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Laser Epiwafer Technology Plans to Develop Ultra-High-Efficiency Optical Interconnects

Epiwafer foundry and substrate maker IQE plc of Cardiff, Wales, UK says that its laser epiwafer technology has been employed to develop ultra-high-efficiency optical interconnects, as reported in two technical papers presented by Germany's Technische Universit?t (TU) Berlin at Photonics West 2014 in San Francisco (2-6 February).

Vertical-cavity surface-emitting laser (VCSEL) wafers, manufactured at IQE's Cardiff facility, were used by researchers at TU-Berlin to produce high-performance communications lasers that achieved error-free operation at speeds up to 40Gb/s with record low energy consumption. The VCSELs also demonstrated extreme temperature stability during high-speed operation up to 85°C.

It is widely recognised that the expanding growth in data communications is rapidly approaching a serious bottleneck as demand for higher performance battles with the need to reduce power consumption, particularly in increasingly large data centers, notes IQE.

This is driving the move from copper cables to optical fiber communications, which is essential in enabling the transmission of the high data volumes demanded from cloud computing, big data and the Internet of Things, the firm adds. Furthermore, the efficiencies achieved with VCSELs is a critical factor in reducing the overall energy consumption of optical interconnects used in data centers.

"Today's energy-hungry data centers are increasingly co-located alongside major industrial power plants," notes IQE's president & CEO Dr Drew Nelson. "Data volumes are forecast to continue growing and, with more than 20 billion devices being interconnected by 2020, the energy demand is rapidly becoming unsustainable," he adds. "Data centers are already early adopters of VCSEL technology to help reduce energy demand and are likely to continue to drive the trend for optical communications for industrial and commercial applications."

"Error-free operation of 850nm VCSELs at 25Gb/s was achieved with record-low dissipated energy of 56fJ/bit," says professor Dieter Bimberg, head of the Solid State Physics Institute at TU-Berlin. "This is the lowest reported value of dissipated energy at error-free operation for any semiconductor laser diode at any wavelength or bit rate. This result is achieved at a low current density of 10kA/cm2, demonstrating the suitability of our devices for application in reliable and sustainable commercial optical interconnects," he adds. "At 40Gb/s the IQE/TU-Berlin VCSELs dissipate only 108fJ per transmitted bit, which is at least four times less than any other published result for semiconductor laser diodes."

Further work also presented at Photonics West reported on high-efficiency operation of IQE's VCSEL materials carried out by TU-Berlin in collaboration with the Photonics Modelling Group at the Institute of Physics, Technical University of Lodz, Poland.

The presented papers resulted in Philip Moser and his team at TU-Berlin being presented with the SPIE Green Photonics Award for Communications 2014. 

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IQE's Vcsel Epiwafers Used by Tu-Berlin for Record Power Efficiencies in Optical Interconnects