OPTICAL CIRCUIT STRUCTURE FOR REALIZING A HIGHER-ORDER NODE IN AN OPTICAL TRANSMISSION NETWORK

• US 20070196106A1
• Filed: 02/20/2007
• Published: 08/23/2007
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: ADVA Optical Networking SE (ADTRAN Holdings, Inc.)
• Original Assignee: ADVA Optical Networking SE (ADTRAN Holdings, Inc.)
• Inventors: Eiselt, Michael
• Granted Patent: US 7,835,645 B2
• Time in Patent Office: Days
• US Class Current: 398/43
• 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 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/0217 Multi-degree architectures, e.g. having a connection degree greater than two
• CPC Class Codes: H04J 14/0219 Modular or upgradable architectures

Abstract

The invention relates to an optical circuit structure for realizing a higher-order node in an optical transmission network with a number N of bidirectional remote ports, wherein an optical receive wavelength division multiplexed signal with a set of optical receive channels can be fed to each remote port and wherein an optical transmit wavelength division multiplexed signal with a set of optical transmit channels can be output from each remote port, wherein an optical center wavelength is allocated to each receive channel or transmit channel, and wherein the number N is greater than or equal to three, with a number M of bidirectional local ports, wherein M is greater than or equal to one and less than or equal to N, wherein exactly one defined remote port is associated with each local port and wherein one or more optical add channels can be fed to each local port and one or more optical drop channels can be output from each local port, with optical drop channel means for feeding all or selected optical channels of a receive wavelength division multiplexed signal fed to a certain remote port as drop channels to the relevant local port, and with optical add and cross-connect means which are constructed and which can be configured such that for generating the transmit wavelength division multiplexed signal for each of the N remote ports, several or all of the other remote ports of certain receive channels are extracted as pass-through channels from the receive wavelength division multiplexed signals and are combined together with the optional add channels fed to this remote port into the transmit wavelength division multiplexed signal that can be output from the relevant remote port. According to the invention, the optical drop channel means and the optical add and cross-connect means include exclusively optical splitter units, optical demultiplexing units, and optical add units, wherein for generating each transmit wavelength division multiplexed signal for a certain remote port, the receive wavelength division multiplexed signals of several or all of the other remote ports are guided as cross-connect wavelength division multiplexed signals toward the certain remote port, and wherein the add channels that are fed to a local port associated with the certain remote port are if necessary also guided toward this certain remote port. Depending on the number of cross-connect wavelength division multiplexed signals, one or more sub-transmit wavelength division multiplexed signals for the certain remote port are generated by means of splitter units, add units, and demultiplexing units, and these are finally combined by means of an optical splitter unit into the transmit wavelength division multiplexed signal that can be output from the certain remote port.

Claims

1. Optical circuit structure for realizing a higher-order node in an optical transmission network,

(a) with a number N of bidirectional remote ports, wherein an optical receive wavelength division multiplexed signal with a set of optical receive channels can be fed to each remote port and wherein an optical transmit wavelength division multiplexed signal with a set of optical transmit channels can be output from each remote port, wherein an optical center wavelength is assigned to each receive channel or transmit channel, and wherein the number N is greater than or equal to three,

(b) with a number M of bidirectional local ports, wherein M is greater than or equal to one and less than or equal to N, wherein exactly one defined remote port is associated with each local port, and wherein one or more optical add channels can be fed to each local port and one or more optical drop channels can be output from each local port,

(c) with optical drop channel means for feeding all or selected optical channels of a receive wavelength division multiplexed signal fed to a certain remote port as drop channels to the relevant local port,

(d) with optical add and cross-connect means, which are constructed and which can be configured such that for generating the transmit wavelength division multiplexed signal for each of the N remote ports, certain receive channels are extracted as pass-through channels from the receive wavelength division multiplexed signals of several or all of the other remote ports and combined together with the add channels optionally added to this remote port into the transmit wavelength division multiplexed signal that can be output from the relevant remote port,

characterized in that

(e) the optical drop channel means and the optical add and cross-connect means are composed exclusively of optical splitter units, optical demultiplexing units, and optical add units,

