Optical line terminal arrangement, apparatus and methods

• US 9,014,562 B2
• Filed: 03/05/2008
• Issued: 04/21/2015
• Est. Priority Date: 12/14/1998
• Status: Expired due to Fees

• Current Assignee: Coriant Operations, Inc. (Infinera Corp.)
• Original Assignee: Coriant Operations, Inc. (Infinera Corp.)
• Inventors: Gerstel, Ornan A., Ramaswami, Rajiv
• Primary Examiner(s): Sedighian, M. R.
• Application Number:
  US12/042,793
• Publication Number:
  US 20080219666A1
• Time in Patent Office: 2,603 Days
• Field of Search: 398/79, 398/82, 398 42- 74, 398/95
• US Class Current: 398/79
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• 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 14/0216 Bidirectional architectures
• CPC Class Codes: H04J 14/022 For interconnection of WDM optical networks
• CPC Class Codes: H04J 14/0278 WDM optical network architectures
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0286 WDM hierarchical architectures

Abstract

A wavelength division multiplexed optical communication system includes a plurality of optical line terminals which may be part of separate in service networks, each having a line interface and an all-optical pass-through interface including a plurality of pass-through optical ports, and each also including a plurality of local optical ports which are connectable to client equipment and an optical multiplexer/demultiplexer for multiplexing/demultiplexing optical wavelengths. The optical multiplexer/demultiplexer may include one or more stages for inputting/outputting individual wavelengths or bands of a predetermined number of wavelengths, or a combination of bands and individual wavelengths. At least one of the pass-through optical ports of an optical line terminal of one network may be connected to at least one of the pass-through optical ports of an optical line terminal of another network to form an optical path from the line interface of the optical line terminal of the one network to the line interface of the optical line terminal of the another network to form a merged network. The use of such optical line terminals allows the upgrading and merging of the separate networks while in service.

Claims

1. A wavelength division multiplexed (WDM) optical communication system comprising:

a first optical line terminal having an input line-side interface adapted to receive a WDM optical communication signal communicated to the system across an optical fiber, a first transponder, an optical splitter coupled to the first transponder, a first all-optical pass-through interface, and a second all-optical pass-through interface;

a second optical line terminal having an output line-side interface adapted to transmit a WDM optical communication signal from the system across an optical fiber, an optical switch that can be used to select a wavelength to couple to said output line-side interface, and a first all-optical pass-through interface; and

a third optical line terminal having an output line-side interface adapted to transmit a WDM optical communication signal from the system across an optical fiber, and a first all-optical pass-through interface;

the first all-optical pass-through interface of said first optical line terminal being connected to the first all-optical pass-through interface of said second optical line terminal to couple a first wavelength from the input line-side interface of said first optical line terminal through said splitter to said first transponder and, if said switch selects said wavelength, through said splitter and said switch to the output line-side interface of said second optical line terminal,

the second all-optical pass-through interface of said first optical line terminal being connected to the first all-optical pass-through interface of said third optical line terminal to couple a second wavelength from the input line-side interface of said first optical line terminal to the output line-side interface of said third optical line terminal,

said second optical line terminal further comprising a second transponder, wherein said switch couples a wavelength from said second transponder to the output line-side interface of said second optical line terminal through said switch if said switch alternatively selects said wavelength.

2. The wavelength division multiplexed optical communication system of claim 1, wherein said third optical line terminal further comprises an input line-side interface adapted to receive a WDM optical communication signal communicated to the system across an optical fiber, and a second all-optical pass-through interface connected to a second all-optical pass-through interface of said second optical line terminal to couple a wavelength from the input line-side interface of said third optical line terminal to the output line-side interface of said second optical line terminal through said optical switch if said switch alternatively selects said wavelength.

3. The wavelength division multiplexed optical communication system of claim 2, wherein said first all-optical pass-through interface of said first optical line terminal is connected to the first all-optical pass-through interface of said second optical line terminal through a first optical fiber, and said second all-optical pass-through interface of said first optical line terminal is connected to the first all-optical pass-through interface of said third optical line terminal through a second optical fiber that is not the first optical fiber, and said second all-optical pass-through interface of said third optical line terminal is connected to said second all-optical pass-through interface of said second optical line terminal through a third optical fiber that is not the first optical fiber and that is not the second optical fiber, and wherein the system is further adapted to communicate optical signals bidirectionally through each of said all-optical pass-through interfaces, and wherein an interface that is the input line-side interface of said third optical line terminal is also an output line-side interface.

