WO1999035775A1 - Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance - Google Patents

Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance Download PDF

Info

Publication number
WO1999035775A1
WO1999035775A1 PCT/US1999/000367 US9900367W WO9935775A1 WO 1999035775 A1 WO1999035775 A1 WO 1999035775A1 US 9900367 W US9900367 W US 9900367W WO 9935775 A1 WO9935775 A1 WO 9935775A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical
multiplexer
signals
wavelength
signal
Prior art date
Application number
PCT/US1999/000367
Other languages
English (en)
Inventor
Xin Cheng
Shouhua Huang
Original Assignee
Osicom Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Osicom Technologies, Inc. filed Critical Osicom Technologies, Inc.
Priority to EP99902110A priority Critical patent/EP1050131A1/fr
Priority to AU22164/99A priority patent/AU2216499A/en
Publication of WO1999035775A1 publication Critical patent/WO1999035775A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/506—Multiwavelength transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/572—Wavelength control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/03—WDM arrangements
    • H04J14/0305—WDM arrangements in end terminals

Definitions

  • the invention relates to optical communication systems generally and, more particularly, to short distance optical communication systems which carry plural optical signals of different wavelengths simultaneously.
  • Optical communication systems are a substantial and rapidly growing component of communication networks.
  • Optical communication systems are any systems which use an optical signal to convey information across an optical waveguide medium (such as a fiberoptic cable or vacuum).
  • optical waveguide medium such as a fiberoptic cable or vacuum.
  • Such optical systems include telecommunications systems, cable television systems, and local area networks (LANs).
  • LANs local area networks
  • the majority of optical communications systems in current use are configured to carry an optical channel of a single wavelength over one or more optical waveguides.
  • time-division multiplexing use of a single optical channel (or fiberoptic strand) is rotated between various signal sources, with a portion of one signal transmitted, followed by a portion of another, in which complete signals are constructed from the portions of signals collected from each time slot. While this is a useful technique for carrying plural information sources on a single optical channel, its capacity is limited by the speed of electronic switching between time slots, limiting the maximum data transfer rate.
  • DWDM dense WDM
  • Prior art DWDM systems were designed for long distance applications, such as cross country fiberoptic cable systems.
  • optical wave dispersion is a particular problem due to the distances covered.
  • External modulation is more expensive and subject to breakdown than is direct modulation, but external modulation reduces wave dispersion over long distances.
  • an unmodulated laser beam is used as a carrier signal, and the specific data to be transmitted is added by a re-modulator.
  • the use of external modulation increases the cost and adds an additional component which may disable the system in the event of a breakdown.
  • external modulation has an inherent inefficiency requiring the use of a higher power laser than that used in direct modulation systems, further increasing the cost of the system, and reducing reliability due to the heat generated by such high powered lasers.
  • Prior art DWDM systems typically employ optical combiners and splitters as a means to combine and divide a signal over multiple paths. Such devices cause further attenuation. For this reason, as well as the attenuation resulting from signals traveling long distances over fiberoptic cables, DWDM systems have had to employ optical fiber amplifiers. In addition to their high cost, such amplifiers are unidirectional, that is, they can only pass signals in one direction. Obviously such systems are incapable of efficient bi-directional operation (i.e., a single fiberoptic strand cannot be used for sending information in both directions), a highly desirable characteristic if one is to fully utilize existing fiberoptic carriers. Some prior art WDM and DWDM systems have used a fiber grating or block grating to combine and/or split the signals.
  • WDM and DWDM systems cause signal loss resulting in the need for amplifiers, with their attendant problems, and are costly.
  • Another problem with prior art WDM and DWDM systems is that typically such systems are useable only in existing long distance telecommunications networks, in which the transmission speed and data format are known, and a clock-recovery circuit is used to recover and retime the high speed signals. Typically, this is immediately prior to the step of combining the signals in an optical combiner.
  • the clock-recovery circuit limits the system to transmitting data at a specified speed and according to a given format, usually the SONET transmission format.
  • optical communications systems adapted for short distance communication networks capable of handling data bi- directionally in numerous formats, that is expandable, can handle data at high transmission speeds, achieves this result at a minimal cost in terms of data loss, functionality, reliability and purchase and operational expense), and does not include extraneous components like amplifiers, external modulators, and clock recovery circuits.
