Utilising unused bandwidth and switching polarity more efficiently in Nature Photonics
On Monday 3 October, the scientific journal Nature Photonics published two papers written by physicists at Radboud University and the FELIX Lab. Both offer longer-term solutions for current problems within communication technology.
Researchers Giel Berden and Afric Meijer discovered a method for utilising unused bandwidth from the overfull wireless network, namely the terahertz band. Researchers from the FELIX Laboratory of Radboud University developed an 'Optical Single Side Band (OSSB) modulator'. With this terahertz waves can be transmitted through a glass fibre without disruption.
Unless it is processed, laser light generates two side bands (colours) that interfere with each other. The modulator published about in Nature Photonics is a method that prevents this distortion of information.
"Although our publication is a genuine proof of concept, many additional steps are still needed to apply the technique, such as miniaturising the design for microfabrication and improvements in efficiency. We now hope that industry will further elaborate this technique," says FELIX researcher Giel Berden.
The THz-OSSB modulator is a by-product of TeraOptronics' research on the THz laser FLARE at Radboud University. "The device that is used to determine the colour of the FLARE laser light was also ideally suited to observe THz-OSSB," says Meijer. Co-author Wim van der Zande, currently Director of Research at ASML, adds: "The exceptional terahertz laser FLARE and Afric's interest in expanding communication networks with the terahertz frequency band were both needed to make this impact in a discipline that is new for us."
Switching using an electric field
Magnet experts Alexej Kimel and Rostislav Mikhaylovskiy discovered that it should be possible to rapidly reverse the polarity of magnets using weak electrical pulses. This would make a far more energy-efficient form of data storage possible.
"Our discovery is the realisation of the long-desired technological ambition of being able to rapidly and directly manipulate magnetic bits using an electric field. For this we use terahertz frequencies," says Rostislav Mikhaylovskiy, who led the project at Radboud University. The work builds upon the research of Theo Rasing's group that uses light to reverse the polarity of magnets. The new method is just as fast, but uses far less energy. That is currently an important theme in data technology.
Mikhaylovskiy expects that the discovery can be applied in data storage in the foreseeable future by using high-frequency transistor-amplifiers and the right antennae. Follow-up research will take place at FELIX, the free-electron laser facility of Radboud University. The lasers there are highly suitable for testing the terahertz control of magnetisation. The wavelength of the FELIX laser is the same as that used in this study. Furthermore, the wavelength of the FELIX laser can be adjusted to search for the fastest and most energy-efficient way of switching magnetic bits.
Referencies
A.S. Meijer, G. Berden, D.D. Arslanov, M. Ozerov, R.T. Jongma & W.J. van der Zande, 'An ultrawide-bandwidth single-sideband modulator for terahertz', Nature Photonics, 3 October 2016, doi: 10.1038/nphoton.2016.182
S. Baierl, M. Hohenleutner, T. Kampfrath, A.K. Zvezdin, A.V. Kimel, R. Huber & R.V. Mikhaylovskiy, 'Nonlinear spin control by terahertz-driven', Nature Photonics, 3 October 2016, doi: 10.1038/nphoton.2016.181