A new record for data transfer speed

The researchers were able to transfer data at a rate of 64 gigabit per second (Gb/s64) through a cable 57 meters long using a special type of laser known as a "Vertical Hole Surface Emission Laser"

Researchers have set a new record for the speed of data transfer through multimode optical fiber, a type of cable commonly used to link adjacent computers located in a single building or complex. The achievement proves that the usual and existing technology for transmitting data over short distances will be able to meet the growing demands of servers, data centers and supercomputers until the end of the current decade, the researchers claim.

Researchers from IBM have set a new record for the speed of data transfer through multi-mode optical fiber, a type of cable commonly used to link adjacent computers located in a single building or complex. The researchers were able to transfer data at a rate of 64 gigabit per second (Gb/s64) through a 57 meter long cable using a special type of laser known as a "vertical hole surface emission laser" (VCSEL), where this rate is 14% faster From the previous speed record and 2.5 times faster than the capabilities inherent in the normal commercial technology available in the market today.

To transmit the data, the researchers used standard non-return-to-zero (NRZ) modulation. "Other researchers thought that this type of modulation would not allow transfer rates faster than 32 Gb/s," said researcher Dan Kuchta of IBM, at the research center in New York. Many researchers believed that achieving higher transmission rates would require the use of more complex types of modulation, for example - pulse-amplitude modulation-4 (PAM-4). "What we demonstrated is that this is absolutely not the case," explains the researcher. "In this technology lie one or two more generations of product life."

In order to achieve such high speeds, the researchers used VCSEL type lasers developed at Chalmers University in Sweden and silicon-germanium chips developed at the IBM Research Center. "The receiver chip has a unique design that simultaneously achieves speeds and sensitivities that are higher than the performance available today," explains the researcher. "The drive chip includes a transmission comparator that expands the bandwidth of the optical connection. "Despite the fact that this method was commonly used in the past in electronic communication, it has not yet become accepted in optical communication," notes the researcher.

"Researchers usually base themselves on a rule of thumb that states that the practical information transfer rate will be about 1.7 times the bandwidth," explains the researcher. "This means that with the help of our laser (VCSEL), which has a bandwidth of 26 gigahertz, the rate should be only 44 Gb/s." "What we do with the help of the equation is that we were able to break this historical rule of thumb," explains the researcher. These high speeds are only maintained for a distance of 57 meters, so this technology is not intended for transferring data between countries or continents. Instead, it is best suited for transferring data within a single building, says the researcher. About 80% of cables in data centers and most, if not all, cables used in conventional supercomputers are less than 50 meters in length. The technology, the researcher points out, is ready for commercialization right now.

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