  • the present invention provides an optical communication system capable of handling data bi-directionally in numerous formats, that is expandable, can handle data at high transmission speeds, and is cost efficient and reliable.
  • the present invention provides a bi-directional dense wavelength division multiplexing optical communications system capable of transmitting multiple signals over a single optical waveguide.
  • the system including a plurality of channelizers, for converting optical or electronic input signals from a sending station into an optical signal having a predetermined wavelength range, independent of the optical and electronic characteristics of the original transmission, with each channelizer converting signals into its own predetermined wavelength range; an optical waveguide; at least one wavelength multiplexer, which receives optical signals from the channelizers, combines them into a single combined optical signal and transmits same to the optical wave guide; and at least one wavelength demultiplexer, which receives the combined signals from the optical waveguide and isolates the individual respective modulated optical signals and transmits them to a receiving station, all without significant loss of signal strength.
  • the channelizer of the optical communications system also includes a photodetector, an electronic signal amplifier, a laser, and a laser driver, wherein each laser produces a modulated optical signal at a different respective and predetermined wavelength.
  • the wavelength multiplexers are capable of combining previously multiplexed signals from other wavelength multiplexers with signals from channelizers, and additional multiplexer's may be added without transmission interruption.
  • the wavelength multiplexers and wavelength demultiplexers are structurally identical and interchangeable with each other, allowing bi-directional operation, and said multiplexers/demultiplexers use at least one optical film filter for wavelength selection and isolation.
  • the channelizers are capable of converting both optical and electrical input signals into directly modulated optical signals having a respective predetermined wavelength range, and includes a directly modulated laser which produces the modulated optical signal.
  • the optical communication system includes at least five wavelength multiplexers, with the output ports of four of the five multiplexers feeding their combined signals to the fifth wavelength multiplexer, which in turn combines the combined signals and transfers the resultant combined signal to the optical waveguide.
  • FIG. 1 schematically depicts an optical communication system according to the present invention.
  • FIG. 2 schematically depicts a channelizer (18) used in the optical communication system of FIG. 1.
  • FIG. 3 schematically depicts a parallel cascade combination of multiplexer/demultiplexer sub units used in the optical communication system of FIG. 1.
  • FIG. 4 schematically depicts a serial cascade combination of multiplexer/demultiplexer sub units used in the optical communication system of FIG. 1.
  • FIG. 5 schematically depicts a serial/parallel hybrid cascade combination of multiplexer/demultiplexer sub units used in the optical communication system of FIG. 1.
  • FIG.6 schematically depicts an interference filter-based optical multiplexer and demultiplexer used in the optical communication system of FIG. 1.
  • FIG.7 schematically depicts an interference filter-based optical multiplexer used in the optical communication system of FIG. 1 , used in an alternative combination of multiplexer sub units.
  • FIG. 1 depicts the optical communications system 10 of the present invention.
  • the optical communications system 10 is interconnected to two or more transmission elements, such as transmission element 12, transmission element 14 and transmission element 16, which form the "input" of the system.
  • Each transmission element 14 transmits an information-bearing signal (not shown) from some outside source, such as a telecommunication system, LAN or cable television system, to the optical communications system 10 of the present invention.
  • Some transmission elements are adapted to transmit an electronic signal, while others are adapted to transmit an optical signal.
  • the optical communications system 10 of the present invention can accommodate a mixture of optical and electronic signals, as well as all the signals being optical or electronic.
  • Optical signals are typically generated by the user's terminal equipment, such as the SONET multiplexer, available from Alcatel, Lucent, Nortel, and NEC, or the FDDI network interface, available from Osicom.
  • Electronic signals are generally produced by a digital tape player or camera, such as the devices available from Sony, Hitachi, and Philips, or by fast network hubs and switches, such as those available from 3Com, Cisco, and Osicom.
  • the optical communications system 10 can accommodate any number of transmission elements, however in a preferred embodiment, sixteen (16) are employed. In FIG. 1 , the dotted line between transmission element 14 and transmission element 16 is to demonstrate that additional transmission elements can be accommodated.
  • the optical communications system 10 also includes a plurality of WDM wavelength channelizers, such as channelizer 18, channelizer 22 and channelizer 24, for receiving the transmitted information-bearing signal from the transmission element and transmitting an information- bearing optical signal at a predetermined wavelength.
