the problems of the copper and optical links. There is no EMI, no excessive channel loss and no power consuming electrical-optical conversion.
A large range of plastic fibers can be used to guide mmWaves. Circular or rectangular, hollow or filled, polypropylene, polystyrene, polyethylene or Teflon fibers are suited for this. The dimensions of these fibers are in the millimeter range or below and are related to the frequency of the transmitted signal.
For example, measurements of a hollow, circular Teflon waveguide with outer diameter of 2mm and inner diameter of 1mm show a loss of 2.5dB/m at 120GHz. This excellent result is achieved with a plastic fiber which is designed for other applications than mmWave transmission.
Optimizing the waveguide for data transmission will lead to even better results. In optical communication over 1mm plastic optical fiber the data rate is limited by dispersion. When transmitting mmWaves through these plastic fibers, the wavelength and the dimensions of the fiber are in the same range and the number of transmitted modes is very low. As a result modal dispersion is eliminated.
A demonstrator of the entire link is made. The demonstrator uses integrated antennas which perform the coupling between the transmitter and receiver chips and the plastic waveguide.
The chips directly launch an electromagnetic wave into the plastic waveguide and no electrical-optical conversion is required. No accurate alignment of the connector is needed. This makes this solution more robust against mechanical vibrations and results in cheap connectors.
Ref: W. Volkaerts, N. Van Thienen, and P. Reynaert, “An FSK plastic waveguide communication link in 40nm CMOS,” in Solid- State Circuits Conference - (ISSCC), 2015 IEEE International, Feb 2015, pp. 1–3.
This demonstrator uses continuous-phase FSK modulation to reduce the power consumption and to improve the link energy efficiency to 1.8pJ/bit/m for a 4-meter distance and a data rate of 7.4Gbps. The maximum data rate is 12.7Gbps for a 1-meter link and the maximum