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WO2000064078A1 - Procede et dispositif permettant la realisation d'un brasseur optique - Google Patents

Procede et dispositif permettant la realisation d'un brasseur optique Download PDF

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Publication number
WO2000064078A1
WO2000064078A1 PCT/FI2000/000226 FI0000226W WO0064078A1 WO 2000064078 A1 WO2000064078 A1 WO 2000064078A1 FI 0000226 W FI0000226 W FI 0000226W WO 0064078 A1 WO0064078 A1 WO 0064078A1
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WO
WIPO (PCT)
Prior art keywords
optical
signal
output
input
cross
Prior art date
Application number
PCT/FI2000/000226
Other languages
English (en)
Inventor
Markku Oksanen
Original Assignee
Nokia Networks Oy
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 Nokia Networks Oy filed Critical Nokia Networks Oy
Priority to AU35599/00A priority Critical patent/AU3559900A/en
Publication of WO2000064078A1 publication Critical patent/WO2000064078A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0228—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths
    • H04J14/023—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths in WDM passive optical networks [WDM-PON]
    • H04J14/0232—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths in WDM passive optical networks [WDM-PON] for downstream transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0228—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths
    • H04J14/023—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths in WDM passive optical networks [WDM-PON]
    • H04J14/0235—Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths in WDM passive optical networks [WDM-PON] for upstream transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0278—WDM optical network architectures
    • H04J14/0282—WDM tree architectures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0009—Construction using wavelength filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0011—Construction using wavelength conversion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0015—Construction using splitting combining
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0037—Operation
    • H04Q2011/0039—Electrical control