  • a single channelizer such as channelizer 18, is interconnected with and receives an electronic or optical information-bearing signal from a single transmission element, such as transmission element 12. Referring to FIG.1 , the signal travels from the transmitting station 94
  • optical signals are passed out of the demultiplexer 98 and, if the original signal from the transmission element 12 was electronic, on to an optional receiver 122 which will convert the optical signals back to their original electronic form and format, and then to a receiving element 124. If the original signal from the transmission element 12 was optical, then it is transmitted directly from the demultiplexer 98 to the receiving element 124.
  • the receiving elements accepting optical signals are generally terminal equipment, such as SONET demultiplexer, available from Alcatel, Lucent, and Nortel, or FDDI network interface, available from Osicom.
  • FIG. 2 shows a channelizer 18 constructed according to the present invention.
  • the channelizer 18 has an electronic input 26 and an optical input 28, so as to accept both electronic and optical input.
  • Optical signals, from the optical input 28 are converted into an electronic signal by an electro-optical converter such as photo detector 32.
  • Photo detector 32 can comprise any number of commercially available electro-optical converter, such as those sold by Lucent, Epitaxx, Fujitsu, and Hewlett-Packard. That electronic signal is then amplified by a preamplifier and then a main amplifier, such as preamplifier 34 and main amplifier 36.
  • the resulting amplified information-bearing electronic signal is used to control a laser driver 38 (shown in FIG. 2 within broken lines). If the original information-bearing signal is an electronic signal, it passes through a signal conditioning circuit where it is filtered and amplified, and the resultant amplified information-bearing electronic signal is used to control the laser driver 38.
  • the laser driver 38 is commercially available and includes a modulator controller 46, a laser bias controller 48, a laser power monitor 52 and a laser modulator 54.
  • the laser modulator 54 modulates the current powering the laser 56 in accordance with the amplified information-bearing electronic signal.
  • the modulator controller 46 controls the magnitude of the variation in electrical current transmitted to the laser 56.
  • the laser bias controller 48 provides the required laser bias current.
  • An automatic temperature controller 62 which typically includes a temperature sensing device such as a thermister 64, and heating/cooling device, typically a thermoelectric cooler 66, is included to provide a stable operating temperature for the laser 56, thereby insuring greater precision in the operating wavelength of the optical output 58.
  • the laser 56 may be selected from a number of commercially lasers, and semiconductor lasers have been found to be particularly useful.
  • the laser 56 produces an optical signal at a predetermined channel wavelength, corresponding to multiplexer 68 and demultiplexer 98 channels (see FIGs. 1 and 3-6).
  • wavelengths emitted by channelizers are selected to be within the 1500 nanometer range, the range in which the minimum signal attenuation occurs for silica-based fibers.
  • the wavelengths can also be selected in 1300 nanometer range, the range in which the minimal signal dispersion occurs for the silica- based fibers. Other wavelength band may be also selected according to user requirements.
  • FIG. 1 shows a plurality of channelizers (18, 22 and 24) feeding their respective optical output (58a, 58b and 58d) into a single multiplexer 68. Showing a single multiplexer 68 in FIG. 1 is purely for drafting convenience. In a preferred embodiment, any number of multiplexers may be used. For instance, FIG. 3 shows four multiplexers, multiplexer 68, multiplexer 72, multiplexer 74 and multiplexer 76. Just as with the single multiplexer 68 in FIG. 1 , the four multiplexers in FIG.
  • optical output 58a can be processed by a single multiplexer 68.
  • FIG. 6 shows how multiplexer 68 combines plural information- bearing optical signals at selected wavelengths, such as optical output 58a, optical output 58b, optical output 58c and optical output 58d, onto a single waveguide, typically at a low loss.
  • Such an information-bearing signal at a DWDM wavelength from a channelizer, for example optical output 58a, is feed into a multiplexer input port 78a.
  • optical output 58b is fed into multiplexer input port 78b
  • optical output 58c is fed into multiplexer input port 78c
  • optical output 58d is fed into multiplexer input port 78d. All of these information-bearing optical signals are combined by the multiplexer 68 into a single information-bearing optical signal which is sent on a single optical waveguide, such as optical waveguide 82.
  • Optical waveguide 82 extends from the output port 80 of multiplexer 68.
  • the optical waveguide 82 is typically a single mode optical fiber, and is the principle transmission medium.
  • the optical waveguide 82 is the link between "sender" and "receiver.”
  • any number of multiplexers e.g., multiplexer 68, multiplexer 72, multiplexer 74 and multiplexer 76 may form the inputs to another multiplexer 84. This is also shown in FIG.
  • multiplexer 84 is receiving optical waveguide 82 from multiplexer 68 at multiplexer input port 78a; optical waveguide 86 from multiplexer 72; optical waveguide 88 from multiplexer 74 and optical waveguide 92 from multiplexer 76.
