The researchers are working on a cabling system that can provide data transfer speeds several times faster than existing USB connections using an extremely thin polymer cable, in a system that echoes the path of the Thunderbolt project.
Presented at the IEEE International Solid-State Circuits Conference in February, the research aims to develop a type of connection that offers much better connectivity than current methods. In part, the goal is to achieve this by replacing the copper wiring with another one.
Copper is typically used for cables like USB and HDMI to handle data transfers, but it requires a lot of power to operate at high levels of data transmission. “There is a fundamental trade-off between the amount of energy burned and the rate of information exchanged,” said Jack Holloway, a former MIT student and lead author.
Although “increasingly bulky and expensive” copper can be replaced with fiber optic cables, this presents its own problems. Since silicon chips have a hard time dealing with photons, this makes optimizing the interconnection between the cable and computers more difficult.
According to Holloway, “there are all kinds of expensive and complex integration schemes, but from an economic perspective, it is not a great solution”, which led developers to create their own version.
Combining the benefits of copper and optical fiber conduits, a plastic polymer is used by researchers. This makes manufacturing cheaper than copper wires, which could be an attractive proposition for cable producers.
The polymer can also use subterahertz electromagnetic signals, which are more energy efficient than copper at high data loads. This efficiency is believed to approximate that of fiber optic systems, but crucially with better compatibility with silicon chips.
The low-cost chips are paired with the polymer conduit which can generate the high frequency signals powerful enough to transmit directly to the conduit. As such, it is expected that the system will be manufactured using standard methods, which also makes its production economical.
The cables themselves can also be extremely thin, with the cross-sectional area of the interconnect measuring 0.4mm by a quarter of a millimeter, smaller than typical copper variants.
This small, hair-like cable can be used to carry data on three different parallel channels, enabling a total bandwidth of 105 gigabits per second to be achieved. Conduit bundling can place cables in the terabit range per second, but still at a reasonable cost.
Echoes of Thunderbolt
The system, using chips at each end of a cable, uses a concept relatively similar to Thunderbolt cables, although with a different conduit in use. In each case, the chips inside the cable are used to manage the data being fed into the cable at one end and out of the other, while also interfacing with the conduit itself.
It seems plausible that such a system could be employed for a future Thunderbolt-style connection, allowing it to go well beyond the current upper limit of 40 Gbps.
Another connection with Thunderbolt is research funding. Although Thunderbolt was developed by Intel and Apple, unnamed polymer research was also funded by Intel, along with Raytheon, the Naval Research Laboratory and the Office of Naval Research.