Due to their high frequency, light waves are ideally suited for fast data transmission. Sent through optical fibers, they can easily transport hundreds of billions of bits (gigabits) per second. The "last mile" from a central fiber optic cable to a home Internet connection is the most complex and costly. Alternatives such as 4/5G mobile telephony are cheaper, but cannot offer all users the high transfer rates required by data-intensive applications such as streaming TV at the same time.
Jürg Leuthold, Professor at the Institute for Electromagnetic Fields at ETH Zurich, and his colleagues, with the support of colleagues from the University of Washington in Seattle, now developed a new type of light modulator with which the last mile can be covered cost-effectively and energy-efficiently with extremely high-frequency millimeter waves.
In order to convert data encoded on millimeter waves into light pulses for transmission in a glass fiber, one normally needs very fast - and therefore expensive - electronic components. The millimeter waves must first be received by an antenna, then amplified and finally fed into a light modulator, which translates the data contained in the millimeter waves back into light pulses.
Leuthold and his colleagues succeeded in building a light modulator that does not require any electronics or batteries. This makes the modulator completely independent of an external power supply and also extremely small, so that in principle it can be attached to any lamppost. From there, it can then receive data from individual houses via millimeter wave signals and feed it directly into the central fiber optic, according to the Swiss researchers.
The ETH researchers' modulator consists of a chip less than one millimetre in size that also contains the millimetre wave antenna. This antenna receives the millimetre waves and converts them into an electrical voltage. The voltage then drops in the middle of the chip over a thin gap, the actual heart of the modulator.