WDM switch using OADM and control method thereof

• US 6,778,721 B2
• Filed: 09/03/2002
• Issued: 08/17/2004
• Est. Priority Date: 09/04/2001
• Status: Expired due to Fees

• Current Assignee: LG-Ericsson Company Limited (Telefonaktiebolaget LM Ericsson)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Jeong, Kyu-Cheol
• Primary Examiner(s): HEALY, BRIAN
• Application Number:
  US10/232,667
• Publication Number:
  US 20030044110A1
• Time in Patent Office: 714 Days
• Field of Search: 385/15, 385/16, 385/17, 385/18, 385/14, 385/42, 385/40, 385/9, 385/10, 385/31, 385/24, 398/79, 398/82, 398/83, 398/48, 398/45
• US Class Current: 385/15
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12147 Coupler
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 2201/124 interdigital
• CPC Class Codes: G02F 2201/302 grating coupler
• CPC Class Codes: G02F 2203/585 Add/drop devices
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0219 Modular or upgradable architectures

Abstract

A wavelength division multiplexing (WDM) switching includes one or more optical add/drop multiplexers (OADMs) to drop or add optical signals on one or more optical channels. The OADM may be a 1-channel OADM which includes first and second conductors arranged periodically so as to have a pair of different polarities, an optical waveguide type coupler dropping or adding an optical signal of a specific channel by an electric field generated from the first and second conductors, a power supply unit supplying the second conductor with a power, and a switch placed between the second conductor and power supply unit to control a power supply of the second conductor, so as to control generation and termination of the electric field in accordance with an operation control signal. A method of controlling a 1-channel OADM in a WDM system includes checking whether a drop/add operation is demanded or not, forming an electric field at an optical waveguide type coupler if the drop/add operation is demanded, and carrying out the drop/add operation of a channel by the formed electric field.

Claims

1. A WDM switch system, comprising:

a plurality of multi-channel optical add/drop multiplexers (OADMs) connected in parallel, said OADMs having drop and add ports connected to cross with each other, and

a switching unit for switching a number of channels in accordance with an operation control signal for each of the channels, wherein each of the multi-channel OADMs has drop and add ports, and wherein each OADM drops and adds optical signals by applying an electric field that produces an electro-optical (E/O) effect.

2. The WDM switch of claim 1, further comprising:

a number of inputs/outputs determined in accordance with a number of the multi-channel OADMs.

3. The WDM switch of claim 1, wherein the multi-channel OADMs comprise a plurality of 1-channel OADMs connected in series, each of the 1-channel OADMs dropping a corresponding channel signal from an input WDM optical signal, and adding the corresponding channel signal dropped by another multi-channel OADM in accordance with the operation control signal for each channel.

4. The WDM switch of claim 3, wherein each of the 1-channel OADMs comprises:

first and second conductors arranged periodically so as to have a pair of different polarities;

an optical waveguide-type coupler dropping or adding an optical signal of a specific channel by the electric field, which is generated from the first and second conductors;

a power supply unit supplying the second conductor with a power; and

a switch, located between the second conductor and power supply unit, to control the power supply of the second conductor, so as to control generation and termination of the electric field in accordance with the operation control signal.

5. The WDM switch of claim 4, wherein widths and interval of the first and second conductors are adjusted so as to change the channel to be dropped/added.

6. The WDM switch of claim 4, wherein a voltage of the power supply applied to the second conductor is adjusted in order to change the channel to be dropped/added.

7. The WDM switch of claim 4, wherein the optical waveguide-type coupler is formed from a material within which the electro-optical effect occurs, such that a refractive index is changed by the electric field.

25. The WDM switch of claim 1, wherein each OADM receives a separate wavelength division multiplexing (WDM) optical signal.

26. The WDM switch of claim 1, wherein each OADM outputs a separate wavelength division multiplexing (WDM) optical signal.

