Kokusai Denshin Denwa Kabushiki Kaisha

Other

Kokusai Denshin Denwa Co., Ltd.

Kdd Corporation

Kdd Submarine Cable Systems, Inc.

Mitsubishi Denki Kabushiki Kaisha

Shin-etsu Chemical Co., Ltd.

Kddi Corporation

Kddi Submarine Cable Systems Inc.

Kokusai Benshin Kabushiki Kaisha

Noboru Edagawa

Shu Yamamoto

Masatoshi Suzuki

Hidenori Taga

Shigeyuki Akiba

Itsuro Morita

Keiji Tanaka

Hiroharu Wakabayashi

Tetsuya Miyazaki

Kiyofumi Mochizuki

Takehiro Tsuritani

Kiwami Matsushita

Noriyuki Takeda

Yoshihiro Yoshida

Hideaki Tanaka

Yukio Horiuchi

Kazuo Koya

Tadayoshi Kitayama

Yoshinao Iwamoto

Takashi Mizuochi

Katsuhiro Shimizu

Aritomo Uemura

Takayuki Miyakawa

Minoru Taya

Takeshi Komiya

Yuichi Matsushima

Tadakatsu Shimada

Koji Goto

Shinichi Nakagawa

Kuniaki Motoshima

Shiro Ryu

Tomohiro Otani

Yuichi Yamada

Katsumi Takano

Tetsuyuki Miyakawa

Tadakatsi Shimada

The invention is applied to a PON system including an optical line terminal (OLT) at a center station, a plurality of optical network units (ONUs) at subscribers' sites, and an optical transmission line shared by the plurality ONUs to optically connect between the OLT and the plurality of ONUs. Each of the ONUs requests the OLT to assign a logical link according to start-up of an application.

Method for dynamically establishing logical link in PON systems and an optical network unit for the method

To inform a location of a caller to the other party in an IP phone system, a wireless IC tag preserving unique ID information is attached to an optical connector of a user connection port. The relations between locations of the optical connectors and ID information of corresponding wireless IC tags are stored in a port control database. An IC tag reader in an optical network unit (ONU) reads the ID information in the wireless IC tag attached to the optical connector to which the ONU is connected. When an emergency call is initialed, the ONU transmits destination information of the emergency call and the ID information of the wireless IC tag to a central station. A control terminal in the central station compares the ID information of the wireless IC tag against the port control database to determine a location of the optical connector. The central station adds the determined location information to the destination information of the emergency call and transmits the information to an IP network.

Method to provide caller's location in IP phone system, optical transmission system, optical connector, and optical network unit

The optical amplifier according to the present invention is constructed such that the amount of the electric current fed to the power feeding lineis first detected by the current detection means, and then a setting signal is generated to each of the bypass circuitsandin accordance with the thus detected amount of the fed current, and thereafter the output level of each of the optical repeater circuitsandis controlled respectively by the bypass circuitsand, so that the output level of these repeater circuitsandcan be controlled in accordance with the amount of the current fed to the power feeding line

Optical amplifier having various control circuitry

An optical TDM multiplexing apparatus to multiplex a plurality of input signals in the optical stage in the time domain according to the invention comprise a plurality of signal light sources to generate optical signals each having a wavelength different from the others to carry each of the plurality of the input signals, a timing adjuster to adjust timings between the respective optical signals so that each optical signal output from the plurality of the signal light sources is disposed on a time slot different from the others in the time domain, an optical multiplexer to multiplex each optical signal output from the timing adjuster in the wavelength domain and a wavelength converter to convert each wavelength of the output light from the optical multiplexer into a predetermined wavelength.