4. An optical wavelength division multiplexed (WDM) add/drop multiplexing system, comprising:

a first input line-side interface and an output line-side interface;

a first transponder to which a first optical path of the system extends from the first input line-side interface, wherein the first transponder is an electro-optical conversion (OEO) device configured to receive a network-side optical signal and in response output a client-side optical signal, and wherein the system is operable to communicate a wavelength along the first optical path from the first input line-side interface to the first transponder to drop the wavelength, and wherein along the first optical path, between the first input line-side interface and the first transponder, the first optical path is established by at least an optical splitter;

a second transponder, wherein the second transponder is an electro-optical conversion (OEO) device configured to receive a client-side optical signal and in response output a network-side optical signal;

a second optical path, wherein in a first state of the system the second optical path extends from the first input line-side interface to the output line-side interface and, along the second optical path between the first input line-side interface and the output line-side interface, is established by at least the optical splitter and an optical switch, and wherein in the first state of the system the system is operable to communicate a wavelength along the second optical path from the first input line-side interface to the output line-side interface without any intervening electro-optical conversion (OEO) to pass the wavelength;

and wherein in a second state of the system the second optical path alternatively extends from the second transponder to the output line-side interface and, along the second optical path between the second transponder and the output line-side interface, is established by at least the optical switch, and wherein in the second state of the system the system is operable to communicate a wavelength along the second optical path from the second transponder to the output line-side interface to add the wavelength;

and wherein the optical splitter is configured to receive an optical signal comprising at least one wavelength, and to output at least two optical signals each comprising the at least one wavelength, wherein one of the at least two optical signals is output on the first optical path, and another of the at least two optical signals is output on an optical path that is the second optical path in at least the first state of the system and is not the first optical path.

5. The optical add/drop multiplexing system of claim 4, further comprising a second input line-side interface that is not the first input line-side interface, and wherein in a third state of the system the second optical path alternatively extends from the second input line-side interface to the output line-side interface and, along the second optical path between the second input line-side interface and the output line-side interface, is established by at least the optical switch, and wherein in the third state of the system the system is operable to communicate a wavelength along the second optical path from the second input line-side interface to the output line-side interface without any intervening electro-optical conversion (OEO) to pass the wavelength.

6. An optical wavelength division multiplexed (WDM) add/drop multiplexing system, comprising:

a first input line-side interface;

an output line-side interface;

an optical demultiplexer configured to receive a plurality of wavelengths multiplexed together as an optical signal, and to output each of the plurality of wavelengths as an individual wavelength;

an optical multiplexer configured to receive a plurality of individual wavelengths, and to output the plurality of wavelengths multiplexed together as an optical signal;

a first transponder to which a first optical path of the system extends from the first input line-side interface, wherein the first transponder is an electro-optical conversion (OEO) device configured to receive a network-side optical signal and in response output a client-side optical signal, and wherein the system is operable to communicate a wavelength along the first optical path from the first input line-side interface to the first transponder to drop the wavelength, and wherein along the first optical path, between the first input line-side interface and the first transponder, the first optical path is established by at least an optical splitter;

a second transponder, wherein the second transponder is an electro-optical conversion (OEO) device configured to receive a client-side optical signal and in response output a network-side optical signal;

an optical switch;

a second optical path, wherein in a first state of the system;

the second optical path extends from the first input line-side interface to the output line-side interface and is established by at least the optical splitter, the optical demultiplexer, the optical switch and the optical multiplexer;

along the second optical path, between the first input line-side interface and the optical switch, the second optical path is established by at least the optical splitter;

along the second optical path, between the optical splitter and the optical multiplexer and also between the optical demultiplexer and the optical multiplexer, the second optical path is established by at least the optical switch;

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer;

along the second optical path, between the first input line-side interface and the optical switch, the second optical path is established by at least the optical demultiplexer; and

the system is operable to communicate a wavelength along the second optical path from the first input line-side interface to the output line-side interface without any intervening electro-optical conversion (OEO) to pass the wavelength;

and wherein in a second state of the system;

the second optical path alternatively extends from the second transponder to the output line-side interface and is established by at least the optical switch and the optical multiplexer;

along the second optical path, between the second transponder and the optical multiplexer, the second optical path is established by at least the optical switch;

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer; and

the system is operable to communicate a wavelength along the second optical path from the second transponder to the output line-side interface to add the wavelength;

and wherein the optical splitter is not the optical demultiplexer, and wherein the optical splitter is configured to receive an optical signal comprising at least one wavelength, and to output at least two optical signals each comprising the at least one wavelength, wherein one of the at least two optical signals is output on the first optical path, and another of the at least two optical signals is output on an optical path that is the second optical path in at least the first state of the system and is not the first optical path.