(f) wherein an optical add unit has an optical wavelength division demultiplexing unit connected to an input port for a wavelength division multiplexed signal and a wavelength division multiplexing unit connected to an output port for a wavelength division multiplexed signal, wherein the channel output port of the wavelength division demultiplexing unit guiding the individual channels are each connected to a first input port of an optical 2×

1 switch, wherein an individual additional channel can be fed to a second input port of the optical 2×

1 switch, so that by means of each of the optical 2×

1 switches, either the relevant demultiplexed channel or the relevant additional channel can be fed via the output port of the 2×

1 switch to the relevant channel input port of the wavelength division multiplexing unit, wherein a correspondingly combined wavelength division multiplexed signal is generated at the output port,

(g) for generating the drop channels for each of the M local ports, the receive wavelength division multiplexed signal of each associated remote port generated by means of an optical power splitter unit is fed to the relevant local port and

(h) for generating each transmit wavelength division multiplexed signal for a certain remote port, the receive wavelength division multiplexed signals of several or all of the other remote ports are guided as cross-connect wavelength division multiplexed signals toward the certain remote port, wherein these are generated if necessary by means of an optical power splitter unit, and if necessary the add channels that are fed to a local port associated with the certain remote port are also guided toward the certain remote port,

(i) depending on the number of cross-connect wavelength division multiplexed signals, one or more sub-transmit wavelength division multiplexed signals are generated for the certain remote port according to one or more of the following possibilities;

(i) Every two of the cross-connect wavelength division multiplexed signals are combined into a sub-transmit wavelength division multiplexed signal by means of a combination of an add unit and a demultiplexing unit, wherein one of the cross-connect wavelength division multiplexed signals is fed to the input port of the add unit and the other cross-connect wavelength division multiplexed signal is fed to the input of the demultiplexing unit, wherein the channels generated on the output side by the demultiplexing unit are each fed to a second input port of the 2×

1 switch;

(ii) A cross-connect wavelength division multiplexed signal and/or the optionally existing add channels are combined into a sub-transmit wavelength division multiplexed signal by means of an add unit;

(iii) A single cross-connect wavelength division multiplexed signal is converted into a sub-transmit wavelength division multiplexed signal by means of an add unit; and

(j) the several sub-transmit wavelength division multiplexed signals are combined by means of an optical splitter unit into the transmit wavelength division multiplexed signal that can be output from the certain remote port.

2. Optical circuit structure according to claim 1, characterized in that the optical add units each have an identical structure, wherein the number and spectral position of the channels of the demultiplexing units composed of the add units are identical.

3. Optical circuit structure according to claim 1 or 2, characterized in that the receive wavelength division multiplexed signals of all of the other remote ports are used as cross-connect wavelength division multiplexed signals for generating the transmit wavelength division multiplexed signal for a certain remote port.

4. Optical circuit structure according to claim 3, characterized in that the N−

1 cross-connect wavelength division multiplexed signals are generated by means of N optical 1;

(N−

1) splitter units, to each of which is fed the receive wavelength division multiplexed signal of a remote port.

5. Optical circuit structure according to one of the preceding claims, characterized in that the number M of local ports is equal to the number N of remote ports.

6. Optical circuit structure according to claims 3 and 5, characterized in that the N−

1 cross-connect wavelength division multiplexed signals are generated by means of N optical 1;

N splitter units, to each of which is fed the receive wavelength division multiplexed signal of a remote port.

7. Optical circuit structure according to one of the preceding claims, characterized in that the receive wavelength division multiplexed signal of the associated remote port fed to a local port is demultiplexed by means of a wavelength division demultiplexing unit into the individual drop channels.

8. Optical circuit structure according to one of the preceding claims, characterized in that the optical splitter unit for combining the sub-transmit wavelength division multiplexed signals is constructed in a cascade-like fashion from several optical splitter units, preferably from optical 2:

1 splitter units.

