is
7088501 Optical amplifier August 8, 2006
An optical amplifier includes a first optical path, second optical path, semiconductor optical amplifier, and multi-mode interference 3-dB coupler. The first optical path guides oscillation light. The second optical path guides signal light. The semiconductor optical amplifier causes
7002532 Three-dimensional representation method and an apparatus thereof February 21, 2006
A three-dimensional representation method for generating a three-dimensional image by displaying two-dimensional images on a plurality of image planes located at different depth positions wherein two-dimensional images are generated in which an object to be presented is projected, al
6990131 Semiconductor optical device and method of manufacturing the same January 24, 2006
A semiconductor optical device includes a multilayer structure and buried layers. The multilayer structure is constituted by a cladding layer having an n-type conductivity, an active region formed from an active layer or photoabsorption layer, and a cladding layer having a p-type con
6978073 Optical fiber array December 20, 2005
An optical fiber array includes an alignment substrate, a plurality of ferrules, and a plurality of optical fibers. The alignment substrate has a plurality of guide holes which are two-dimensionally arrayed and extend through the substrate. The ferrules are respectively inserted into the
6947893 Acoustic signal transmission with insertion signal for machine control September 20, 2005
The acoustic signal transmission includes electrically synthesizing an audible sound signal and an insertion signal to generate a synthesized sound electrical signal at the sending side, transmitting the synthesized sound electrical signal, and extracting the insertion signal form the
6931537 Folder type time stamping system and distributed time stamping system August 16, 2005
In a time stamping system formed by a client device and a server device, the client device includes a digest generation unit for generating a plurality of digests for a plurality of digital documents, a digest combining unit for combining the plurality of digests generated by the dig
6920166 Thin film deposition method of nitride semiconductor and nitride semiconductor light emitting de July 19, 2005
A masking material 13, which includes stripe-like openings 12 parallel to the [1-100] direction of a nitride semiconductor thin film, is formed on a substrate. Nitride semiconductor thin films 11 doped with Mg are grown on the openings 12 by selective-area growth. The nitride semiconduct
6900885 White light source May 31, 2005
The present invention relates to a white light source. This white light source comprises a plurality of amplified spontaneous emission light generating sections each comprising at least an active fiber. At least two of the amplified spontaneous emission light generating sections are
6811728 Multi-layered holographic read-only memory and data retrieval method November 2, 2004
An inexpensive multi-layered holographic read-only memory having a large capacity is provided. In the memory in which single-mode slab waveguides are multi-layered, a periodic scattering center whose period approximately agrees with the period of the guided mode is provided in at least o
6778754 Optical fiber wiring apparatus and optical fiber wiring method August 17, 2004
A wiring substrate; a wiring head which guides optical fibers to the lead end thereof and forms an optical fiber path; an optical fiber feed mechanism which feeds the optical fiber into the optical fiber path; an optical fiber contact mechanism which brings the optical fiber, which has
6753996 Light-controlled light modulator June 22, 2004
A light-controlled light modulator can achieve high-speed, low-loss wavelength conversion. Continuous light with a wavelength .lambda.j is launched into an MMI coupler via a port, and is split into two parts by the MMI coupler, which are led to a loop-type interferometer. In the loop
6729541 Information reading apparatus and information recording medium May 4, 2004
An information reading apparatus can detect the coupling state of the input light to a waveguide of a laminated recording medium in a simple manner, so as to enable to focus the input light on a target recording layer to access the information recorded in the target recording layer quick
6720548 Optical sampling waveform measuring apparatus aiming at achieving wider band April 13, 2004
A nonlinear optical crystal is composed of 2-adamantyl-5-nitorpyridine (AANP) allowing the type 2 phase matching to the sampling light and a measuring object light, emitting a sum frequency light of the measuring object light and the sampling light, with the polarization directions t
6697395 Sum frequency light generation method and sum frequency light generation apparatus adapatble for February 24, 2004
A nonlinear optical crystal allowing type 2 phase matching multiplexes a fixed wavelength light having an angular frequency .omega..sub.D and a variable wavelength light having an angular frequency .omega..sub.S, with the polarization directions thereof being perpendicular to each other,
6690952 Adaptive array antenna transceiver apparatus February 10, 2004
An adaptive array antenna transceiver apparatus provides: a local signal generator 24 that outputs a signal having a frequency that corresponds to the difference between the reception frequency and the transmitting frequency; a coupler 15 that separates and extracts a part of the signals
6685475 Learning control information generation method, apparatus and computer readable medium storing l February 3, 2004
A learning control information generation method in a web-based training system which uses the WWW for education is provided. The learning control information generation method includes the steps of specifying hypertext information which is processed first, requesting and obtaining the
6658149 Scheme for identifying gray-scale image December 2, 2003
A scheme for identifying input gray-scale image data (F) having noise tolerance and distortion tolerance. The data (F) is composed of a set of gray levels representative of points that form an image. In this scheme, weighting coefficient based on interpoint distances between each point o
6598092 Trunk transmission network July 22, 2003
In a trunk transmission network for transmitting information signals between nodes via paths, flexible path operation is achieved by setting up paths between source nodes and destination nodes after pre-classifying paths into a higher service class in which any loss of information oc
6570874 ATM switch May 27, 2003
An ATM switch includes a plurality of stages in which each stage has basic switches and the stages are interconnected. The ATM switch includes M.times.N basic switches per each stage and a part for interconnecting between the stages. The M.times.N basic switches are divided into N gr
6513038 Scheme for accessing data management directory January 28, 2003
There is disclosed a scheme for accessing data management directory which is capable of achieving easy and flexible data access which are managed in substantial directories from respective applications by constructing substantial directories which sort and manage the location of data
6396974 Optical switch May 28, 2002
An optical switch of the present invention has a plurality of elements arranged in each of a row and a column direction thereof, where the slits of each element are located at corresponding crossing point between an optical wave guide extending to a row direction and a column direction.