7. The optical add/drop multiplexing system of claim 6, further comprising a second input line-side interface that is not the first input line-side interface, and wherein in a third state of the system:

the second optical path alternatively extends from the second input line-side interface to the output line-side interface and is established by at least the optical switch and the optical multiplexer;

along the second optical path, between the second input line-side interface and the optical multiplexer, the second optical path is established by at least the optical switch;

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer; and

the system is operable to communicate a wavelength along the second optical path from the second input line-side interface to the output line-side interface without any intervening electro-optical conversion (OEO) to pass the wavelength.

8. A method for an optical add/drop multiplexing system in an optical wavelength division multiplexed (WDM) network environment, comprising the steps of:

establishing a first optical path extending from a first input line-side interface of the system to a first transponder, wherein the first transponder is an electro-optical conversion (OEO) device configured to receive a network-side optical signal and in response output a client-side optical signal, and wherein along the first optical path, between the first input line-side interface and the first transponder, the first optical path is established by at least an optical splitter;

establishing a second optical path, wherein in a first state of the system;

the second optical path extends from the first input line-side interface to an output line-side interface and is established by at least the optical splitter, a first optical port, a second optical port that is not the first optical port, an optical demultiplexer, an optical switch and an optical multiplexer, and wherein the optical demultiplexer is configured to receive a plurality of wavelengths multiplexed together as an optical signal and to output each of the plurality of wavelengths as an individual wavelength, and wherein the optical multiplexer is configured to receive a plurality of individual wavelengths and to output the plurality of wavelengths multiplexed together as an optical signal;

along the second optical path, between the first input line-side interface and the first optical port, the second optical path is established by at least the optical splitter;

along the second optical path, between the optical splitter and the second optical port, the second optical path is established by at least the first optical port;

along the second optical path, between the first optical port and the optical switch, the second optical path is established by at least the second optical port;

along the second optical path, between the second optical port and the optical multiplexer and also between the optical demultiplexer and the optical multiplexer, the second optical path is established by at least the optical switch;

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer;

along the second optical path, between the first input line-side interface and the optical switch, the second optical path is established by at least the optical demultiplexer;

the second optical path extends from the first input line-side interface to the optical splitter in common with the first optical path; and

the second optical path extends from the optical splitter to the output line-side interface not in common with the first optical path;

and wherein in a second state of the system;

the second optical path alternatively extends from a second transponder to the output line-side interface and is established by at least the optical switch and the optical multiplexer, wherein the second transponder is an electro-optical conversion (OEO) device configured to receive a client-side optical signal and in response output a network-side optical signal;

along the second optical path, between the second transponder and the optical multiplexer, the second optical path is established by at least the optical switch; and

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer;

and wherein in a third state of the system;

the second optical path alternatively extends from a second input line-side interface to the output line-side interface and is established by at least the optical switch and the optical multiplexer, wherein the second input line-side interface is not the first input line-side interface;

along the second optical path, between the second input line-side interface and the optical multiplexer, the second optical path is established by at least the optical switch; and

along the second optical path, between the optical switch and the output line-side interface, the second optical path is established by at least the optical multiplexer;

communicating along the first optical path, from the first input line-side interface to the first transponder, a wavelength of a WDM optical signal received by the system at the first input line-side interface, to drop the wavelength;

in the first state of the system, communicating without any intervening electro-optical conversion (OEO) along the second optical path a wavelength of the WDM optical signal received by the system at the first input line-side interface, to pass the wavelength to a WDM optical signal transmitted by the system from the output line-side interface;

in the second state of the system, alternatively communicating along the second optical path a wavelength to add the wavelength to a WDM optical signal transmitted by the system from the output line-side interface;

in the third state of the system, alternatively communicating along the second optical path a wavelength of a WDM optical signal received by the system at the second input line-side interface, to pass the wavelength to a WDM optical signal transmitted by the system from the output line-side interface; and

wherein the optical splitter is not the optical demultiplexer, and wherein the optical splitter is configured to receive an optical signal comprising at least one wavelength, and to output at least two optical signals each comprising the at least one wavelength, wherein one of the at least two optical signals is output on the first optical path, and another of the at least two optical signals is output on another optical path that is the second optical path in at least the first state of the system.

9. The method of claim 8, wherein at least a portion of the first optical path extends from one modular card to another modular card, and wherein the system is further adapted to communicate optical signals bidirectionally through at least the first and second optical ports.

10. The method of claim 8, wherein at least a portion of the second optical path extends from one modular card to another modular card in at least the first state of the system.

11. The method of claim 10, wherein at least a portion of the second optical path extends from one modular card to another modular card in each of the second state of the system and the third state of the system.