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

• US 7,835,645 B2
• Filed: 02/20/2007
• Issued: 11/16/2010
• Est. Priority Date: 02/21/2006
• Status: Expired due to Fees

• Current Assignee: ADVA Optical Networking SE (ADTRAN Holdings, Inc.)
• Original Assignee: ADVA Optical Networking SE (ADTRAN Holdings, Inc.)
• Inventors: Eiselt, Michael
• Primary Examiner(s): Vanderpuye; Ken N
• Assistant Examiner(s): Jacob; Oommen
• Application Number:
  US11/676,992
• Publication Number:
  US 20070196106A1
• Time in Patent Office: 1,365 Days
• Field of Search: 398/83, 398/50
• US Class Current: 398/83
• 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. 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. 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.

Claims

1. An optical circuit structure for realizing a higher-order node in an optical transmission network comprising:

(a) a number N of bidirectional remote ports, each remote port operable to receive a respective one of a number N of optical receive wavelength division multiplexed signals (R-WDM signals) each having a set of optical receive channels, each remote port operable to output a respective optical transmit wavelength division multiplexed signal (T-WDM signal) having a set of optical transmit channels, wherein a respective 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) a number M of bidirectional local ports, M being greater than or equal to one and less than or equal to N, each of the M local ports being associated with a respective selected one of the N remote ports, each local port being operable to receive one or more optical add channels and output one or more optical drop channels;

(c) one or more optical drop channel circuits for feeding selected optical channels of respective ones of the N R-WDM signals as drop channels to respective selected ones of the M local ports, and for guiding the respective R-WDM signals as cross-connect wavelength division multiplexed signals (cross-connect WDM signals) toward the relevant remote port, each drop channel circuit including an optical splitter unit splitting the respective R-WDM signal and an optical demultiplexing unit connected to an output port of the optical splitter unit;

(d) a number N of optical add and cross-connect circuits for guiding the respective R-WDM signals as cross-connect wavelength division multiplexed signals (cross-connect WDM signals) toward the relevant remote port, and for generating a respective one of the optical T-WDM signals for each of the N remote ports, each optical acid and cross-connect circuit for extracting certain receive channels as pass-through channels from the R-WDM signals of one or more of the other remote ports and combining together with the selected ones of the one or more add channels optionally added to the respective T-WDM signal that can be output from the relevant remote port, each add and cross connect circuit comprising;

(1) an optical add circuit for receiving selected ones of the cross-connect WDM signals and generating two or more sub-transmit wavelength division multiplexed signals (sub-transmit WDM signals) for the relevant remote port, the optical add circuit comprising two or more of the following;

(i) one or more first optical add demultiplexing units each including a first demultiplexing unit, a number of channel input ports, a number of optical 2×

1 switches according to the number of channels of a corresponding WDM signal, and a multiplexing unit, each of the first optical add demultiplexing units for combining respective pairs of the cross-connect WDM signals into a respective sub-transmit WDM signal, a first one of the pair of cross-connect WDM signals being connected to an input of the first demultiplexing unit, wherein channel output ports of the first demultiplexing unit are each connected to respective first input ports of the optical 2×

1 switches, a second one of the pair of cross-connect WDM signals being connected to an input of a second demultiplexing unit connected to the first optical add demultiplexing unit and having channel output ports connected to the channel input ports of the optical add demultiplexing unit, channel output ports of the second demultiplexing unit being connected to second input ports of the optical 2×

1 switches, the output ports of the 2×

1 switches connected to inputs ports of the multiplexing unit, the output of the multiplexing unit for providing a respective one of the sub-transmit WDM signals;

(ii) a single second optical add demultiplexing unit including a first demultiplexing unit, a number of channel input ports, a number of optical 2×

1 switches according to the number of corresponding WDM signal, and a multiplexing unit, for combining a cross-connect WDM signal and an optionally existing add channels into another respective one sub-transmit WDM signal;

(iii) if the number of cross-connect WDM signals is even, the optical add circuit further includes a single third optical add demultiplexing unit including a first demultiplexing unit, a number of channel input ports, a number of optical 2×

1 switches according to the number of corresponding WDM signal, and a multiplexing unit, for converting a selected remaining cross-connect WDM signal converted into another respective one sub-transmit WDM signal; and

(2) an optical splitter unit associated with the relevant remote port, the optical splitter units for combining the two or more sub-transmit wavelength division multiplexed signals into the T-WDM signal that can be output from the relevant remote port.

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

3. The optical circuit structure of claim 1, wherein the optical add and cross connect circuit of at least one remote port is for generating the respective T-WDM signal using all cross-connect WDM signals of the other remote ports.

4. The optical circuit structure of claim 1, wherein the one or more optical drop channel circuits is for generating the N−

1 cross-connect WDM signals by means of N optical 1;

(N−

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

5. The optical circuit structure of claim 1, further comprising N optical 1:

N splitter units, to each of which is connected the R-WDM signal of a respective remote port, the N optical 1;

N splitter units for generating the N cross-connect wavelength division multiplexed signals.

6. The optical circuit structure of claim 1, wherein the number M of local ports is equal to the number N of remote ports.

7. The optical circuit structure of claim 1, wherein a wavelength division demultiplexing unit is adapted to demultiplex the receive wavelength division multiplexed signal of the associated remote port connected to a local port into the individual drop channels.

8. The optical circuit structure of claim 1, wherein 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.

9. The circuit structure of claim 1, wherein the optical drop channel circuits and the optical add and cross-connect circuits consist essentially of optical splitter units, optical demultiplexing units, optical add units, and optical interconnections therebetween.