  • a multiplexer is not limited to receiving either all optical waveguides from multiplexers or all optical outputs from channelizers; the user is free to "mix and match.” For example, the user could alter the configurations shown in FIGs.
  • multiplexer input port 78a of multiplexer 84 to receive optical output 58a from channelizer 18 (FIG.2), while using the remaining input ports (e.g., multiplexer input ports 78b-d) for optical waveguide 86, optical waveguide 88, and optical waive guide 92 (FIG. 3), from other multiplexers.
  • the combinations are limitless.
  • Optical waveguide 82 extends from multiplexer 68 at one end of the optical waveguide 82 and from demultiplexer 98 at its other end.
  • the demultiplexer 98 is structurally identical to the multiplexer 68.
  • FIG. 6 shows multiplexer 68 and a demultiplexer 98.
  • Multiplexer 68 has a plurality of reflectors, one for each multiplexer input port, such as reflector 102, reflector 104, reflector 106 and reflector 108.
  • Each reflector is coated with a wavelength- selective dielectric thin-film filter. These consist of high and low refractive index dielectric films in alternating layers, which pass information-bearing optical signals of a predetermined wavelength, but reflect all other wavelengths. By changing composition of the dielectric films, the desired wavelength can be selected.
  • optical output 58a has been transmitted by channelizer 18 (FIG. 1 ) at the predetermined wavelength noted in FIG. 3 as ⁇ 1.
  • the dielectric filter of reflector 102 is thus designed to pass only optical signals at wavelength ⁇ 1.
  • optical output 58a is only at wavelength ⁇ 1.
  • any errant optical signal at some other wavelength would not pass into multiplexer 68, providing an extra assurance of signal quality.
  • Optical output 58a is thus passed through reflector 102, and to the interior side of reflector 104.
  • reflector 104 will only pass an optical signal at wavelength ⁇ 2 from optical output 58b, which is joined with the signal from optical output 58a and passed to the interior side of reflector 106. The process repeats itself until all incoming optical signals are joined (in this example, ⁇ 1 , ⁇ 2, ⁇ 3 and ⁇ 4) onto optical waveguide 82. Viewing FIG.
  • optical waveguide 82 transmits the joined optical signals to demultiplexer 98, entering at input port 110 which is an exact duplicate of output port 80 of multiplexer 68.
  • Reflector 112 just like reflector 102 of multiplexer 68, is adapted to allow only optical signals of wavelength ⁇ 1 to pass (which are passed out of the demultiplexer 98 and to an optional receiver 122 which will covert the optical signals back to their original form and format, and then to a receiving element 124), and to reflect all other wavelengths.
  • Reflector 102 of the multiplexer 68 such reflection is in the interior side of reflector 112, and such signals (at wavelengths ⁇ 2, ⁇ 3 and ⁇ 1 ) are reflected to reflector 114.
  • Reflector 114 similarly, will pass only signals at wavelength ⁇ 2, and reflect to reflector 116 the remaining wavelengths (A3 and ⁇ 4). As can be seen, this process repeats itself any number of times for any number of wavelengths.
  • FIGs. 3-5 show three such configurations: parallel cascade (FIG. 3), serial cascade (FIG. 4), and hybrid cascade (FIG. 5).
  • FIG. 3 output ports of plural sub units of multiplexer (68, 72, multiplexer 74 and 76), as a group of information-bearing optical signals from a group of channelizers are fed into input ports of multiplexer 84. That combination of signals forms a multiplexed optical signal which is output to optical waveguide 126.
  • output ports of plural sub units of multiplexers (72, 74 and 76) are connected serially to multiplexer 68, which outputs the combined signal to optical waveguide 82.
  • the output port of multiplexer 68 is connected to an input port of multiplexer 72
  • the output port of multiplexer 76 is connected to an input port of multiplexer 74.
  • Outputs of multiplexer 72 and multiplexer 74 are fed into multiplexer 84 which in turn combines all channels onto optical waveguide 126.
  • FIG. 3 shows demultiplexer 98, demultiplexer 128, demultiplexer 132, demultiplexer 134 and demultiplexer 136 in parallel cascade
  • FIG. 4 shows the same demultiplexers in serial cascade
  • FIG. 5 shows them in a hybrid cascade configuration.
  • FIGs. 3-5 all show multiplexers in the same configuration as demultiplexers, users are free to mix configurations.
  • a user could arrange multiplexers in a hybrid cascade configuration and demultiplexers in parallel cascade. Other combinations are limited only by the inventiveness of the user.
  • demultiplexer 1208 demultiplexer 132, demultiplexer 134 and demultiplexer 136 (FIGs. 3-5) then these demultiplexers act as multiplexers, and similarly multiplexer 68, multiplexer 72, multiplexer 74 and multiplexer 76 function as demultiplexers.
  • a further advantage of the optical communications system 10 of the present invention is a modularity of the multiplexers and demultiplexers.
  • usage changes such that for example, multiplexer 68 and demultiplexer 128 are no longer necessary, or require servicing or repair, they can be removed without disruption to the rest of the system.
  • additional multiplexer(s) can be added in any number of ways, such as attaching the optical waveguide from an additional multiplexer to the multiplexer input ports, such as multiplexer input port 78a of multiplexer 68 (FIG. 3).
  • Corresponding demultiplexers can be added (also not shown).