Definitions

  • the invention relates generally to optical transmission systems using WDM, Wavelength Division Multiplexing, and especially to an optical cross-connection for implementation in such a system.
  • the data flow to be transmitted is used for modulating an optical signal, and the modulated optical signal is supplied to an optical fibre.
  • the capacity of the transmission system can be increased in two different ways: by increasing the band width of the data flow or by increasing the number of wavelengths transported in the fibre. The latter alternative is efficiently implemented by WDM, Wavelength Division Multiplexing.
  • WDM Wavelength Division Multiplexing
  • a 1550 nm window is a typical wavelength range for optical data transmission.
  • the light to be transmitted is coherent light, that is, the light signal to be transmitted contains only a certain frequency spectrum of a regular shape.
  • Major characteristics of the components of the optical fibre's output end are related not only to optical power but also to the width of the resulting spectrum and to the degree of modulation of the signal to be transmitted.
  • the quality and structure of components that can be used depend on the purpose of use. Lasers and filters functioning at an exact optical wavelength are essential components in wavelength division multiplexing.
  • the window to be used determines what kind of laser is the most suitable in the system to be implemented.
  • an optical transmitter usually a laser suitable for the purpose, to generate a coherent light signal.
  • an optical receiver e.g. an APD, avalanche photo diode, or a PIN diode, which is simpler than the one mentioned above.
  • Broadcast and select architecture is a part of the WDM network architecture. The above-mentioned architecture is described with the aid of a simple diagrammatic plan in Figure 1.
  • A, B and C illustrate network nodes, which transmit signals at different wavelengths: node A transmits at wavelength ⁇ 1 f node B at wavelength ⁇ 2 and node C at wave- length ⁇ 3 .
  • an optical combiner (the figure shows a star combiner, but it could also be a bus com- biner), the duty of which is to collect signals transmitted by the nodes and to broadcast them further to all nodes in the network.
  • Each node has an optical transmitter and an optical receiver. With the aid of an adjustable filter element at the receiving end the node can select the wavelength it desires from the arriving signal. Transmitters and receivers operate at the same speed.
  • the broadcast and select network does not route signals, but it sends further to all nodes in the network the signals it receives from the nodes. It is a problem with the system presented above that it is not able to distinguish from each other two signals arriving at the same wavelength. For example, if node C, too, transmits a signal at wavelength ⁇ .,, then the wavelengths of nodes A and C will overlap. In addition, a great many wavelengths are transmitted unnecessarily in the system, since the receiving end does not usually make use of all wavelengths that are transmitted to it.
  • Known structures of the optical cross-connection are based on a cross-connection function in an optical space switch, wherein incoming wavelengths are switched over to outgoing fibres. It is also known to implement a cross-connection by an opto-elect c-opto converter located between the inlet and the exit. Problems with known cross-connection implementations are e.g. the small number of channels and also the circumstance that two (or more) same wavelengths can not be placed in the same fibre without a wavelength conversion, because the same wavelengths will otherwise be superimposed. The wavelength conversion is generally implemented by using a transponder converting the wavelength. It is difficult to implement an electric cross-connection matrix having a high penetration capacity.
  • Another problem as yet unsolved is how to implement such a cross-connection, which would broadcast the wavelengths of the WDM signal from the incoming fibre and would later rearrange them on the selected outgoing optical fibres.
  • a possible solution could be e.g. a pure switch solution, but it is extremely difficult to implement one, because the switch ought to be able to deal with hundreds of signals. Even dealing with e.g. 256 signals would be difficult, if it must be possible freely to select a certain signal from them and lead it out of a certain gate. In fact, one of the greatest problem of the solution would be the rearrangement of wavelengths.
  • the invention concerns an optical cross-connection, which is intended for use in an optical telecommunications system based on WDM technology, especially in a network node of a telecommunications system.
  • the objective of the invention is to implement a very high-capacity cross- connection architecture by utilising a coherent optical transmission layer and broadcast and select architecture. The established objective is achieved in the manner presented in the independent claims.
  • the invention aims at implementing a cross-connection apparatus with a high packing density, that is, the objective is to maximise the data transmission capacity of the cross-connection system.
  • opto-electric-opto converters are placed both at the input end and the output end of the cross-connection area and, in addition, narrow-band modulation is utilised, with the aid of which wavelengths arriving in the device are converted into wavelengths inside the apparatus.
  • the signal brought into the cross-connection apparatus is modulated in a single- sideband modulator SSB allowing narrowing of the band of the optical signal. Thanks to the single-sideband emission, the signals can be packed very close to each other, whereby 2 - 10 times more wavelengths can be placed within the same wavelength range compared with earlier cross-connection solutions.
  • the cross- connection method in accordance with the invention is very flexible; within the optical cross-connection area the cross-connection is not restricted to any certain wavelength range, but it may be based also on free-space optics, besides fibre optics.
  • the solution according to the invention can thus be applied e.g. in a wavelength range of visible light, besides the so-called telecom wavelengths generally used in optical telecommunications.
  • Figure 1 illustrates the principle of the known broadcast and select architecture in a WDM network
  • Figure 2 shows an embodiment of cross-connection architecture in accordance with the invention.
  • the cross-connection implementation includes several optical incoming fibres (11 IN) and the optical signals arriving from these are conducted to input gates of the cross- connection apparatus.
  • the input gates include elements for converting the signal from an optical into an electric form (A,), components for forming an optical carrier wave (C,), and components for modulating the carrier wave by a useful signal (B,). From the input gates the different signals, of which there may be hundreds or even thousands, are conducted to an entirely optical broadcast and select cross-connection area, wherein the signals are combined (D) and from which the said signals are broadcast further (E) to several output gates.
  • the output gates include components for detecting the signal and for converting the optical signal into electric form (F,), as well as compo- nents for converting the signal from electric into optical form (H,).
  • F, electric form
  • H compo- nents for converting the signal from electric into optical form
  • a typical practical example could be a system, wherein the signals are within a wavelength range of 1530 -1560 nm.
  • the wavelengths arriving in the device need not necessarily be different, but e.g. several different signals may arrive at the same wavelength, because the signals are converted onto wavelengths of their own inside the device, whereby they can be distinguished from each other on the output side.
