Plastic waveguides for future communication networks

May 11, 2015 // By Wouter Volkaerts
Researchers from the KU Leuven ESAT-MICAS research group in Belgium build a multi-gigabit communication link using a plastic fiber as transmission channel.

The link consists of 120GHz transmitter and receiver chips with on-chip antenna and a Teflon tube which guides the signal from the transmitter to the receiver. Such a plastic fiber is a cheap and low-weight transmission channel for millimeter wave (mmWave) frequencies (30GHz – 300GHz). Data rates up to 12.7Gbps and distances up to 7 meters have been achieved.

Because of technology advances it is now possible to integrate entire mmWave transceivers in a cheap CMOS technology. The advantage of entering the mmWave range is the large bandwidth which is available. With simple modulation schemes and circuit techniques high data rates can easily be achieved and the low system complexity results in low power consumption.

These high operating frequencies also enables the integration of on-chip antennas resulting in a compact and robust system. On the other hand, the transistor gain reduces for higher frequencies so there is a limit on the operating frequency. Another drawback is that at mmWave frequencies wireless transmission is challenging due to the high free space path loss which is frequency dependent.

As consequence the transmission distance is limited to the cm-range or expensive and bulky directive antennas have to be used. With plastic waveguides the transmission distance of mmWave signals can easily be extended into the meters-range. The large available bandwidths can be used to develop gigabit communication link over larger distances.

Plastic waveguide links are a valuable alternative for copper or optical links when reliable, cheap, multi-gigabit, low energy data transmission over meters distance is required. Copper links suffer from a limited bandwidth and large channel losses which limits the transmission distance.

They also have EMI problems. Optical links on the other hand can easily reach a high data rate over very large distances because their low-loss channel. However, they need electrical-optical converters and are too costly to deploy for short distances. For transmission distances up to tens of meters the plastic waveguide addresses