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

L'invention concerne un système de communication optique à haute capacité extensible et rentable utilisant un multiplexage en longueur d'onde. Des multiplexeurs et des démultiplexeurs modulaires à faible perte sont utilisés pour augmenter la flexibilité du système et réduire la perte d'insertion générale du système.
PCT/US1999/000367 1998-01-09 1999-01-07 Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance WO1999035775A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP99902110A EP1050131A1 (fr) 1998-01-09 1999-01-07 Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance
AU22164/99A AU2216499A (en) 1998-01-09 1999-01-07 Short distance dense wavelength division multiplexing optical communication system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US494898A 1998-01-09 1998-01-09
US09/004,948 1998-01-09

Publications (1)

Publication Number Publication Date
WO1999035775A1 true WO1999035775A1 (fr) 1999-07-15

Family

ID=21713349

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1999/000367 WO1999035775A1 (fr) 1998-01-09 1999-01-07 Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance

Country Status (4)

Country Link
EP (1) EP1050131A1 (fr)
AU (1) AU2216499A (fr)
TW (1) TW425789B (fr)
WO (1) WO1999035775A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1185017A1 (fr) * 2000-08-30 2002-03-06 Telefonaktiebolaget Lm Ericsson Réseau de communication optique
US6519384B2 (en) 2000-08-30 2003-02-11 Telefonaktiebolaget Lm Ericsson (Publ) Optical communication network

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0444348A2 (fr) * 1990-02-28 1991-09-04 AT&T Corp. Système optimalisé de communication optique par multi-plexage à longueur d'onde
DE4302133A1 (de) * 1993-01-27 1994-07-28 Kabelmetal Electro Gmbh Multiplexer/Demultiplexer für drei Wellenlängen
US5504609A (en) * 1995-05-11 1996-04-02 Ciena Corporation WDM optical communication system with remodulators
EP0758169A2 (fr) * 1995-08-09 1997-02-12 Nec Corporation Système et méthode de transmission à multiplexage d'ondes
JPH09233053A (ja) * 1995-12-22 1997-09-05 Furukawa Electric Co Ltd:The 光信号伝送方法
WO1997049248A1 (fr) * 1996-06-21 1997-12-24 Fiber Optic Network Systems Corp. Systeme de multiplexage par repartition en longueur d'onde