  • optical signals containing several different wavelengths arrive along the optical fibres (11 ,..., IN) shown at the left in the figure to the cross-connection device, so that there is only one separate optical signal at one input gate.
  • gate 1 there could be e.g. wavelength 1530.334 nm (195.9 THz) and at the following gates wavelengths at intervals of approximately 0.8 nm (100 GHz) up and all the way to 1563.863 nm.
  • the cross-connection apparatus in the example would allow connecting of 43 different wavelengths from the input gates to the output gates.
  • the num- ber of different channels would be 85.
  • Each optical fibre arriving at the input gate is connected functionally to its own optical-to-electric converter A réelle wherein the incoming signal is detected and converted into a broadband electric signal.
  • 2-R- or 3-R regeneration is carried out for the signal.
  • 2-R regeneration is a technique carried out for digital data, wherein the data is strengthened and reshaped, whereas in 3-R regeneration the data is strengthened, reshaped and timed.
  • This layer may be an entirely broadband one, especially when linear modulation signals, such as e.g. CA - or Cellular RF signals are concerned.
  • Each optical signal which has been converted into electric form is conducted into an optical single- sideband modulator SSB, which is indicated by B, in the figure.
  • a new optical carrier wave OC depart is also conducted into the modulator, which carrier is obtained from laser C, operating exactly at a certain wavelength.
  • Each laser C may function at a certain wavelength of its own and the lasers may be e.g. of the Heterodyne Injection Locked Laser type.
  • the interval between carrier wave frequencies is preferably equal to the double bandwidth of each electric broadband signal.
  • single-sideband modulator B a digital amplitude modulation is performed on the carrier wave.
  • single-sideband modulator SSB the band of the optical signal can be narrowed and the signals can be packed very close to each other, whereby 2 - 10 times more wavelengths can be placed in the same optical spectrum than in conventional cross- connection solutions.
  • optical combiner D may be e.g. a combiner combining the incoming optical signals. In this example, the average power of signals is 1 mW. There may be hundreds of signals at the same time, even thousands of signals. From combiner D the signals are conducted to optical divider E, to which the combiner is functionally connected by way of an optical transmission path. Combiner D and divider E together form a broadcast component.
  • the said devices may be separate as in this example, but such an embodiment where one device contains the functionality of combiner D and divider E is also possible.
  • Optical divider E once again sepa- rates the signals combined by combiner D. If there are e.g. 1000 channels in the embodiment, the signal power is hereby 1 mW at each output gate.
  • Important advantages are achieved when dealing with sideband signals only: firstly, so-called telecom wavelengths are not processed directly, but since all incoming wavelengths will undergo wavelength conversion, it is possible within the said entirely optical area to process wavelengths within any wavelength range which can be freely selected. With the system according to the invention it is possible to process thousands of wavelengths, which is not possible with the present systems based on switch matrices.
  • Detector F is a so-called heterodyne receiver.
  • Each detector F 'sees' all signals in divider E, in other words, all signals are visible in one medium, which in the embodiment can be either a device, a wire, an optical fibre or an optical route. It is hereby possible that e.g. three different receivers F, can receive the same signal and transmit it further, if they so desire. The same signal can thus be distributed to several different places, but some signals are not necessarily transmitted further.
  • a set of lasers on the in- put gate side there is a set of lasers on the in- put gate side, and with the aid of a local oscillator signal G available from the input side the desired wavelength is selected for a certain detector F, In other words, detector F, may select the desired wavelength from any laser C,.
  • detector F there is the said set of lasers on the input gate side, and in addition there is also a set of lasers on the output gate side, which may be implemented either as a separate set of lasers or in such a way that each heterodyne detector F, contains its own adjustable laser C,' . With the aid of an adjustable laser and by adjusting the wavelength it is possible to select the correct channel very precisely.
  • heterodyne detector F the optical signal is converted into electric form. From component F, the signals go out arranged in electric form, so that e.g. a signal arrived in the system from input gate 11 is got out from the output gate of component F 46 .
  • the output gate of detector F is functionally connected to the input gate of component H,.
  • H is e.g. a modulator transponder, which with the aid of an electric broadband signal modulates from the outgoing optical wavelength.
  • Low-pass filters FC may be installed on the transmission path between the said components F, and H, in the manner shown by the figure.
  • the output gates (01 ON) of the above-mentioned components H are output for the entire cross-connection apparatus, from which output gates the desired optical signal can be transmitted at any wavelength used in optical telecommunications.
  • the cross-connection according to the invention can be implemented e.g. in the telecommunications node of a WDM network.
  • the bit flow is processed at wavelength level, that is, each bit flow is rearranged and routed at the wavelength level.
  • An important advantage achieved with the solution according to the invention is that the rearrangement of signals does not necessarily take place at typical wavelengths used in telecommunications; in the optical area of the cross-connection embodiment shown in the middle of the figure the optics may function at any wavelength, that is, it need not be fibre optics at all, but the implementation may be with any optical system, e.g. with so-called free space optics.
  • the number of signals to be cross-connected may vary greatly. This advantage, too, is achieved by using single-sideband signals.
  • the wave range used may also be another than the 1550 nm window mentioned in the example, e.g. a 1300 nm or 1700 nm or any other range, wherein optical sources may be used.
  • the drawings used and their related explanation are only intended to illustrate the inventive idea. Different variations are of course possible in the practical implementation. There are quite many different implementation alternatives.
  • the laser set according to the example can be implemented in very many different ways; firstly, separate lasers are not necessarily needed, but any way of producing such comb wavelengths can be used, from which suitable wavelengths can be selected.
  • the lasers may be of any kind, e.g. semiconductor lasers or solid-state lasers.
  • the components to be used are selected individually for the application, in other words, the invention is not limited to the use of certain lasers, since the use of free-space optics demands its own special ar- rangements.
  • the most important matter for the invention is the maximising of the cross-connection's data transmission capacity, which is carried out in the solution according to the invention in the optical area located in the middle of Figure 2.
  • Within the wavelength range of 1530 -1560 nm used in the exam- pie it is possible to form a cross-connection apparatus of several terabits, wherein there can be thousands of wavelengths, that is, in practice thousands of bit flows within the said area.
  • the connections and components presented in the example are only one manner of embodying the invention, and they do not restrict the invention in any way. Nor are the distances be- tween connections shown in Figure 2 restricted, in other words, the shown solution is also suitable e.g. as the solution for a star network.

