ITU-T covers all spectral bands: O to L

At the October 2001 meeting of the International Telecommunication Union Standardization Sector (ITU-T) Study Group 15 in Geneva, Working Party 4/15 reached agreements that will expand standards to cover operation in all the available recently defined spectral bands from 1260 to 1625 nm. Here are some of the actions taken to fully utilize this spectrum:

  • Agreed to develop a new Recommendation, provisionally designated G.cwdm, which will define a wavelength grid for coarse WDM applications. Provisional agreement was reached on a channel spacing of 20 nm, with the grid spanning the O-, E-, S-, C- and L-bands. The intent is to reach consent on G.cwdm at this May's meeting.
  • Agreed on channel-spacing boundaries in ITU-T Recommendation G.671 to delineate coarse, dense, and wide WDM applications as follows: dense WDM (DWDM), <1,000-GHz channel spacing; coarse WDM (CWDM), <50-nm channel spacing; and wide WDM (WWDM), >50-nm channel spacing.
  • Acknowledged the need to develop interface specifications for WDM applications utilizing the S- and L-bands and the concurrent need to augment the specifications of fiber characteristics in these bands.

Significant progress in other areas included:

  • Consent by Study Group 15 on new Recommendation G.693, providing optical system interface specifications for single-channel intra-office applications at 10 Gbits/sec and 40 Gbits/sec with target distances of up to 2 km.
  • Agreement to begin the development of specifications for long-haul DWDM applications at 40 Gbit/sec using return-to-zero coding formats for inclusion in revised ITU-T Recommendation G.959.1
  • Agreement to revise ITU-T Recommendation G.664 on optical safety procedures and requirements for optical transport systems to align with IEC documents and address safety aspects of distributed Raman amplification techniques.

Further progress is expected to be made at interim meetings of Questions 16 and 17/15 scheduled for next month in Bern, Switzerland.

Jerry Shrimpton represents Ciena Corp. in fiber-optic system physical-layer standards work in ITU-T Study Group 15 and chaired Question 16/15 at the October 2001 meeting of ITU-T Working Party 4/15 as Acting Rapporteur. He can be contacted at tel: 303-674-0981, fax: 303-674-0982; and e-mail:

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