Takao Naito

US Patent:

7522838, Apr 21, 2009

Filed:

Feb 3, 2006

Appl. No.:

11/347585

Inventors:

Martin Bouda - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04J 14/00

US Classification:

398 72, 398 58, 398 66

Abstract:

In accordance with the teachings of the present invention, distribution components for a wavelength-sharing network are provided. In a particular embodiment, a distribution node for an optical network includes a first distributor operable to receive a first downstream signal comprising at least traffic in a first wavelength and traffic in a second wavelength from an upstream terminal, route the traffic in the first wavelength to a first plurality of downstream terminals, and route the traffic in the second wavelength to a second plurality of downstream terminals. A second distributor is operable to receive a second downstream signal comprising at least traffic in a third wavelength, and forward the traffic in the third wavelength to at least the first plurality of downstream terminals. A first combining element is operable to receive the traffic in the first wavelength from the first distributor, receive the traffic in the third wavelength from the second distributor, and forward the traffic in the first wavelength and the traffic in the third wavelength to the first plurality of downstream terminals. A second combining element operable to receive at least the traffic in the second wavelength from the first distributor and forward the traffic in the second wavelength to the second plurality of downstream terminals.

US Patent:

7539360, May 26, 2009

Filed:

Sep 23, 2005

Appl. No.:

11/233650

Inventors:

Cechan Tian - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

G02F 1/295
G02B 6/12
G02B 6/26

US Classification:

385 4, 385 15, 385 14

Abstract:

Monitoring a bias point of an optical modulator includes receiving an optical signal modulated by the optical modulator. Photons of the optical signal are received at a photon reactive material operable to produce a reaction in response to the arrival of a predetermined number of photons. Reactions are produced in response to the arrival of the photons of the optical signal. Feedback is generated in response to the reactions. The feedback reflects the waveform of the optical signal, and indicates one or more bias points of the optical modulator.

US Patent:

7546036, Jun 9, 2009

Filed:

Feb 3, 2006

Appl. No.:

11/347434

Inventors:

Martin Bouda - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04J 14/00

US Classification:

398 72, 398 63, 398 71

Abstract:

In accordance with the teachings of the present invention, a hybrid passive optical network using shared wavelengths is provided. In a particular embodiment, a system for communicating optical signals over a network includes an upstream terminal. The upstream terminal includes a signal source operable to transmit a downstream signal comprising at least traffic in a first wavelength and traffic in a second wavelength. The upstream terminal is operable to receive upstream traffic in a third wavelength, wherein the third wavelength is shared by a first plurality of downstream terminals and a second plurality of downstream terminals. The system also includes a distribution node comprising a wavelength router. The wavelength router is operable to receive the downstream signal, route the traffic in the first wavelength to the first plurality of downstream terminals, and route the traffic in the second wavelength to the second plurality of downstream terminals.

US Patent:

7603036, Oct 13, 2009

Filed:

Oct 25, 2006

Appl. No.:

11/552696

Inventors:

Paparao Palacharla - Richardson TX, US
Martin Bouda - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04J 14/00
H04J 4/00

US Classification:

398 72, 398 75

Abstract:

A method includes transmitting, at a first wavelength, a first configuration message on the PON including a first transmitter interface number and transmitting, at a second wavelength, a second configuration message on the PON including a second transmitter interface number. The method further includes receiving a configuration response message from a first set of ONUs that comprises the first transmitter interface number and from a second set of ONUs that comprises the second transmitter interface, associating the first set of ONUs with the first wavelength and the second set of ONUs with the second wavelength, and transmitting downstream traffic destined for any ONU in the first set of ONUs at the first wavelength and transmitting downstream traffic for any ONU in the second set of ONUs at the second wavelength.

US Patent:

7650083, Jan 19, 2010

Filed:

Jun 30, 2006

Appl. No.:

11/479836

Inventors:

Cechan Tian - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04B 10/06

US Classification:

398202, 398188, 398183, 398204, 398207

Abstract:

A demodulator includes one or more modules operable to receive an input signal comprising symbols. A module receives a main signal comprising at least a portion of the input signal and splits the main signal to yield a branching signal and a remaining main signal. The branching signal travels along a first path, and the remaining main signal travels along a second path. The second path introduces a delay with respect to the first path. If there is a next module, the module sends a first portion of the remaining main signal to a next module as a main signal for the next module. The module combines the branching signal and at least a second portion of the remaining main signal to generate interference. The interference indicates a phase shift between a phase corresponding to a symbol and a successive phase corresponding to a successive symbol.

US Patent:

7653124, Jan 26, 2010

Filed:

Oct 3, 2006

Appl. No.:

11/538158

Inventors:

Cechan Tian - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04B 3/46

US Classification:

375224

Abstract:

Monitoring a demodulator includes repeating the following for each demodulating module of one or more demodulating modules of a demodulator: receiving a first signal and a second signal from a demodulating module; introducing a relative delay between the first signal and the second signal; and asynchronously sampling the first signal and the second signal to yield samples. Image data representing the samples associated with the demodulating modules is generated. The image data indicates one or more mismatches of the demodulator.

US Patent:

7668466, Feb 23, 2010

Filed:

Jun 30, 2006

Appl. No.:

11/479920

Inventors:

Cechan Tian - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsui Limited - Kawasaki

International Classification:

H04B 10/06

US Classification:

398202, 398188, 398161, 398102, 398212, 398213

Abstract:

A demodulator comprises an input splitter, optical device sets, and couplers. The input splitter splits an input signal comprising symbols to yield a number of signals. A first optical device set directs a signal of along a first path. A second optical device set directs another signal along a second path to yield a delayed signal. At least a portion of the second path is in free space. A path length difference between the first path and the second path introduces a symbol delay between the first signal and the second signal. A coupler receives a portion of the signal and a portion of the delayed signal to generate interference, where the interference indicates a phase shift between a phase corresponding to a symbol and a successive phase corresponding to a successive symbol.

US Patent:

7684706, Mar 23, 2010

Filed:

Jun 27, 2006

Appl. No.:

11/426884

Inventors:

Yoichi Akasaka - Allen TX, US
Martin Bouda - Plano TX, US
Takao Naito - Plano TX, US

Assignee:

Fujitsu Limited - Kawasaki

International Classification:

H04J 14/00

US Classification:

398 72, 398 63, 398 71

Abstract:

In accordance with the teachings of the present invention, a system and method for traffic distribution in an optical network is provided. In a particular embodiment, a traffic distribution module in a passive optical network (PON), includes a filter configured to receive downstream traffic in a first set of one or more wavelengths and a second set of one or more wavelengths from an optical line terminal (OLT), direct the traffic in the first set of wavelengths to a primary power splitter, and direct the traffic in the second set of wavelengths to a first connector. The traffic distribution module also includes a primary power splitter and a plurality of secondary power splitters. The primary power splitter is configured to receive the traffic in the first set of wavelengths and distribute the traffic in the first set to the plurality of secondary power splitters coupled to the primary power splitter such that optical network units (ONUs) in the PON receive the traffic in the first set of wavelengths. The traffic distribution module also includes a first connector configured to couple to a first module connector of a pluggable module and to forward the traffic in the second set of wavelengths to the pluggable module via the first module connector. The traffic distribution module also includes a plurality of second connectors configured to couple to a plurality of second module connectors of the pluggable module, receive the traffic in the second set of wavelengths from the pluggable module via the associated second module connectors, and forward the traffic in the second set to the plurality of secondary power splitters for distribution to particular ONUs in the PON.