Multiwavelength laser slashes DWDM inventories

By Tami Freeman

Widespread availability of efficient, low-cost multiwavelength laser sources could well stimulate the migration of DWDM technology from the long haul into metro and access networks. With this in mind, Canadian photonic subsystem specialist Peleton has come up with a laser that can simultaneously generate up to 160 wavelengths across the L-, C- and S-bands.

Traditional DWDM platforms use a bank of individual lasers - each with their own associated control electronics and cooling, wavelength-locking and packaging requirements - to produce multiple wavelengths simultaneously. Peleton's new laser source provides an intriguing alternative, one that reduces the number of active components dramatically.

"For a typical application, we can demonstrate a 50% reduction in cost-per-wavelength versus single-laser sources," claimed Robert Taylor, the firm's vice-president of marketing. "And compared with existing source banks, Peleton can offer a 40-channel solution at one-twentieth of the size."

Peleton's multiwavelength laser source (MWLS) works by taking a single-wavelength output from a distributed-feedback (DFB) laser seed and feeding it into a nonlinear fibre medium. By controlling the optical input conditions and the fibre's dispersion characteristics, the firm can exploit nonlinear optical processes to create a wavelength-multiplication effect.

The resulting multiwavelength signal then feeds into a "personality module", which tailors the final output for individual applications: flattening all the channels to a constant level, changing the relative power levels or even blocking wavelength bands as required. The power level produced by the MWLS is comparable to that produced by traditional DWDM DFB-based sources after they have been multiplexed together.

"Peleton can control the band of operation as well as the spacing of the individual wavelengths," said Taylor. "We also employ a proprietary locking technique to ensure that all the wavelengths are simultaneously aligned to the standard ITU grid spacing. This is the first commercially viable multiwavelength technology platform."

Taylor added that the MWLS can provide a channel spacing of 100, 50 or 25 GHz, while other multiwavelength lasers on the market today offer far smaller channel spacing with a greatly reduced wavelength band. "There are no applications that use their channel spacing and they are not full-band," he claimed.

Peleton is currently trialling a 40-channel C-band device. Taylor adds that no additional components are required to generate an 80- or 160-wavelength version, though the release of such products will be driven by market demand.

• This article originally appeared in FibreSystems Europe in association with LIGHTWAVE Europe April 2004 p7.