WDM ring transmission system having reduced adjacent channel cross-talk

• US 6,021,233 A
• Filed: 02/12/1998
• Issued: 02/01/2000
• Est. Priority Date: 02/12/1998
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Koehler, Steffen D.
• Primary Examiner(s): Palmer, Phan T. H.
• Application Number:
  US09/024,370
• Time in Patent Office: 719 Days
• Field of Search: 385/24, 385/14, 385/2, 385/4, 385/8, 385/9, 385/10, 385/32, 385/37, 359/115, 359/118, 359/119, 359/124, 359/127, 359/128, 359/132, 359/133, 359/130
• US Class Current: 385/24
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/0283 WDM ring architectures

Abstract

A WDM ring configuration having reduced adjacent channel cross-talk is disclosed. In the WDM ring, an add/drop element having a filter for selecting an optical signal at a desired wavelength is spaced from another add/drop element having a filter adding an optical signal at an adjacent wavelength within a channel plan by at least one add/drop element that adds/drops an optical signal at a wavelength which is not next to either the optical signal at the desired wavelength or the adjacent wavelength.

Claims

1. An optical communication apparatus, comprising:

a plurality of optical emitters, each supplying a corresponding one of a plurality of optical signals, each of said optical signals being at a respective one of a plurality of wavelengths, said plurality of wavelengths conforming to a channel plan whereby said plurality of wavelengths successively increase from a lowest wavelength to a highest wavelength, said plurality of wavelengths including said lowest and highest wavelengths;

a first plurality of optical add/drop elements respectively coupled to corresponding ones of said plurality of optical emitters and configured to be coupled to an optical communication path, said first plurality of optical add/drop elements supplying said plurality of optical signals to said optical communication path; and

a second plurality of optical add/drop elements configured to be coupled to said optical communication path, one of said second plurality of optical add/drop elements selecting a first one of said plurality of optical signals at a first one of said plurality of wavelengths, said one of said second plurality of optical add/drop elements being provided adjacent one of said first plurality of optical add/drop elements coupled to one of said plurality of optical emitters supplying a second one of said plurality of optical signals at a second one of said plurality of wavelengths, said second one of said plurality of wavelengths being spaced from said first one of said plurality of wavelengths by at least one wavelength in said channel plan.

2. An optical communication apparatus in accordance with claim 1, further comprising:

a plurality of additional optical emitters, each of which being coupled to a respective one of said second plurality of optical add/drop elements, and each supplying a corresponding one of said plurality of optical signals to said optical communication path via said respective one of said second plurality of optical add/drop elements; and

a plurality of optical receivers, each of which being coupled to a respective one of said first and second pluralities of optical add/drop elements, each of a first group of said plurality of optical receivers being coupled to a respective one of said first plurality of optical add/drop elements, and each of a second group of said plurality of optical receivers being coupled to a respective one of said second plurality of optical add/drop elements.

3. An optical communication apparatus in accordance with claim 1, further comprising an optical receiver coupled to said second one of said second plurality of optical add/drop elements.

4. An optical communication apparatus in accordance with claim 1, wherein each of said first and second pluralities of optical add/drop elements comprises a filtering element.

5. An optical communication apparatus in accordance with claim 1, wherein a plurality of optical receivers are respectively coupled to each of said second plurality of optical add/drop elements.

6. An optical communication apparatus in accordance with claim 1, wherein said optical communication path has a ring configuration.

7. An optical communication apparatus in accordance with claim 1, wherein each of said first plurality of optical add/drop elements is substantially colocated in a central hub.

8. An optical communication apparatus, comprising:

a plurality of optical emitters, each supplying a corresponding one of a plurality of optical signals, each of said optical signals being at a respective one of a plurality of wavelengths, said plurality of wavelengths conforming to a channel plan whereby said plurality of wavelengths successively increase from a lowest wavelength to a highest wavelength, said lowest and highest wavelengths being included in said plurality of wavelengths;

a plurality of optical add/drop elements, each of a first subgroup of said plurality of add/drop elements respectively coupled to corresponding ones of said plurality of optical emitters and configured to be coupled to an optical communication path, said first subgroup of said plurality of optical add/drop elements supplying said plurality of optical signals to said optical communication path, each of a second subgroup of said plurality of add/drop elements respectively selecting one of said plurality of optical signals from said optical communication path, and being spaced, along said optical path, from one of said first subgroup of add/drop elements coupled to one of said plurality of optical emitters supplying another one of said plurality of optical signals at one of said plurality of wavelengths in said channel plan adjacent a wavelength of said one of said plurality of optical signals by at least one of said optical add/drop elements; and

a plurality of optical receivers, each of which being respectively coupled to one of said second subgroup of said add/drop elements.

