October 20, 2006, Ewing, NJ--Discovery Semiconductors--manufacturers of ultrafast InGaAs photodetectors and custom products for applications ranging from analog RF links to ultrafast digital communications--has provided 25-GHz multimode photodiodes to the Technical University of Berlin for their research on directly modulated 980-nm lasers.
Prof. D. Bimberg, with the Technical University of Berlin, led a collaborative group of researchers from the Center for Nano Photonics, Nanosemiconductor GmbH in Dortmund and Fraunhofer Institute HHI in Berlin, Germany. They recently reported the development of directly modulated, submonolayer grown quantum dot vertical-cavity surface-emitting lasers (VCSELs) at 980 nm for 20 Gb/s error-free operation at 85 °C. The lasers were characterized and tested using a Discovery DSC30S multimode photodiode; 25 GHz photodiode coupled to a 62.5 μm graded index multimode fiber.
"Next generation short distance optical networks like chip-to-chip, or backplane applications require temperature robust ultra-high bit rate sources," Bimberg said. "Our final goal is a 1 Tbit/s VCSEL array fitting the Terabus demands of IBM, INTEL, Cisco, etc. We were able to characterize the high speed performance of the multimode laser without the detector compromising the results."
Roy Howard, the applications engineer at Discovery who witnessed the development of the multimode high speed photodiodes over the last six years, noted that the ease of optically interfacing the large aperture fibers into an experiment and the broad wavelength coverage of Discovery's photodiodes have opened up a number of new applications for high bit rate multimode devices.
"The development of directly modulated VCSEL lasers at 980 nm is an important milestone on the road to 20 and 40 Gb/s multimode transmission," he said, adding that Discovery is seeing a marked increase in business for multimode fibered optical receivers at data rates above 10 Gb/s and that the need for technical solutions for 100 Gb/s Ethernet is one of the major drivers for this growth.