Phys.org September 28, 2021 After theoretical and computer modeling studies an international team of researchers (France, USA – Lawrence Livermore National Laboratory) proposed a scheme to explore regimes of strong-field quantum electrodynamics (SF QED) otherwise unattainable with the currently available laser technology. The scheme relies on relativistic plasma mirrors curved by radiation pressure to boost the intensity of petawatt-class laser pulses by Doppler effect and focus them to extreme field intensities. They showed that very clear SF QED signatures could be observed by placing a secondary target where the boosted beam is focused. This may finally crack the elusive physics […]
Tag Archives: Lasers
Tiny lasers acting together as one: Topological vertical cavity laser arrays
Phys.org September 24, 2021 Vertical-Cavity Surface-Emitting Lasers (VCSEL) device has miniscule size of only a few microns, which sets a stringent limit on the output power it can generate. An international team of researchers (Israel, Germany) utilized the concepts of topological photonics with VCSELs that emit light vertically, while the topological process responsible for the mutual coherence and locking of the VCSELs occurs in the plane of the chip. It resulted in a powerful but very compact and efficient laser, not limited by a number of VCSEL emitters, and undisturbed by defects or altering temperatures. The topological principle of this […]
Electrons in quantum liquid gain energy from laser pulses
Phys.org July 13, 2021 Laser-assisted electron scattering (LAES), a light–matter interaction process that facilitates energy transfer between strong light fields and free electrons, has so far been observed only in gas phase. An international team of researchers (Austria, Japan) has detected LAES at condensed phase particle densities, for which they created nano-structured systems consisting of a single atom or molecule surrounded by a superfluid He shell of variable thickness. They observed that free electrons, generated by femtosecond strong-field ionization of the core particle, can gain several tens of photon energies due to multiple LAES processes within the liquid He shell. […]
Lighting it up: Fast material manipulation through a laser
Phys.org April 21, 2021 An abrupt change in the Fermi surface topology, also called Lifshitz transition, can lead to the emergence of fascinating phenomena like colossal magnetoresistance and superconductivity. Controlling the electrons’ arrangement has been a key topic for decades. An international team of researchers (Germany, Sweden, US – research organization) has massively cut down the switching time to only 100 femtoseconds by shooting ultrashort optical laser pulses at a semi-metallic crystal composed of tungsten and tellurium atoms. Shining light on the crystal encourages it to reorganize its internal electronic structure, which also changes the conductivity of the crystal. They […]
Scientists propose novel self-modulation scheme in seeded free-electron lasers
Phys.org March 11, 2021 Seeded free-electron lasers (FELs), which use the frequency up-conversion of an external seed laser to improve temporal coherence, are ideal for providing fully coherent soft x-ray pulses. However, it is difficult to operate seeded FELs at a high repetition rate due to the limitations of present state-of-the-art laser systems. Researchers in China have developed self-modulation method for enhancing laser-induced energy modulation, thereby significantly reducing the requirement of an external laser system. They have experimentally realized high harmonic generation in a seeded FEL using an unprecedentedly small external laser-induced energy modulation. The results pave a way for […]
Colloidal quantum dot lasers poised to come of age
Nanowerk February 18, 2021 A team of researchers in the US (Los Alamos National Laboratory, Argonne National Laboratory) sums up the recent progress in colloidal-quantum-dot research and highlights the remaining challenges and opportunities in the rapidly developing field, which is poised to enable a wide array of new laser-based and LED-based technology applications. According to the researchers these tiny specs of semiconductor matter can generate spectrally tunable lasing light, opening tremendous opportunities in areas of photonic circuits, optical communications, lab-on-a-chip sensing, and medical diagnostics. They conclude that the accumulated knowledge, along with the approaches developed for manipulating the optical-gain properties […]
First bufferless lasers grown directly on silicon wafers in Si-photonics
Nanowerk March 4, 2020 In conventional approaches of integrating III-V lasers on Si thick III-V buffers up to a few micrometers are used to reduce the defect densities, which posses huge challenges for efficient light interfacing between the epitaxial III-V lasers and the Si-based waveguides. Based on numerical simulations an international team of researchers (China, Hong Kong) designed and fabricated a novel growth scheme to eliminate the requirement of thick III-V buffers and thus promoted efficient light coupling into the Si-waveguides. They demonstrated the 1.5 µm III-V lasers directly grown on the industry-standard 220 nm SOI wafers using metal organic […]
A laser for penetrating waves
Phys.org August 19, 2019 An international team of researchers (France, Poland, Germany, Russia, Czech Republic) used a heavy metal alloy of mercury, cadmium and tellurium (HgCdTe) that is used for highly sensitive thermal imaging cameras. Mercury, cadmium and tellurium contents can be very precisely chosen, which makes it possible to fine-tune the band gap. The material showed properties similar to graphene, but without the issue of strong Auger scattering. When electric current is applied it gets rid of its energy in the form of terahertz radiation. By varying an additional magnetic field of only about 200 millitesla, the experts were able […]
Researchers discover anti-laser masquerading as perfect absorber
Phys.org February 15, 2019 Researchers at Duke University constructed zirconia ceramic surface dimpled with cylinders like the face of a Lego brick. After computationally modeling the device’s properties by altering the cylinders’ size and spacing, the researchers realized that they had actually created a more fundamental kind of coherent perfect absorber (CPA) which can absorb both aligned and misaligned waves. Unlike typical CPAs the new material has three variables the cylinders’ radius, height and periodicity. This gives a lot of flexibility for tailoring the CPA model and put them in the frequency spectrum where needed…read more. TECHNICAL ARTICLE
Laser capable of emitting light quiet enough to move demanding scientific applications
Science Daily February 1, 2019 Under a DARPA sponsored initiative an international team of researcher (USA – UC Santa Barbara, industry partners, Northern Arizona University, Yale University, Portugal) has developed a chip-scale laser capable of emitting light with a fundamental linewidth of less than 1 Hz. They leveraged stimulated Brillouin scattering to build the lasers. The circuits were built with waveguides that are extremely low loss. They formed into a Brillouin laser ring cavity on the chip. They can store an extremely large number of photons on the chip, handle extremely high levels of optical power inside the optical cavity […]