10. An optical expansion circuit for expanding a first optical circuit, the first optical circuit for realizing a second order or higher node, the expansion circuit to realize a higher order node than the first optical circuit, wherein:

the first optical circuit structure includes, for each of the two remote ports, an optical base circuit comprising;

(a) a 1;

2 splitter unit for generating respective drop channels and a 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 therefrom the transmit wavelength division multiplexed signal for the relevant remote port;

and wherein the optical expansion circuit comprises;

(b) a combination of an optical add unit and a multiplexing unit, the optical add unit including 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 a channel output port of the wavelength division demultiplexing unit connects individual output channels to a first input port of a corresponding numbers of optical 2×

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

1 switches, 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 switches 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, the multiplexing unit for generating a respective transmit wavelength division multiplexed signal or a sub-transmit wavelength division multiplexed signal, wherein a first additional cross-connect wavelength division multiplexed signals is fed to the input port of the add unit and a second additional cross-connect wavelength division multiplexed signals is fed to the input of the demultiplexing unit, and wherein the channels generated on the output side by the demultiplexing unit are each fed to a second input port of a respective 2×

1 switch;

(c) an optical 2;

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

1 splitter unit is connected to the output port of the add unit; and

(d) an optical 1;

3 splitter unit, wherein an input port of the 1;

3 splitter unit is connected to one output port of the 2;

1 splitter unit.

11. An optical circuit structure for a third or fourth-order node using optical expansion circuits according to claim 10, wherein:

(a) an optical base circuit and an optical expansion circuit according to claim 10 are provided for each of the three or four remote ports;

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

(1) a first cross-connect wavelength division multiplexed signal and optionally the add channels of the relevant local port are connected to the add unit of the base circuit;

(2) a second cross-connect wavelength division multiplexed signal is connected to the input port of the add unit or to the input port of the demultiplexing unit of the expansion circuit;

(3) in the case of realizing a fourth-order node, a third cross-connect wavelength division multiplexed signal is connected to the input port of the demultiplexing unit of the expansion circuit or to the input port of the add unit of the expansion circuit;

(4) the output port of the add unit of the base circuit is connected to an input port of the 2;

1 splitter unit of the expansion circuit;

(5) wherein the transmit wavelength division multiplexed signal for the relevant remote port is generated at the output port of the 2;

1 splitter unit;

(c) the output port of the 1;

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

3 splitter unit of the expansion circuit; and

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

3 splitter unit of the expansion circuit is provided as an input cross-connect wavelength division multiplex signal to the base circuits or expansion circuits of each other remote port.

12. An optical circuit structure for a fifth or sixth-order node using optical expansion circuits according to claim 10, comprising:

(a) means for realizing a fourth-order node by creating one or two first additional remote ports added to the circuit structure of claim 10;

(b) means for realizing one or two second additional ports, each including a base circuit and one expansion circuit for each second additional remote port provided according to claim 10, wherein the structure for each second additional remote port includes a means for realizing a fourth order node added to the circuit structure of claim 10;

(c) a second expansion circuit for each remote port, wherein, for generating a transmit wavelength division multiplexed signal for each remote port on an output port of a 2;

1 splitter unit of the second expansion circuit,

(1) an output port of a 2;

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

1 splitter unit of the second expansion circuit and accordingly a transmit wavelength division multiplexed signal of the means for realizing a fourth order node used as a sub-transmit wavelength division multiplexed signal;

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

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

(d) an output port of the 1;

3 splitter unit of the first expansion circuit is connected to an input port of a 1;

3 splitter unit of the second expansion circuit; and

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

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

3 splitter unit of the second expansion circuit are provided as cross connect wavelength division multiplexed signals to the base circuits or expansion circuits of the other remote ports.

13. An optical circuit structure for a node of the order six plus 2n, wherein n is a whole natural number, using optical expansion circuits according to claim 10, comprising:

(a) a means for providing a sixth order node using optical expansion circuits according to claim 10 is expanded by one base circuit and two expansion circuits for each additional order for creating the additional remote ports, wherein the structure for each remote port corresponds to the means for providing a sixth order node; and

(b) wherein the structure expanded in this way is expanded by a number n of expansion circuits for each remote port, wherein for each remote port two successive expansion circuits are connected, and wherein the transmit wavelength division multiplexed signal is generated for each remote port at the output port of a 2;

1 splitter unit of a selected final expansion circuit.

14. An expanded optical circuit structure for realizing a third or fourth-order node with three or more remote ports, comprising:

(a) a base circuit structure provided for each remote port, including;

(i) an optical add demultiplexing unit including a first demultiplexing unit, a number of channel input ports, a number of optical 2×

1 switches according to the number of corresponding WDM signal, and a multiplexing unit, having an output port connected to a first input port of a 2;

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

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

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

(ii) a 1;

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

2 splitter unit; and

(iii) with a 1;

m splitter unit having an input port 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 a cross-connect wavelength division multiplexed signal for feeding to other remote ports is generated at the output ports of the 1;

m splitter unit

wherein a 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 an expansion circuit structure is provided composed of an additional add unit that is combined with a demultiplexing unit, where demultiplexing output ports of the demultiplexing unit are connected to the input ports of the 2×

1 switches of the add unit, an output port of the add unit being connected to a free input port of the 2;

1 splitter unit of the base circuit structure; and

(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.

15. An expanded optical circuit structure realizing a node of order N greater than or equal to 5, using the structure of claim 14, wherein:

(a) for each additional remote port, an additional base circuit structure 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 pair of additional remote ports, to each additional remote port, 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 switches 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) 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) 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) 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) 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.