Optical TDM multiplexer, optical TDM demultiplexer, WDM/TDM converter and TDM/WDM converter

An optical transmitter outputs WDM signal lights comprising signal lights with 100 wavelengths of 10 Gbit/s, onto an optical transmission fiber. In the optical transmission line, a transmission fiber and a local area dispersion compensation fiber are disposed per repeater span defined by an optical amplification repeater, the local area dispersion compensation fiber is for compensating the average chromatic dispersion in the repeater span to become 2 ps/nm/km as well as a dispersion slope to become zero, and a wide area dispersion compensation fiber for compensating the average chromatic dispersion to become &minus;0.2 ps/nm/km as well as the dispersion slope to become zero is disposed per predetermined number of optical repeater spans. The optical transmission fiber comprises a single mode optical fiber with large core diameter having a zero dispersion wavelength at a 1.3 &mgr;m band and plus chromatic dispersion at a signal wavelength band (a 1.55 &mgr;m band). The optical amplification repeater comprises an erbium-doped optical fiber to be pumped by a 0.98 &mgr;m band pumping light.

Optical transmission system, optical transmission line and optical transmitter

An optical fiber transmission line for realizing satisfactory long haul transmission characteristics using two kinds of optical fibers. The optical fiber transmission line includes a plurality of local dispersion compensating spans, wide dispersion compensating spans disposed at predetermined intervals, and optical repeating amplifiers to connect each span. The local dispersion compensating span includes a first optical fiber with positive dispersion having an effective core area of 130 &mgr;m or more and a second optical fiber with a negative dispersion value of &minus;50 ps/nm/km or less to transmit the light output from the first optical fiber. The wide dispersion compensating span consists of a third optical fiber having the same configuration and composition with the first optical fiber.

Optical fiber transmission line

An optical fiber ( ) with a large effective core area and a large chromatic dispersion value is disposed on an input side of signal light, and an optical fiber ( ) with a small effective core area and a small chromatic dispersion value or a chromatic dispersion value of negative polarity is disposed on an output side of the signal light. A pumping light source ( ) generates pumping light of 1450 nm to cause Raman amplification of 1550 nm in the optical fiber ( ). The output light from the pumping light source ( ) enters the optical fiber ( ) from the back through a WDM optical coupler ( ). Provided that y&equals;(Pin&minus;&agr;)/(Pp&middot;10 Log L) where input power of the optical fiber ( ) (i.e. output power of an optical transmitter ( )) is Pin, a total loss of the optical fibers ( and ) is &agr;, pumping power for Raman amplification is Pp, and a total length of the optical fibers ( and ) is L, the relation between ratio x (0&lE;x&lE;1) of the optical fiber ( ) and y is expressed as y&equals;6.63&times;10 x&minus;0.077. Here, the satisfactory x value is in a range from &plus;0.2 to &minus;0.2 of the y value.

Optical transmission line

An object of this invention is to improve transmission characteristics in WDM transmission. An optical transmitter ( ) wavelength-multiplexes signal lights of wavelengths &lgr; through &lgr;n and outputs them onto an optical transmission line ( ). Optical powers of the signal lights of the respective wavelength through &lgr;n are identical or become smaller proportional to the wavelength. One repeater span of the optical transmission line ( ) is composed of an optical fibers ( ) and an optical amplifier ( ), and a gain equalizer ( ) is dispersed every several repeater spans. The optical amplifier ( ) in the repeater span amplifies each signal light so that optical power of a signal on the shorter wavelength side becomes smaller than that of a signal on the longer wavelength side. The gain equalizer ( ) equalizes optical powers of the respective signal lights.

Optical transmission system, its method, and optical amplification transmission line

An object of the present invention is to realize almost the same transmission characteristic in all wavelengths at a transmission rate of 10 Gb/s or more. An optical transmitter outputs WDM signal light multiplexed with signal light of a plurality of wavelengths toward an optical transmission line . The optical transmission line comprises an optical transmission fiber , an optical repeating amplifier and a dispersion compensating fiber . The gain characteristic of the optical repeating amplifier is set so that the gain becomes the maximum at the effective zero dispersion wavelength of the optical transmission line and that lowers inversely proportional to the distance from the effective zero dispersion wavelength. The whole optical transmission line is set so that the peak power deviation between the effective zero dispersion wavelength &lgr;0 and the wavelength &lgr;1 or &lgr;n on both end becomes approximately 4 dB.

