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posted by Dopefish on Thursday February 27 2014, @09:00AM   Printer-friendly
from the super-fast-downloads-of-animated-gifs dept.
visaris writes " reports researchers at IBM have set a new record for data transmission over a multi-mode optical fiber. The record data rate of 64Gb/s was achieved over a cable 57 meters long, using non-return-to-zero (NRZ) modulation with a type of laser called a vertical-cavity surface-emitting laser (VCSEL). Researcher Dan Kuchta notes, "Others have thought that this modulation wouldn't allow for transfer rates much faster than 32 Gb/s." Indeed, many researchers thought that achieving higher transmission rates would require turning to more complex types of modulation, such as pulse-amplitude modulation-4 (PAM-4). The achievement demonstrates that standard, existing technology for sending data over short distances should be able to meet the growing needs of servers, data centers and supercomputers through the end of this decade, according to the researchers. "What we're showing is that [...] this technology has at least one or two more generations of product life in it," says Kuchta."
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  • (Score: 3, Informative) by TheRaven on Friday February 28 2014, @09:23AM

    by TheRaven (270) on Friday February 28 2014, @09:23AM (#8385) Journal
    As the other poster said, the latency over the fibre is not the limit. Unless you have an optical processor, at both ends you need to convert the optical signal into an electronic one. This adds a fairly noticeable amount of latency, typically more than using an electrical signal over the length for short runs. This gets significantly worse when you have a switched network, rather than a point-to-point connection, because the switches are also electrical (there are some research prototypes of purely optical hubs, but nothing in production that I'm aware of), so every switch involves an optical-electronic-optical conversion, plus the switching / buffering time. This can add up to several ms, which can completely offset the improvement in bandwidth for anything remotely synchronous.
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