8. A multi-channel optical add/drop multiplexer (OADM) in a WDM system, comprising:

a plurality of 1-channel OADMs connected in series, each of the 1-channel OADMs dropping or adding different channel signals from an input WDM optical signal in accordance with operation control signals for the channels, respectively, wherein each OADM drops or adds a channel signal by applying an electric field which produces an electro-optical (E/O) effect.

9. The multi-channel OADM of claim 8, wherein the operation control signals are activated/deactivated for the corresponding channels so as to select a plurality of the channel signals to be dropped/added.

10. The multi-channel OADM of claim 8, wherein each of the 1-channel OADM comprises:

first and second conductors arranged periodically so as to have a pair of different polarities;

an optical waveguide-type coupler dropping or adding an optical signal of a specific channel by the electric field, which is generated from the first and second conductors;

a power supply unit supplying the second conductor with a power; and

a switch, located between the second conductor and power supply unit, to control a power supply of the second conductor, so as to control generation and termination of the electric field in accordance with the operation control signal.

11. The multi-channel OADM of claim 10, wherein widths and interval of the first and second conductors are adjusted so as to change the channel to be dropped/added.

12. The multi-channel OADM of claim 10, wherein a voltage of the power supply applied to the second conductor is adjusted so as to change the channel to be dropped/added.

13. The multi-channel OADM of claim 10, wherein the optical waveguide-type coupler is formed using a material which demonstrates the electro-optical effect which causes a refractive index to change when by the electric field is applied.

14. A 1-channel OADM in a WDM system, comprising:

first and second conductors arranged periodically so as to have a pair of different polarities;

an optical waveguide-type coupler dropping or adding an optical signal of a specific channel by an electric field generated from the first and second conductors;

a power supply unit supplying the second conductor with a power; and

a switch, located between the second conductor and power supply unit, to control a power supply of the second conductor so as to control generation and termination of the electric field in accordance with an operation control signal.

15. The 1-channel OADM of claim 14, wherein the first conductor is grounded.

16. The 1-channel OADM of claim 14, wherein widths and interval of the first and second conductors are adjusted so as to change the channel to be dropped/added.

17. The 1-channel OADM of claim 14, wherein a voltage of the power supply applied to the second conductor is adjusted so as to change a channel to be dropped/added.

18. The 1-channel OADM of claim 14, wherein the optical waveguide type coupler is formed using a material which demonstrates an electro-optical effect which causes a refractive index to change when the electric field is applied.

19. A method of controlling a 1-channel optical add/drop multiplexer (OADM) in a WDM system, comprising:

checking whether a drop/add operation is demanded or not;

forming an electric field at an optical waveguide-type coupler if the drop/add operation is demanded; and

carrying out the drop/add operation of a channel by the formed electric field.

20. The method of claim 19, wherein the step of forming the electric field at the optical waveguide type coupler is carried out by applying a ground voltage to one of conductors arranged periodically at the optical waveguide type coupler so as to have different polarities from each other, and applying a power supply voltage to the other conductor.

21. The method of claim 19, wherein the electric field formed at the optical waveguide-type coupler is terminated if the drop/add operation is not demanded.

22. A method of controlling a multi-channel optical add/drop multiplexer (OADM) in a WDM system, comprising:

checking channels to be dropped or added;

outputting operation control signals for activation to OADMs of the channels to be dropped or added, respectively; and

activating the OADMs to drop or add optical signals of the corresponding channels based on the operation control signals, wherein, when activated, each of the OADMs applies an electric field to a corresponding optical waveguide-type coupler to add or drop an optical signal to or from a corresponding one of the channels.

23. The method of claim 22, wherein the electric field applied by each of the OADMs changes a refractive index of a corresponding optical waveguide-type coupler.

24. A method of controlling a WDM switch, comprising:

checking channels to be switched to a different WDM network;

activating a first OADM to drop an optical signal from the channel to be switched and a second OADM to add the optical signal from the dropped channel, wherein when the first and second OADMs are activated, electric fields are applied to respective optical waveguide-type couplers which carry the optical signals; and

adding the channel dropped from the second OADM if the corresponding channel is dropped from the first OADM, so as to switch the corresponding channel to the different WDM network.