DIRECTIONLESS AND COLORLESS RECONFIGURABLE OPTICAL ADD/DROP MULTIPLEXER

• US 20120027408A1
• Filed: 07/28/2010
• Published: 02/02/2012
• Est. Priority Date: 07/28/2010
• Status: Active Grant

• Current Assignee: Adtran Networks SE (ADTRAN Holdings, Inc.)
• Original Assignee: ADVA Optical Networking SE (ADTRAN Holdings, Inc.)
• Inventors: Atlas, Dogan, Wu, Xiaoping
• Granted Patent: US 8,903,242 B2
• Time in Patent Office: Days
• US Class Current: 398/58
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0205 Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
• CPC Class Codes: H04J 14/021 Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/02122 Colourless, directionless or contentionless [CDC] arrangements
• CPC Class Codes: H04J 14/0217 Multi-degree architectures, e.g. having a connection degree greater than two
• CPC Class Codes: H04J 14/022 For interconnection of WDM optical networks
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant

Abstract

The invention relates to a directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) for a number of clients comprising:

• an add/drop interface for optical signals of at least one optical network,
• wherein each received optical signal is split by at least one optical splitter into optical signals which are applied to a downstream cross connector distributing the split optical signals to wavelength selectors of different clients,
• wherein each wavelength selector performs a wavelength selection of at least one wavelength from the distributed optical signals,
• wherein an optical signal having a selected wavelength (λ) is applied to a client transponder of a client.

Claims

1. A directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) for a number of clients comprising:

an add/drop interface for optical signals of at least one optical network,

wherein each received optical signal is split by at least one optical splitter into optical signals which are applied to a downstream cross connector distributing the split optical signals to wavelength selectors of different clients,

wherein each wavelength selector performs a wavelength selection of at least one wavelength from the distributed optical signals,

wherein an optical signal having a selected wavelength (A) is applied to a client transponder of a client.

2. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein said optical add/drop interface is adapted to connect said ROADM to a number (M) of optical networks.

3. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 2,

wherein M passive (1×

R) optical splitters are provided each passive (1×

R) optical splitter being adapted to split an optical signal received from a optical network via said add/drop interface in several (R) optical signals each being applied to one of M passive (1×

N) optical splitters, each passive (1×

N) optical splitter being adapted to split an optical signal received from a passive (1×

N) optical splitter into several (N) optical signals applied to a (M×

N) downstream cross connector, said downstream cross connector distributing the split optical signals to N (M×

1) wavelength selectors of N different clients, wherein each (M×

1) wavelength selector is connected to a corresponding client transponder of a client, or distributing the split optical signals to N(M×

S) wavelength selectors of N×

S different clients, wherein each (M×

S) wavelength selector is connected to several (S) client transponders of a group of (N) clients.

4. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 3,

wherein said client comprises a client terminal or a client network.

5. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein an optical signal received by said add/drop interface is amplified by an optical amplifier to compensate for losses caused by the respective optical splitter.

6. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein the split optical signals split by an optical splitter are amplified by optical amplifiers to compensate for losses caused by said optical splitter.

7. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein said wavelength selector comprises a wavelength selective switch (WSS).

8. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 7,

wherein said wavelength-selective switch (WSS) is a channelized or gridless wavelength-selective switch having a variable granularity.

9. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein each wavelength selector comprises a (M×

1) whitelight switch and a (1×

1) wavelength-selective switch (WSS).

10. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein each wavelength selector comprises a (M×

1) whitelight switch and a tunable filter comprising at least a grating, a thin film filter, a liquid crystal, a LCOS, a DLP or a MEMS.

11. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein each client transponder is connected to a corresponding (1×

M) optical switch switching an optical signal transmitted by said client transponder to an upstream cross connector distributing the transmitted optical signals to M optical combiners connected to said optical add/drop interface.

12. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 11,

wherein said downstream cross connector and said upstream cross connector are hardwired devices.

13. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 11,

wherein said downstream cross connector and said upstream cross connector are programmable devices.

14. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein the number (M) of optical networks is within a range between one to eight or more optical networks.

15. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein the number (N) of client transponders is within a range between one and sixteen or more client transponders.

16. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 1,

wherein the optical signal is transmitted in a predetermined frequency band between 1528 nm and 1568 nm or beyond.

17. A directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) for a number of clients comprising:

an add/drop interface for optical signals of at least one optical network,

wherein each optical signal is split by at least one optical splitter into optical signals which are applied to at least one contentionless downstream (M×

S) wavelength selective switch switching the split optical signals to client transponders of S different clients.

18. The directionless and colorless reconfigurable optical add/drop multiplexer (ROADM) according to claim 17,

wherein in contentionless downstreams (M×

S) wavelength selective switch is a directionless, colorless and non-blocking wavelength selective switch.

19. A method for dropping an optical signal with a selectable wavelength (λ

) at different clients comprising the steps of;

splitting the optical signal into several optical signals;

distributing the split optical signals to wavelength selectors of all clients;

performing a wavelength selection of the distributed optical signals and

applying an optical signal having the selected wavelength (λ

) to a client.