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

Abstract

L'invention concerne un procédé et un dispositif de brassage optique à très haute capacité, destiné à un système de télécommunication optique fondé sur la technologie du multiplexage en longueur d'ondes (WDM), et en particulier aux noeuds de réseau de ce système. Les applications de cette invention sont conçues pour utiliser une couche de transmission cohérente ainsi qu'une architecture à diffusion et sélection. Dans la solution proposée, des transducteurs optoélectroniques sont placée à la fois du côté entrée et du côté sortie de la zone de brassage. Une modulation en bande étroite est en outre utilisée. Le signal envoyé au dispositif de brassage est modulé dans un modulateur à bande latérale unique (SSB), ce qui permet de réduire la largeur de bande du signal optique. Grâce à l'émission dans une seule bande étroite, les signaux peuvent être rapprochés très près les uns des autres, ce qui permet de multiplier le nombre de longueurs d'ondes d'un facteur de 2 à 10 à l'intérieur du même intervalle de longueurs d'ondes que celui des brasseurs antérieurs. Ainsi dans l'intervalle de longueurs d'ondes 1530-1560 nm qui est souvent utilisé dans la transmission optique de données, on peut installer un dispositif de brassage de plusieurs térabits, permettant la transmission de milliers de longueurs d'ondes. Cependant la présente solution n'est pas limitée à un quelconque intervalle de longueurs d'ondes et peut s'appliquer non seulement aux fibres optiques, mais également à la transmission optique dans l'espace.
PCT/FI2000/000226 1999-04-15 2000-03-17 Procede et dispositif permettant la realisation d'un brasseur optique WO2000064078A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU35599/00A AU3559900A (en) 1999-04-15 2000-03-17 Method and apparatus for implementing an optical cross-connection

