The basis of the new stopwatch is an advanced optical detector, with graphene at the core. The sensor reacts quickly to incident light across most wavelengths (from infrared radiation to terahertz radiation).
The basis of the detector is described as straightforward and not very remarkable to look at: a tiny flake of graphene located on silicon carbide, together with an antenna. This basis structure hides the science behind the invention.
The science, according to a research note, is based on a new property of graphene. Graphene is a carbon-based material, that is very thin (just one atom thick), very light, and very strong. The material also makes for an effcient semiconductor. With the new development, the research team found that graphene can detect light across a wide range of photon energies and convert these into electric signals.
Based on this, the graphene flake together with the antenna assembly absorbs light and transfers the energy from the absorbed photons to the electrons within the graphene. The electrons raise the level of electrical resistance in the detector which produces pulsating electric signals.
Speaking with Controlled Environments magazine, lead researcher Dr. Stephan Winnerl noted: “In contrast to other semiconductors like silicon or gallium arsenide, graphene can pick up light with a very large range of photon energies and convert it into electric signals. We only needed a broadband antenna and the right substrate to create the ideal conditions.”
The detector is so accurate that it can detect incident light in just 40 picoseconds (with one picosecond being a trillionth of a second.) The stopwatch will be used where a high degree of accuracy is required. For example, with the synchronization of laser systems. With laser systems the pulses of lasers must be exactly synchronized and the graphene based device has sufficient accuracy at which to do this.
The watch was constructed at the institute Helmholtz-Zentrum Dresden-Rossendorf (HZDR)’s Institute of Ion Beam Physics and Materials Research. The experiment has been published in the journal Optics Express, in a paper called “Universal ultrafast detector for short optical pulses based on graphene.”