9. Optical expansion module for expanding an optical circuit structure for realizing a node of the second order or higher for an optical circuit structure according to one of the preceding claims,

(a) wherein the optical circuit structure for realizing the second-order node has, for each of the two remote ports, an optical base module that is composed of a 1:

2 splitter unit for generating the drop channels and the cross-connect wavelength division multiplexed signal from the receive wavelength division multiplexed signal of the relevant remote port for the respective other remote port, as well as an add unit to which are fed the add channels for the relevant remote port and the cross-connect wavelength division multiplexed signal and which generates from this the transmit wavelength division multiplexed signal for the relevant remote port, characterized in that

(b) the module has a combination of an add unit according to feature (f) of claim 1 and a demultiplexing unit for generating the transmit wavelength division multiplexed signal or a sub-transmit wavelength division multiplexed signal, wherein a first of the cross-connect wavelength division multiplexed signals is fed to the input port of the add unit and a second of the cross-connect wavelength division multiplexed signals is fed to the input of the demultiplexing unit, wherein the channels generated on the output side by the demultiplexing unit are each fed to a second input port of the 2×

1 switch,

(c) the expansion module includes an optical 2;

1 splitter unit, wherein one input port of the splitter unit is connected to the output port of the add unit, and

(d) the expansion module includes an optical 1;

3 splitter unit.

10. Optical circuit structure for a third or fourth-order node using optical expansion modules according to claim 9, characterized in that

(a) an optical base module and an optical expansion module according to claim 9 are provided for each of the three or four remote ports,

(b) that for generating the transmit wavelength division multiplexed signal for each remote port

(i) a first cross-connect wavelength division multiplexed signal and optionally the add channels of the relevant local port are fed to the add unit of the base module,

(ii) a second cross-connect wavelength division multiplexed signal is fed to the input port of the add unit or to the input port of the demultiplexing unit of the expansion module, and

(iii) in the case of realizing a fourth-order node, a third cross-connect wavelength division multiplexed signal is fed to the input port of the demultiplexing unit or to the input port of the add unit of the expansion module, and

(iv) the output port of the add unit of the base module is connected to an input port of the 2:

1 splitter unit of the expansion module,

(v) wherein the transmit wavelength division multiplexed signal for the relevant remote port is applied to the output port of the 2;

1 splitter unit,

(c) that the output port of the 1;

2 splitter unit of the base module is connected to the input port of the 1;

3 splitter unit of the expansion module, and

(d) that the cross-connect wavelength division multiplexed signal generated at the output ports of the 1;

3 splitter unit of the expansion module is guided in the direction toward the other remote port.

11. Optical circuit structure for a fifth or sixth-order node using optical expansion modules according to claim 9, characterized in that

(a) the structure for a fourth-order node according to claim 10 for creating the one or two additional remote ports is expanded by one base module and one expansion module for each additional remote port, wherein the structure for each remote port corresponds to the structure for each remote port of the circuit structure according to claim 10, and

(b) that the circuit structure expanded in this way is expanded by a second expansion module for each remote port,

(c) that for generating the transmit wavelength division multiplexed signal for each remote port on the output port of the 2:

1 splitter unit of the second expansion module,

(i) the output port of the 2;

1 splitter unit of the first expansion module is connected to the input port of the 2;

1 splitter unit of the second expansion module and accordingly the transmit wavelength division multiplexed signal of the structure according to claim 10 is used as a sub-transmit wavelength division multiplexed signal,

(ii) a fourth cross-connect wavelength division multiplexed signal is fed to the input port of the add unit or to the input port of the demultiplexing unit of the second expansion module, and

(iii) in the case of realizing a sixth-order node, a fifth cross-connect wavelength division multiplexed signal is fed to the input port of the demultiplexing unit or to the input port of the add unit of the second expansion module, and

(d) that an output port of the 1;

3 splitter unit of the first expansion module is connected to the input port of the 1;

3 splitter unit of the expansion module, and

(e) that the cross-connect wavelength division multiplexed signal generated at the other two output ports of the 1;

3 splitter unit of the first expansion module and the three output ports of the 1;

3 splitter unit of the second expansion module is guided toward the other remote ports.

