MIT Researchers Create New Cable Outperforming Copper

Recently, researchers from MIT have developed a new polymer cable that is as thin as hair but can transmit over 100Gbps. What challenges do copper and fibre optic cables face, what did the researchers develop, and how will it help with the future of technology?

What challenges do current cables face?

Choosing the right cable for a job can be challenging as many factors can affect the performance of a cable. For example, the environment may experience mechanical strain, and as such the cable may require armoured protection. Another example would be electrical noise present in the environment, and this may require the use of twisted pairs to help mitigate against common-mode noise.

While copper cables have been the de facto cable for carrying data, they are quickly being replaced with fibre optic cables. However, it should be noted that fibre optic cables are replacing copper cables because they offer a greater bandwidth (i.e. more bits per second), but this greater bandwidth is nothing to do with the speed at which light travels (in fact, light is slower in a fibre optic cable than an electrical pulse in a copper wire). 

The ability to send multiple frequencies of light into a cable as well as being able to rapidly modulate light is what makes fibre optic cables ideal for large amounts of data transmission. But, just like copper cables, fibre optic cables also have their disadvantages, and one disadvantage, in particular, is so bad that it prevents their use in everyday electronics.

Simply put, fibre optic cables are light guides and as such cannot directly interface with any electrical system (unlike copper cables). This means that conversion stages are required between the cable and any connected electrical system. Such conversion steps are bulky, expensive, and potentially impeding the ability to transfer data. Therefore, fibre optic cables are generally limited to high-speed internet connections between ISPs and homes.

MIT Researchers Develop New Polymer Cable

Recently, researchers from MIT have developed a new cable made from a polymer material that has been demonstrated to offer far higher data rates than those of copper while combining the best features of copper and fibre optic cables. According to the researchers, speeds of up to 100Gbps have been achieved between two circuits using a 30cm length of the new cable which has a cross-section of 0.4mm x 0.25mm. 

The research, which has been partly funded by Intel, demonstrates a cable that is superior to copper, but cheaper to the manufacturer. The research team hopes that the new cables will see early adoption in server farms that generally have high data rate requirements. The use of a plastic polymer has not only resulted in a cable that is lighter but the flow of electrons can be detected from the outside without interfering with the cable, something that cannot be done with copper.

However, very little detail surrounds the actual construction of the cable as well as how data is transmitted. The researchers mention that the cable has both properties of copper and fibre optic, but then proceed to give mixed messages on how data is transmitted. Some reports suggest that it is an electrical current that is being detected (i.e. the ability to detect electron flow), but then go on to mention that multiple frequencies of electromagnetic waves (i.e. photons) can be transmitted simultaneously. 

This confusion continues when the researchers talk about interfacing the cable with two semiconductor devices. Since fibre optic cables use photons to transfer data, they cannot directly interface with an electrical circuit and therefore require a conversion stage (such as a photodiode and laser). However, the researchers mention that the cable can directly interface with electrical devices suggesting that the cable conducts electrical signals.

How can the new cable help electronics?

Despite the confusing statements regarding the exact nature of the cable, if the researchers are correct in their findings, then the data communications world could very well be transformed. The ability to send data faster not only helps with improving internet-based services (which will continue to be an important issue as people work from home), but also helps to improve computer hardware. 

While it is unlikely that these cables will be used in smartphones, they could very well be used in USB and PCIe applications where speed is everything. Internal buses in PCs such as those between I/O and the motherboard are one of the main throttles in the performance of a computer when transferring data from external devices. But the use of high-speed cables can also enable streaming video data to external devices at high resolutions or even enable a high-speed communication lane for external co-processors such as AI accelerators.