IBM multimode fiber sets new records for short-range transmission rates

According to IBM, the company's researchers have set new records
for data transmission speeds in multimode fiber.
Multimode fiber is a cable
typically used to connect adjacent computers within a single building or campus.
The research results suggest that standards and existing technologies for transmitting data over short distances should be able to meet the growing market demand
for servers, data centers and supercomputers within a decade.
Based on a VCSEL (vertical-cavity surface-emitting laser) laser with a 57-meter cable, the researchers achieved a transmission rate
of 64 Gb/s.
It is 14% faster than the previous record and 2.
5 times
faster than current typical commercial technology.

To send the data, the researchers used standard non-return-to-zero (NRZ) code modulation
.
According to Dan Kuchta, a researcher at the IBM TJ Watson Research Center in New York, NRZ modulation does not exceed the transmission speed
of 32Gb/s.
Many researchers believe that achieving higher transmission rates requires resorting to more complex modulation types, such as pulse-amplitude modulation4 (PAM-4, pulse-amplitude modulation-4).

However, because Kuchta and his colleagues achieved faster transmission speeds with NRZ modulation, the NRZ technology has at least one or two product cycles
left.
Kuchta will present the results of these findings
at the Optical Fiber Communication Conference & Exhibition 2014 at the Moscone Exhibition Center in San Francisco, California, March 9-13 。 His presentation was "64Gb/s Transmission over 57m MMF using an NRZ Modulated 850nm VCSEL"
.

To achieve high speed, the researchers used VCSEL lasers developed by Chalmers University of Technology in Sweden and IBM Research Center to develop custom silicon germanium (SiGe) chips
.
Kuchta said the design of the receiver chip is unique
.
It surpasses current commercial products
in terms of speed and sensitivity at the same time.
The driver chip widens the optical link bandwidth
through transmission equalization technology.
Although this method is very typical in the field of electrical communications, it is relatively new
in the field of optical communications.

This fast transmission speed can only reach a distance of 57 meters, so the technology is not suitable for sending data
across continents.
It is best suited for transferring data
within buildings.
About 80 percent of the cables in data centers, and most cables used in typical supercomputers
, are within 50 meters.
At present, this new technology is now ready for commercial use
.