Squeezing Light Out of Silicon

IEEE Spectrum  April 8, 2020 Cubic Si, Ge and SiGe alloys are all indirect-bandgap semiconductors that cannot emit light efficiently. An international team of researchers (the Netherlands, Germany, Austria) has demonstrated efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. They have shown that by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously tuned over a broad range, while preserving the direct bandgap. Their experimental findings are in excellent quantitative agreement with ab initio theory. Hexagonal SiGe embodies an ideal material system in which to combine electronic and optoelectronic functionalities on a single […]

Researchers turn off backscattering, aim to improve optical data transmission

Nanowerk  August 12, 2019 The most common manifestation of subwavelength disorder is Rayleigh light scattering, which is observed in nearly all waveguiding technologies today and can lead to both irreversible radiative losses as well as undesirable intermodal coupling. A team of researchers in the US (University of Illinois, University of Maryland, NIST) has demonstrated an optomechanical approach for dynamically suppressing Rayleigh backscattering within dielectric resonators by locally breaking the time-reversal symmetry in a silica resonator through a Brillouin scattering interaction that is available in all materials. They confirmed complete suppression of Rayleigh backscattering in their experiment through two independent measurements—the […]

Physicists’ finding could revolutionize information transmission

Phys.org  July 9, 2019 An international team of researchers (USA – UC Riverside, National High Magnetic Field Laboratory, State University of Florida, Japan) has observed, characterized, and controlled dark trions in tungsten diselenide. Because a trion contains three interacting particles, controllable spin and momentum indices and a rich internal structure, it can carry much more information than a single electron. The lifetime of dark trions is more than 100 times longer than the more common bright trions. The long lifetime enables information transmission by trions over a much longer distance. They demonstrated continuous tuning from positive dark trions to negative […]