By Oleh J. Sniezko, Sudhesh Mysore, Charles Barker, Aurora Networks, Inc.
This paper presents a WDM technology for downstream HFC communication. The technology, trademarked as LcWDM™, is a dense wavelength division multiplexing (DWDM) technology based on an extension of the ITU-T Recommendation G694.11 to the optical O-Band (1260 to 1360 nm).
An order of magnitude decrease in wavelength spacing (as compared to CWDM) allows all LcWDM™ wavelengths to be within ±20 nm window about the nominal zero dispersion wavelength (λ0) of standard SMF-28 type fiber (ITU-T G.652). This greatly reduces chirp-induced CSO due to fiber dispersion and allows for longer fiber spans.
This paper describes the various fiber phenomena – both linear and nonlinear – that limit the fiber distance and the number of wavelengths that can be supported by the two technologies (CWDM and LcWDM™). Descriptions of the detailed testing of fiber nonlinearities and how they affect system performance as well as architectural applications of the LcWDM™ system is also presented.
The LcWDM™ system has been carefully engineered to ensure that the fiber dispersion and nonlinearities of a typical (SMF-28) fiber, prevalent in HFC optical node links, do not degrade the link performance below the acceptable levels.