Over several short years, Coarse Wavelength Division Multiplexing (CWDM) has gone from a proposal, which laid out the motivation and technical roadmap [1], to an ITU standard [2], to a commercially deployed technology with dozens of equipment makers producing components, subsystems and optical network solutions. The emergence of CWDM as a viable optical networking technology coincides with the trend among service providers to push optical networking capabilities beyond the core transport network out closer to the end users, where costs become increasingly important. CWDM is generally viewed as a less expensive alternative to dense wavelength division multiplexing (DWDM) due to the much larger channel spacing for CWDM systems (20 nm as compared to 0.4 nm – 1.6 nm for DWDM). Such relaxed specifications on channel spacing permit the use of lower cost uncooled, unstabilized, and directly modulated laser transmitters as well as inexpensive passive WDM components. CWDM also has the potential for true plug-and-play systems with pluggable CWDM transceivers at distinct wavelengths incorporated into different vendors' gear. This approach would, for example, permit the consolidation of diverse optical services onto common line fibers. Of course, along with this approach come limitations: the CWDM standard defines a maximum of 18 channels from 1270 nm to 1610 nm, however the current vendors' emphasis is on 4 or 8 channels systems centered around 1550 nm to minimize fiber loss and to avoid the 1380-nm water peak present in most deployed fiber. Not only does this channel plan have the obvious limitation of reduced capacity relative to DWDM systems, but the wide band of operation (153 nm for an 8-channel system) makes amplification with widely available erbium-doped fiber. amplifiers (EDFA) impossible. The loss budgets for these unamplified systems, which are determined solely by the transmitter power and receiver sensitivity, are typically around 30 dB for 2.5-Gb/s channels. This paper will address the prospects for mitigating the loss limit through the use of optical amplifiers, while maintaining the theme of cost effectiveness. a) Gain versus wavelength for the LOA used in [3] for total input powers ranging from −20 dBm to +3 dBm. b) Input (inset) and output spectra for the upgraded system with 8 × 2.5 Gb/s DWDM channels in the 1550-nm band.
Abstract:
This paper addresses the prospects for mitigating the loss limit of amplified coarse wavelength division multiplexing (CWDM) through the use of optical amplifiers, while ...Show MoreMetadata
Abstract:
This paper addresses the prospects for mitigating the loss limit of amplified coarse wavelength division multiplexing (CWDM) through the use of optical amplifiers, while maintaining the theme of cost effectiveness.
Published in: The 16th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 2003. LEOS 2003.
Date of Conference: 27-28 October 2003
Date Added to IEEE Xplore: 08 January 2004
Print ISBN:0-7803-7888-1
Print ISSN: 1092-8081