Professor Anders Larsson has been awarded an HP Labs Innovation Research Award for work on “High Contrast Grating VCSELs for WDM Computer Interconnects” in collaboration with Dr. Michael Tan and his group at the Intelligent Infrastructure Lab at HP Labs. The project involves the Chalmers researchers Johan Gustafsson, Åsa Haglund, Jörgen Bengtsson and Erik Haglund. The HP Labs' Innovation Research Program is designed to create opportunities at colleges, universities and research institutes around the world for collaborative research with HP. Anders Larssons is one out of 61 university professors selected for the prestigious HP Labs Innovation Research Awards in 2012.

Reserachers involved in the project Jörgen Bengtsson, Erik Haglund, Anders Larsson, Johan Gustafsson and Åsa Haglund. Photography: Peter Widing
High Contrast Grating VCSELs for WDM Computer Interconnects
The vertical cavity surface emitting laser (VCSEL) is the primary light source for short-reach optical communication because of high efficiency, excellent high speed properties, efficient coupling to optical fibers, and low manufacturing cost. It is today produced in large volumes for high capacity optical interconnect cables in storage area networks (datacenters) and high performance computing systems (computer clusters, supercomputers). In the near future, high speed optical cables with VCSEL-based optical transmitters will also make their debut in consumer electronics (Thunderbolt, USB, HDMI, etc.).
For computing applications, the small footprint and high modulation speed of VCSELs enable very high density and very high capacity interconnects. To increase capacity beyond what can be provided by a single channel, space division multiplexing (parallel fiber ribbons or multicore fibers) or wavelength division multiplexing (WDM) can be used. WDM, which requires monolithic multi-wavelength VCSEL arrays, enables optical interconnect architectures which offer more complex interconnect topologies and routing schemes. It also enables the interconnect network to adapt to irregular and time varying traffic patterns.
The project aims to develop a VCSEL technology whereby the wavelength of individual VCSELs can be set in a post-growth fabrication process, thereby enabling the realization of low power consumption, high speed, multi-wavelength VCSEL arrays for future WDM interconnects in computing systems.
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