A new record has been set for short-range data transmission that proves the existing technology remains up to snuff. Researchers at IBM have discovered that the standard technology for sending data over short distances — via a multimode optical fiber and a vertical-cavity surface-emitting laser (VCSEL) — should continue to meet the growing needs of servers, data centers and supercomputers at least through the end of this decade. “This technology has at least one or two more generations of product life in it," said Dan Kuchta, a researcher with the IBM T.J. Watson Research Center. To send the data, the researchers used standard non-return-to-zero (NRZ) modulation, which many have thought would not allow transfer rates faster than 32 Gb/s. Kuchta said a common belief is that achieving higher transmission rates would require a more complex modulation, such as pulse-amplitude modulation-4 (PAM-4). However, the researchers attained a rate that is about 14 percent faster than before by sending data at 64 Gb/s over a 57-m-long cable using the VCSEL. They also used custom silicon-germanium chips developed at IBM Research. “The receiver chip is a unique design that simultaneously achieves speeds and sensitivities well beyond today’s commercial offerings,” Kuchta said. “The driver chip incorporates transmit equalization, which widens the bandwidth of the optical link.” The fast speeds recorded worked only on 57-m-long cable, so the technology is not designed to send data over long distances. It is most suitable for transmitting data within a building, the researchers said, noting that about 80 percent of such cables are less than 50 m. For more information, visit www.ibm.com.