9. An optical communication apparatus in accordance with claim 8, wherein said first subgroup of said plurality of optical add/drop elements further select a corresponding one of said plurality of optical signals, said optical communication apparatus further comprising:

a plurality of additional optical receivers, each of which being coupled to a respective one of said first subgroup of said plurality of optical add/drop elements, and respectively receiving one of said plurality of optical signals from said first subgroup of said plurality of optical add/drop elements; and

a plurality of additional optical emitters, each of which being coupled to a respective one of said second subgroup of said plurality of optical add/drop elements, each of said plurality of additional optical emitters supplying a corresponding one of said plurality of optical signals to said optical communication path via said respective one of said second subgroup of said plurality of optical add/drop elements.

10. An optical communication apparatus in accordance with claim 8, wherein each of said plurality of add/drop elements comprises a filtering element.

11. An optical communication apparatus in accordance with claim 8, wherein each of said first subgroup of said plurality of optical add/drop elements is substantially colocated in a central hub.

12. A method for allocating a plurality of optical add/drop elements along a closed optical communication path, said optical communication path being configured to carry a plurality of optical signals, each at a respective one of a plurality of wavelengths, each of said plurality of wavelengths conforming to a channel plan, a first group of said plurality of optical add/drop elements, each being configured to add and drop a respective one of said plurality of optical signals, and a second group of said plurality of optical add/drop elements, each being configured to add and drop a corresponding one of said plurality of optical signals, said method comprising the steps of:

partitioning said closed optical communication path into first and second sections;

subdividing said first section of said closed optical communication path into a plurality of first subsections;

subdividing said second section of said optical communication path into a plurality of second subsections;

coupling each of said first group of said plurality of add/drop elements to a respective one of said first subsections, successive ones of said coupled first group of said plurality of add/drop elements being respectively configured to add and drop one of said plurality of optical signals at a successive one of said plurality of wavelengths within said channel plan; and

coupling each of said second group of said plurality of add/drop elements to a respective one of said second subsections.

13. A method in accordance with claim 12, wherein successive ones of said second group of said plurality of add/drop elements along said second section of said closed optical communication path are respectively configured to add and drop one of said plurality of optical signals at a successive one of said plurality of wavelengths within said channel plan.

14. A method in accordance with claim 12, wherein said step of coupling each of said second group of said plurality of add/drop elements further comprises the step of coupling one of said second group of said plurality of add/drop elements to one of said second subsections lying opposite one of said first subsections, said one of said second group of said plurality of add/drop elements and one of said first group of said plurality of add/drop elements coupled to said one of said first subsections being configured to add and drop optical signals at the same one of said plurality of wavelengths.

15. A method of allocating a plurality of optical add/drop elements along an optical communication path, said optical communication path being configured to carry a plurality of optical signals, each at a respective one of a plurality of wavelengths, each of said plurality of wavelengths conforming to a channel plan, a first group of said plurality of optical add/drop elements, each being configured to add and drop a respective one of said plurality of optical signals, and a second group of said plurality of optical add/drop elements, each being configured to add and drop a corresponding one of said plurality of optical signals, said method comprising the steps of:

partitioning said optical communication path into first and second sections;

subdividing said first section of said optical communication path into first N subsections, where N is an integer at least equal to three;

subdividing said second section of said optical communication path into second N subsections;

coupling each of a first group of said plurality of optical add/drop elements to a respective one of said first N subsections, successive ones of said coupled first group of said plurality of add/drop elements being configured to add and drop a respective one of a group of said plurality of optical signals at successive ones of said plurality of wavelengths in said channel plan; and

coupling each of a second group of said plurality of optical add/drop elements to a respective one of said second N subsections.

16. A method in accordance with claim 15, wherein successive ones of said coupled second group of said plurality of add/drop elements being configured to add and drop a respective one of another group of said plurality of optical signals at said successive ones of said plurality of wavelengths in said channel plan.

17. A method in accordance with claim 15, wherein said step of coupling each of said second group of said plurality of add/drop elements further comprises the step of coupling one of said second group of said plurality of add/drop elements to one of said second subsections lying opposite one of said first subsections, said one of said second group of said plurality of add/drop elements and one of said first group of said plurality of add/drop elements coupled to said one of said first subsections being configured to add and drop optical signals at the same one of said plurality of wavelengths.

18. A method in accordance with claim 15, further comprising the steps of:

coupling each of a third group of said plurality of optical add/drop elements to a respective one of said first N subsections, successive ones of said coupled third group of said plurality of add/drop elements being configured to add and drop a respective one of another group of said plurality of optical signals at additional successive ones of said plurality of wavelengths in said channel plan; and

coupling each of a fourth group of said plurality of optical add/drop elements to a respective one of said second N subsections.

19. A method in accordance with claim 18, further comprising the steps of:

coupling each of a third group of said plurality of optical add/drop elements to a respective one of M ones of said first N subsections, M being an integer less than N, successive ones of said coupled third group of said plurality of add/drop elements being configured to add and drop a respective one of an additional group of said plurality of optical signals at further ones of said plurality of wavelengths in said channel plan; and

coupling each of a fourth group of said plurality of optical add/drop elements to a respective one of M ones of said second N subsections.