- Bandwidth Reigns at Fiber Conference
Stephanie A. Weiss
Multiwavelength and high-speed optical fiber transmission technologies, particularly those aimed at metropolitan communications networks, converged on the exhibit floor at the Optical Fiber Communications Conference in February.
The conference and exhibit, sponsored by the Optical Society of America, largely reflected experts' consensus that future data- and telecommunications systems will use some combination of wavelength division and time division multiplexing (see Photonics Spectra, February 1999, p. 96).
As an example of the technology convergence, Nortel, the leader in high-speed networking, announced dense wavelength division multiplexing components as Alcatel, a leader in multiwavelength networking, demonstrated a 40-Gb/s network that officials predicted would be commercially available by the third or fourth quarter of 2000.
Alcatel was alone in demonstrating a 40-Gb/s transmission system during the show, but several companies offered 40- Gb/s components and many had 10-Gb/s components and systems. Exhibitors said early implementers have proved the 10- Gb/s technology, so it is becoming ubiquitous as a means of increasing bandwidth without increasing system footprint.
On the wavelength multiplexing side, many exhibitors offered commercial transmitters, amplifiers and other equipment to accommodate wavelengths in the L-band, a spectral region on the International Telecommunications Union grid just beyond the traditional 1550-nm C-band. In addition, Lucent Technologies demonstrated a multiwavelength application of its AllWave optical fiber, which opens up a wavelength band around 1400 nm -- but this will work only for those who install the special fiber.
The new wavelength bands are interesting because they allow network providers to add channels to wavelength division multiplexing systems without reducing the channel spacing. Commercial communications networks generally operate on a 100-GHz channel grid (that is, wavelengths spaced about every 0.8 nm). Reducing channel spacing increases the wavelength accuracy requirements (and costs) of laser transmitters.
Nevertheless, bandwidth requirements may yet require higher channel densities. At the exhibit, several tunable and fixed laser options aimed to fulfill those needs, and several test equipment manufacturers offered products that measure those new devices' wavelengths to within 50 or 25 GHz.
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