Researchers at the University of California, Santa Barbara (UCSB) have made an important step towards eliminating optical-electrical-optical (OEO) conversion stages in router hardware.
Steve Nicholes and Milan Mašanović have developed what they claim is the world's first monolithic tunable optical router on a single indium-phosphide (InP) chip, and demonstrated error-free operation at 40 Gbit/s per channel.
The 4.25 mm x 14.5 mm device integrates eight tunable wavelength converters together with an arrayed waveguide grating router (AWGR), which are used to direct packets through the router according to their wavelength.
Each tunable wavelength converter is highly complex, comprising a sampled-grated DBR laser, semiconductor optical amplifiers, passive phase shifters, an integrated differential delay line, multimode interferometer and variable optical attenuators. In total the complete chip requires the integration of more than 200 functional elements.
The team's ultimate goal is to shrink the size of state-of-the-art internet routers that occupy a full 7-foot equipment rack today down to a single linecard.
This will require pushing the boundaries of how many optical devices can be integrated onto a single chip. An eight-channel router is an impressive first step but project leader Dan Blumenthal already has his eye on 64-channel optical routers.
"The key is using 4-inch, and hopefully some day larger, indium phosphide or migrating to the new hybrid silicon platforms that are coming out," he commented.
"The larger wafers will be needed to get multiple devices this size, then of course the yield, ways to test and package, would all need to be worked out."
The monolithic tunable optical router, or MOTOR, is a product of a project called LASOR in which Blumenthal is principal investigator.
Standing for "Label-switched optical router", LASOR is an approximately $18 million element of umbrella project, called Data in Optical Domain-Network (DOD-N), which is funded by the DARPA Microsystems Technology Office.
The LASOR project has been running since 2004 and is just finishing its Phase II work, with a 12-month duration Phase III stage already confirmed.
• Want to know more on this topic? In the May issue of FibreSystems Europe magazine, Leontios Stampoulidis and Efstratios Kehayas from the National Technical University of Athens will discuss the enabling technologies for building an all-optical label-switched router, and the goals of the European project ICT-BOOM. Subscribe now to reserve your copy.