Alcatel-Lucent Unveils CMOS Optical Filter

Alcatel-Lucent announced today it has demonstrated what it says is the first CMOS silicon-based tunable optical waveguide equalizer, "a major step in the industry's drive toward sophisticated, high-density, low-cost silicon chip-based optical networking devices."

In a paper presented today at the OFC/NFOEC (Optical Fiber Communication Conference & Exposition and the National Fiber Optic Engineers Conference), being held this week in Anaheim, researchers from Alcatel-Lucent's Bell Labs in New Jersey described how they had developed a versatile guided-wave equalizing optical filter fabricated entirely in a CMOS manufacturing line -- the sort of technology that produces computer integrated circuits today.

They said this research will enable telecom providers to move from using specialized and large optical networking devices to a new generation of low-cost, mass-produced silicon chips that combine electronics and photonics in a single chip, opening the door to new optical networking architectures that could usher in new sorts of broadband deployments and applications. Possible new applications include low-cost, mass deployment of fiber-to-the-home; truly meshed optical networks that cleanly switch optical signals between different transmission formats; and the deployment of optical networking into places unapproachable by today's optical networking devices, such as over short-runs or in confined spaces.

This unique optical filter builds upon the revolutionary work by the EPIC (Electronic and Photonic Integrated Circuits) program, funded by DARPA and led by BAE Systems in partnership with MIT, Applied Wave Research and Bell Labs, through Alcatel-Lucent's LGS subsidiary. The EPIC program produced the first devices that embedded photonic filters, modulators and detectors with electronics onto the same silicon-based integrated circuit.

"The EPIC project achieved the critical first step in building the foundation for this new breed of devices," said Alice White, vice president, Enabling Physical Technologies Research at Alcatel-Lucent's Bell Labs. "We've applied our core competency in optics and expertise in chip design and telecommunications technology toward realizing the full potential of silicon-based optical networking by not only creating circuits that can carry optical signals, but providing the control to modify those signals, which is a much more sophisticated process."

The demonstration of the new tunable filter is a critical step in this field of research, Alcatel-Lucent said in a statement. "These filters will enable network operators to clean up the light pulses within a transmission channel on the silicon chip, either directly or by modifying the signal in anticipation of later distortion, and balance the power of different transmission channels. Such reconfigurable filters could significantly improve the speed, cost and performance of next-generation optical and high-speed data networks by supporting advanced modulation formats that transport more information over a longer distance.

This work could also enable devices that could be remotely reconfigured, simplifying large-scale optical network management or reconfiguration, it said. By simultaneously equalizing the signal intensity profile, compensating for dispersion and switching transmission formats, such agile devices can also help transform the network from a point-to-point architecture to a mesh topology.

While this work represents only a proof-of-concept demonstration (generally, available technologies are not expected for 3 to 5 years), combining such optical filters with on-chip electronic circuits can provide a commercially viable path to providing reconfigurable, low-cost, low-power-consumption devices that could fit into small-form-factor pluggable modules. These new devices are also ideal for dual-use applications in systems that route data over both electronic and optical networks -- depending on the most appropriate delivery and/or transport format, Alcatel-Lucent said.

"The key to this groundbreaking demonstration is a new control configuration that uses a single voltage to adjust the signal equalization and an innovative architecture to realize complex responses in a low-order filter. The result is a highly adaptable transmitter, which brings a very rich level of control to silicon-based optical networking," the company said.

The work was sponsored under DARPA's EPIC program, managed by Jagdeep Shah of the Microsystems Technology Office.

For more information, visit: www.alcatel-lucent.com