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0444348A2 (fr) * 1990-02-28 1991-09-04 AT&T Corp. Système optimalisé de communication optique par multi-plexage à longueur d'onde
DE4302133A1 (de) * 1993-01-27 1994-07-28 Kabelmetal Electro Gmbh Multiplexer/Demultiplexer für drei Wellenlängen
US5504609A (en) * 1995-05-11 1996-04-02 Ciena Corporation WDM optical communication system with remodulators
EP0758169A2 (fr) * 1995-08-09 1997-02-12 Nec Corporation Système et méthode de transmission à multiplexage d'ondes
JPH09233053A (ja) * 1995-12-22 1997-09-05 Furukawa Electric Co Ltd:The 光信号伝送方法
WO1997049248A1 (fr) * 1996-06-21 1997-12-24 Fiber Optic Network Systems Corp. Systeme de multiplexage par repartition en longueur d'onde

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 098, no. 001 30 January 1998 (1998-01-30) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1185017A1 (fr) * 2000-08-30 2002-03-06 Telefonaktiebolaget Lm Ericsson Réseau de communication optique
US6519384B2 (en) 2000-08-30 2003-02-11 Telefonaktiebolaget Lm Ericsson (Publ) Optical communication network

Also Published As

Publication number Publication date
EP1050131A1 (fr) 2000-11-08
AU2216499A (en) 1999-07-26
TW425789B (en) 2001-03-11

Similar Documents

Publication Publication Date Title
EP0896448B1 (fr) Système de noeud optique pour architecture en anneau et procédé correspondant
US5712932A (en) Dynamically reconfigurable WDM optical communication systems with optical routing systems
US7433594B2 (en) Node apparatus, optical wavelength division multiplexing network, and system switching method
US6459516B1 (en) Dense WDM add/drop multiplexer
JP2888272B2 (ja) 光ネットワークおよび中継ノード
JP3772594B2 (ja) 光ネットワーク中継装置
US6597482B1 (en) Multiplexing/demultiplexing apparatus for wavelength division multiplexed system and wavelength division multiplexed passive optical subscriber networks using the same apparatus
US20120087658A1 (en) Wavelength Selective Switch Band Aggregator and Band Deaggregator and Systems and Methods Using Same
US6661973B1 (en) Optical transmission systems, apparatuses, and methods
JP2001103009A (ja) 通信システム
EP1715610B1 (fr) Procédé et dispositif permettant d'augmenter le nombre de canaux d'information transportés par des guides d'ondes optiques
US6400478B1 (en) Wavelength-division-multiplexed optical transmission system with expanded bidirectional transmission capacity over a single fiber
US6348985B1 (en) Bidirectional WDM optical communication network with data bridging plural optical channels between bidirectional optical waveguides
US6243175B1 (en) WDM optical communication system having reduced loss and cross-talk
US4957339A (en) Optical communication system, particularly in the subscriber area
US6198556B1 (en) WDM ring transmission system
WO1999012268A2 (fr) Procede et systeme de multiplexage modulaire et d'amplification dans un plan multicanal
US20010048799A1 (en) Optical communication system
US8195048B2 (en) Optical transport system architecture for remote terminal connectivity
US7457543B2 (en) Add/drop module for single fiber wavelength division multiplexing systems
WO1999035775A1 (fr) Systeme de communication optique par multiplexage en longueur d'onde renforcee a courte distance
US20050129403A1 (en) Method and system for communicating optical traffic at a node
US10735126B1 (en) Splitter-based colorless-directionless-contentionless reconfigurable optical add/drop multiplexer
US7609970B2 (en) Add/drop node for an optical communications network
WO2002087127A9 (fr) Systeme optique a multiplexage par repartition approximative en longueur d'onde (cwdm)

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG UZ VN YU ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
NENP Non-entry into the national phase

Ref country code: KR

WWE Wipo information: entry into national phase

Ref document number: 1999902110

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1999902110

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWW Wipo information: withdrawn in national office

Ref document number: 1999902110

Country of ref document: EP