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI990836 1999-04-15
FI990836A FI990836A7 (fi) 1999-04-15 1999-04-15 Menetelmä optisen ristikytkennän toteuttamiseksi ja ristikytkentälaite

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WO2000064078A1 true WO2000064078A1 (fr) 2000-10-26

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WO (1) WO2000064078A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1686715A1 (fr) * 2005-01-31 2006-08-02 Fujitsu Ltd. Système de réseau optique et dispositif de transmission

Citations (7)

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Publication number Priority date Publication date Assignee Title
US4821255A (en) * 1987-05-06 1989-04-11 Bell Communications Research, Inc. Cross-connection of wavelength-division-multiplexed high speed optical channels
EP0688114A1 (fr) * 1994-06-17 1995-12-20 AT&T Corp. Système de télécommunication bidirectionnel à fibre optique utilisant une source à plusieurs longueurs d'ondes à un mode de division au longueur d'onde (WDM) intégrée monolithique et une source optique et incohérente à large bande
US5519526A (en) * 1992-10-21 1996-05-21 California Institute Of Technology Optical protocols for communication networks
US5784184A (en) * 1995-05-11 1998-07-21 Ciena Corporation WDM Optical communication systems with remodulators and remodulating channel selectors
EP0855617A2 (fr) * 1997-01-24 1998-07-29 Gpt Limited Modulateurs à bande latéral unique
WO1998033287A1 (fr) * 1997-01-27 1998-07-30 British Telecommunications Public Limited Company Systeme de communication presentant une topologie en etoile
WO2000004669A1 (fr) * 1998-07-20 2000-01-27 Sarnoff Corporaton Systemes de commutation optique multiplexes par repartition en longueur d'onde dense multilongueurs d'onde

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4821255A (en) * 1987-05-06 1989-04-11 Bell Communications Research, Inc. Cross-connection of wavelength-division-multiplexed high speed optical channels
US5519526A (en) * 1992-10-21 1996-05-21 California Institute Of Technology Optical protocols for communication networks
EP0688114A1 (fr) * 1994-06-17 1995-12-20 AT&T Corp. Système de télécommunication bidirectionnel à fibre optique utilisant une source à plusieurs longueurs d'ondes à un mode de division au longueur d'onde (WDM) intégrée monolithique et une source optique et incohérente à large bande
US5784184A (en) * 1995-05-11 1998-07-21 Ciena Corporation WDM Optical communication systems with remodulators and remodulating channel selectors
EP0855617A2 (fr) * 1997-01-24 1998-07-29 Gpt Limited Modulateurs à bande latéral unique
WO1998033287A1 (fr) * 1997-01-27 1998-07-30 British Telecommunications Public Limited Company Systeme de communication presentant une topologie en etoile
WO2000004669A1 (fr) * 1998-07-20 2000-01-27 Sarnoff Corporaton Systemes de commutation optique multiplexes par repartition en longueur d'onde dense multilongueurs d'onde

Non-Patent Citations (1)

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Title
JOHANSSON S. ET AL.: "A cost-effective approach to introduce an optical WDM network in the metropolitan environment", IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, vol. 16, no. 7, September 1998 (1998-09-01), pages 1109 - 1122, XP002932702 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1686715A1 (fr) * 2005-01-31 2006-08-02 Fujitsu Ltd. Système de réseau optique et dispositif de transmission
JP2006211591A (ja) * 2005-01-31 2006-08-10 Fujitsu Ltd 光ネットワークシステムおよび伝送装置
US7826744B2 (en) 2005-01-31 2010-11-02 Fujitsu Limited Optical network system and transmission apparatus

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Publication number Publication date
FI990836A7 (fi) 2000-10-16
AU3559900A (en) 2000-11-02
FI990836A0 (fi) 1999-04-15

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