In May 2017 we reported on a new project at the Institute of Low Temperature and Structure Research (Wroclaw, Poland) that developed a new efficient white light source that uses graphene foam excitated by a continuous-wave laser.
The project is still in progress, and the researchers demonstrated the technology at IDTechEx Graphene & 2D Materials Europe 2019 earlier this month, as can be seen in our video above.
Researchers from the Moscow Institute of Physics and Technology (MIPT) in Russia and Tohoku University in Japan have explained the phenomenon of particle-antiparticle annihilation in graphene, recognized by specialists as Auger recombination.
Two scenarios of electron-hole recombination in graphene: radiative recombination (left) and Auger recombination (right) in which the energy is picked up by an electron passing by
Despite persistently being spotted in experiments, it was thought to be prohibited by the fundamental physical laws of energy and momentum conservation. The theoretical explanation of this process has until recently remained one of the greatest puzzles of solid-state physics.
Researchers at the Institute for Basic Science (IBS, South Korea), in collaboration with teams from the University of Birmingham and the Korea Advanced Institute of Science and Technology (KAIST), have developed unique graphene-based lenses with tunable features. These optical devices, made of graphene and a punctured gold surface, could become optical components for advanced applications like amplitude tunable lenses, lasers (i.e. vortex phase plates), and dynamic holography.
The scientists explain that metasurfaces are new 2D materials that can effectively control the electric and magnetic components of light (and other electromagnetic waves) and bend them to chosen directions. Controlling the beam's direction can bring out interesting phenomena; the most incredible being the "invisibility cloak effect", where light waves bypass an object recreating the image beyond the object.
Researchers from CNR-Istituto Nanoscienze, Italy and the University of Cambridge, UK, associated with the Graphene Flagship, have shown that it is possible to create a terahertz saturable absorber using graphene, produced by liquid phase exfoliation and deposited by transfer coating and ink jet printing. The paper reports a terahertz saturable absorber with an order of magnitude higher absorption modulation than other devices produced to date.
A terahertz saturable absorber decreases its absorption of light in the terahertz range (far infrared) with increasing light intensity and has great potential for the development of terahertz lasers, with applications in spectroscopy and imaging. These high-modulation, mode-locked lasers open up many prospects in applications where short time scale excitation of specific transitions are important, such as time-resolved spectroscopy of gasses and molecules, quantum information or ultra-high speed communication.
The EU-funded GOSFEL project (Graphene on Silicon Free Electron Laser), demonstrated a new type of compact laser source, which exploits graphene to create a solid-state free electron laser. Compact and low-cost lasers could benefit many indusries, like communications, security, sensors and more.
Free Electron Lasers (FELs) offer an alternative to conventional lasers being potentially the most efficient, high powered and flexible generators of tunable coherent radiation from the ultra-violet to the infrared. However, currently FELs are prohibitively large and expensive. The GOSFEL project used graphene to create a compact, relatively inexpensive, solid-state version of such a laser.