12. Optical circuit structure for a node of the order six plus 2n, wherein n is a whole natural number, using optical expansion modules according to claim 9, characterized in that

(a) the structure according to claim 11 is expanded by one base module and two expansion modules for each additional order for creating the additional remote ports, wherein the structure for each remote port corresponds to the structure for each remote port of the circuit structure according to claim 11, and

(b) the structure expanded in this way is expanded by a number n of expansion modules according to claim 9 for each remote port, wherein for each remote port two successive expansion modules are connected analogous to the connection of the first and second expansion modules of the structure according to claim 11, and wherein the transmit wavelength division multiplexed signal is generated for each remote port in a corresponding way at the output port of the 2:

1 splitter unit of the last added expansion module.

13. Optical base circuit structure for realizing a continuous and expandable second-order node to an optical circuit structure according to one of claims 1 to 8,

(a) with an optical add unit whose output port is connected to a first input port of a 2:

1 splitter unit, wherein the second input port of the 2;

1 splitter unit remains unused in the case of realizing a second-order node and wherein the transmit wavelength division multiplexed signal of the relevant port is generated at the output port of the 2;

1 splitter unit from the add channels optionally fed to the add unit and the cross-connect wavelength division multiplexed signal fed to the input port of the add unit,

(b) with a 1;

2 splitter unit, to which is fed the receive WDM signal of the relevant remote port, wherein the drop channels are output at an output port of the 1;

2 splitter unit, and

(c) with a 1;

m splitter unit whose input port is connected to the other output port of the 1;

2 splitter unit, wherein m is a natural number greater than or equal to two, and wherein the cross-connect wavelength division multiplexed signal for feeding to other remote ports is generated at the output ports of the 1;

m splitter unit.

14. Optical circuit structure for realizing a second-order node, characterized in that an optical base circuit structure according to claim 13 is provided for each of the two remote ports and in that the cross-connect WDM signal generated at an output port of the 1:

m splitter unit of one base circuit structure is fed to the input port of the add unit of the other base circuit structure.

15. Optical circuit structure for realizing a third or fourth-order node, expanded optical circuit structure according to claim 14, characterized in that

(a) a base circuit structure according to claim 13 is added for each additional remote port, wherein the cross-connect wavelength division multiplexed signal generated at an output of the 1:

m splitter unit of one of the other base circuit structures is fed to each add unit of an added base circuit structure, and

(b) that for each remote port an expansion circuit structure is added composed of an additional add unit that is combined with a demultiplexing unit, where the demultiplexing output ports of the demultiplexing unit are connected to the input ports of the 2×

1 switch of the add unit [to which] the free input port of the 2;

1 splitter unit is connected,

(c) wherein for each remote port a second or third cross-connect wavelength division multiplexed signal is fed from one of the output ports of the 1;

m splitter units of the base circuit structures of the other remote ports to the input port of the add unit and/or the input port of the demultiplexing unit of the expansion circuit structure.

16. Optical circuit structure for realizing a node of order N greater than or equal to 5, [of] expanded optical circuit structure according to claim 14, characterized in that

(a) for each additional remote port, a base circuit structure according to claim 13 is added wherein the cross-connect wavelength division multiplexed signal generated at an output of the 1:

m splitter unit of one of the other base circuit structures is fed to each add unit of an added base circuit structure, and

(b) for each remote port for each started pair of added remote ports, an expansion circuit structure is added composed of an additional add unit which is combined with a demultiplexing unit such that the demultiplexing output ports of the demultiplexing unit are connected to the input ports of the 2×

1 switch of the add unit to which the free input port of the 2;

1 splitter unit is connected, and

(c) for each of the remote ports an n;

1 splitter unit is added, wherein the number n designates the number of started pairs of added remote ports,

(d) wherein for each remote port, all of the output ports of the add units of the added expansion circuit structures are connected to the input ports of the 1;

n splitter unit,

(e) wherein for each remote port, the output port of the 1;

n splitter unit is fed to the input port of the 2;

1 splitter unit of the base circuit structure,

(f) wherein for each remote port, one of the cross-connect wavelength division multiplexed signals of the other remote ports is fed to the input ports of the add units and the demultiplexing units, and

(g) wherein for each remote port for generating the cross-connect wavelength division multiplexed signal for the other remote ports, the 1;

m splitter unit of the relevant base circuit structure is expanded if necessary to a 1;

(N−

1) splitter unit.