Low cost secure submarine ROADM branching unit using bidirectional wavelength-selective switch

• US 9,654,246 B2
• Filed: 11/11/2015
• Issued: 05/16/2017
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Aida, Ryuji, Ji, Philip Nan, Wang, Ting
• Primary Examiner(s): Liu, Li
• Application Number:
  US14/938,771
• Publication Number:
  US 20160149663A1
• Time in Patent Office: 552 Days
• Field of Search: 398 82- 88
• 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 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0216 Bidirectional architectures
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/02212 by addition of a dummy signal

Abstract

A reconfigurable optical add/drop multiplexer (ROADM) unit includes a first optical circulator coupled to a first terminal; a second optical circulator coupled to a second terminal; a third optical circulator coupled to a third terminal; a fourth optical circulator coupled to a fourth terminal; a first wavelength-selective switch (WSS), coupled to the first, second, and third optical circulators; a second WSS coupled to the first, second, and fourth optical circulators, wherein the first and second WSSes are bidirectional operated; a first 1:2 coupler positioned between the first circulator and the first and second WSSes; a second 1:2 coupler positioned between the second circulator and the first and second WSSes.

Claims

1. A system for communicating in a submarine transmission network, comprising:

first, second, third and fourth bi-directional terminals; and

a reconfigurable optical add/drop multiplexer (ROADM) unit coupled to the terminals, including;

a first optical circulator coupled to the first terminal;

a second optical circulator coupled to the second terminal;

a

third optical circulator coupled to the third terminal;

a fourth optical circulator coupled to the fourth terminal;

a first wavelength-selective switch (WSS), coupled to the first, second, and third optical circulators;

a second WSS coupled to the first, second, and fourth optical circulators, wherein the first and second WSSes are bidirectional operated;

a first 1;

2 coupler positioned between the first circulator and the first and second WSSes;

a second 1;

2 coupler positioned between the second circulator and the first and second WSSes, wherein input signal from terminals are broadcast into two paths, one of which is an opposite terminal and sent through by one WSS for add/drop reconfiguration;

a controller specifying symmetric wavelength assignments to the WSSes for simultaneous use in both directions;

a power switched branching unit (PSBU) coupled to the ROADM unit;

dummy lights used to balance total power, wherein the dummy lights are reused in the ROADM unit.

2. The system of claim 1, wherein each optical circulator comprises a 3-port circulator.

3. The system of claim 1, wherein the first WSS is configured according to a wavelength plan and picks up only channels intended for the second terminal and discards remaining channels.

4. The system of claim 1, wherein the WSSes select each individual channel to one of two inputs independently.

5. The system of claim 1, wherein input wavelength is assigned to avoid wavelength contention between first to second channels and third to second channels.

6. The system of claim 1, wherein each WSS selects intended channels and discards dummy signals.

7. The system of claim 1, wherein both WSSes have a predetermined wavelength configuration, and two opposite direction operations of each WSS also have the predetermined wavelength configuration.

8. The system of claim 1, wherein the ROADM unit is used in a submarine Branching Unit within the submarine transmission network.

9. The system of claim 1, wherein the WSS comprises a 2×

1 WSS.

10. The system of claim 1, wherein the circulators and WSSes are interconnected through optical fibers.