WDM optical transmission system and an optical transmission line thereof

An object of the present invention is to prevent an increase of the degree of polarization of an output pumping light even if one of pumping light sources has a failure. Laser diodes ( ) are composed of FP-LDs made of InGaAsP to laser-oscillate at 1480 nm band. The outputs from the laser diodes ( ) enter a polarizing beam splitter ( ) in orthogonal state of polarization and are combined there. The combined light by the polarizing beam splitter ( ) enters a depolarizing element ( ) and is depolarized there.

Pumping light generator and fiber Raman amplifier

The optical amplifier according to the present invention is constructed such that the amount of the electric current fed to the power feeding line is first detected by the current detection means, and then a setting signal is generated to each of the bypass circuits and in accordance with the thus detected amount of the fed current, and thereafter the output level of each of the optical repeater circuits and is controlled respectively by the bypass circuits and , so that the output level of these repeater circuits and can be controlled in accordance with the amount of the current fed to the power feeding line

A dispersion compensating optical transmission line comprises a plurality of optical transmission fibers for transmitting signal light, at least one first dispersion compensator disposed at a first dispersion compensating cycle for compensating an accumulated chromatic dispersion of the signal light so that an average chromatic dispersion is equal to a first desired value, and a plurality of second dispersion compensators disposed at a second dispersion compensating cycle shorter than the first dispersion compensating cycle for compensating the accumulated chromatic dispersion of the signal light so that an average chromatic dispersion is equal to a second desired value which absolute value is larger than that of the first desired value.

Dispersion compensating optical transmission line and system

The soliton pulse compression optical fiber comprises a core and a clad that surrounds the core for compressing the injected light pulse in width. The maximum relative index difference between the core and the clad is between about 1.2% and 2.5%. The core diameter of the soliton pulse compression optical fiber varies along the length of the soliton pulse compression optical fiber and the core has a step-like refractive index distribution. The optical fiber perform of the soliton pulse compression optical fiber comprises a core preform, which is to be a core of the soliton pulse compression optical fiber, and a clad preform that surrounds the core preform. The maximum relative index difference between the core perform and the clad preform is also between about 1.2% and 2.5%.

Soliton pulse compression optical fiber and method for making soliton pulse compression optical fiber

An optical digital regenerator for digitally regenerating an input signal in an intact optical state. A first operating unit has a first probe light generator for generating a first probe light and a first optical operator for converting a waveform of the first probe light output from a first probe light generator according to an optical intensity waveform of the input signal light. A clock extractor extracts a clock component of the input signal light from a photocurrent generated by the first optical operator. A second optical operating unit has a second probe light generator for generating a second probe light pulsed in accordance with the clock output from the clock extractor and a second optical operator for sampling the second probe pulse light output from the second probe light generator.

Optical digital regenerator

The object of this invention is to improve SNR in the Raman amplification. An optical fiber ( ) consists of a dispersion shift fiber in which a zero dispersion wavelength is shifted to the 1.55 &mgr;m band, and an optical fiber ( ) consists of a single mode optical fiber having the effective core area of 100 &mgr;m which is larger than that of the optical fiber ( ). An optical coupler is disposed at the optical signal emission end of the optical fiber ( ). A laser diode ( ) outputs the laser light of 1455 nm as a Raman pumping light source. The output light from the laser diode ( ) is introduced into the optical fiber ( ) from the back, namely in the opposite direction to that of the optical signal propagation. The ratio of the Raman gain coefficient of the optical fiber ( ) to that of the optical fiber ( ) should be 1/1.08 or less, preferably 1/1.1 or less.

Raman amplifier

Growing community of inventors

Tokyo, Japan

Noboru Edagawa