6396926 Scheme for fast realization of encrytion, decryption and authentication May 28, 2002
A new scheme for fast realization of encryption, decryption and authentication which can overcome the problems of the RSA cryptosystem is disclosed. The encryption obtains a ciphertext C from a plaintext M according to C.ident.M.sup.e (mod n) using a first secret key given by N (.gto
6370169 Method and apparatus for controlling optical wavelength based on optical frequency pulling April 9, 2002
Optical wavelength control method and apparatus which are capable of controlling an optical wavelength of a light source with a central wavelength which is uncertain and unstable at nanometer order is disclosed. In the optical wavelength control apparatus, the control target light en
6330699 Error compensating method and apparatus and medium storing an error compensating program December 11, 2001
An object of the present invention is to improve the transmission efficiency and reduce circuit size in error compensating techniques where bit errors occurring during transmission are compensated for by retransmission.Transmission equipment get sequence number(s) from control informatio
6320888 Frequency stabilized laser and method for preparing thereof November 20, 2001
A frequency stabilized laser using an integrated external cavity, comprising a semiconductor laser diode and an optical waveguide installed on the same substrate, and having an optically induced grating formed in the optical waveguide suppresses mode hopping due to a temperature change
6297650 Electrooptic probe October 2, 2001
The present invention relates to an electrooptic probe that couples an electrical field generated by a measured signal and an electrooptic crystal, makes light incident on this electrooptic crystal, and measures the waveform of the measured signal by the state of the polarization of
6260027 Electronic ticket system, collecting terminal, service providing terminal, user terminal, electr July 10, 2001
A collecting agency supplies a collecting agency name and a money bag number to a service providing terminal. In response to dealing requests from user terminals, the service providing terminal sends, to the user terminals, information which contains the collecting agency name (Id) and
6246760 Subband echo cancellation method for multichannel audio teleconference and echo canceller using June 12, 2001
In a subband echo cancellation for a multichannel teleconference, received signals x.sub.1 (k), x.sub.2 (k), . . . , x.sub.I (k) of each channel are divided into N subband signals, an echo y(k) picked up by a microphone 16.sub.j after propagation over an echo path is divided into N subba
6239645 Complementary tuned mixer May 29, 2001
A mixer circuit for frequency conversion operates with low power supply voltage lower than 1 V. The circuit comprises a first pair of N-channel MOS transistors and a second pair of N-channel MOS transistors each receiving differential local frequency signal, and a third pair of P-cha
6229882 Communications system using portable recording medium May 8, 2001
By using an external portable recording medium that stores a personal ID, a communications apparatus automatically transmits the personal ID and its own terminal identification information to a center apparatus. The center apparatus manages the personal ID and the terminal identification
6225827 Dynamic logic circuit and self-timed pipelined datapath system May 1, 2001
A dynamic logic circuit comprising a plurality of unit dynamic logic circuits sequentially coupled in a multiple-stage fashion, each of which unit dynamic logic circuits including: a logic circuit portion formed by one or more than one MOS transistors; a first MOS transistor for a pr
6212570 Information distribution device selection system April 3, 2001
An information distribution device selection system capable of selecting one information distribution device that is logically closest from the user communication terminal among a plurality of information distribution devices on inter-connected communication networks is disclosed. The sy
6181805 Object image detecting method and system January 30, 2001
In a dictionary image generating section, images of objects each belonging to any one of L categories are taken by a camera from predetermined M directions, a matching region of the object to be recognized is extracted from each of the object images, and dictionary images (N=L.times.M, n
6178158 Method and apparatus for transmission and reception January 23, 2001
In a method for transmission and reception over N transmission channels, the transmitting side performs orthonormal transform processing of N-channel modulated signals so that the resulting transformed output signals have lower cross-correlation, and the transformed N-channel signals
6161124 Method and system for preparing and registering homepages, interactive input apparatus for multi December 12, 2000
A method for preparing and registering homepages within a system that connects a plurality of user terminals with a server equipped by a service provider comprising the steps at said user terminals: editing and preparing homepages; transmitting the prepared homepage data to above ser
6154809 Mathematical morphology processing method November 28, 2000
A two-dimensional PE (processing element) array that can achieve a small amount of hardware, short transfer time and high flexibility. It includes q.times.r CAMs, where q and r are any integers equal to or greater than two, and hit-flag lines. Each CAM has one-dimensionally arrayed w wor
6127200 Vertical-cavity surface-emitting laser and method for manufacturing the same October 3, 2000
A vertical-cavity surface-emitting semiconductor laser has first and second semiconductor multi-layered films, an active layer, and third and fourth semiconductor multi-layered films which are piled up on a GaAs substrate in that order. Furthermore, the first film is formed by piling up
6122419 Optical signal processing apparatus and optical signal processing method September 19, 2000
The present invention relates to an optical signal processing apparatus and optical signal processing method which enable generation, waveform shaping, waveform measurement, waveform recording, correlation processing, and the like of optical pulses of 1-10 ps. A basic construction of the
6101021 Optical pulse generator August 8, 2000
According to the present invention, damage to a photo-detector disposed in clock signal extractor by means of an optical pulse having an optical power exceeding a rated value is prevented. A ring resonator generates a repetitive, high-frequency optical pulse. Optical branching circuit
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