Physics World June 29, 2018 An international team of researchers (Israel, USA – University of Central Florida, University of Michigan, China, Japan) used a cylindrical, silica-glass resonator that is rotating on a turbine. An optical fibre is located 320 nm above the spinning resonator. Light travelling along the fibre interacting with the nearby resonator via the light’s short-range evanescent field perceives it to be less dense than light travelling in the opposite direction. This difference in apparent density results in different indices of refraction for light moving in opposite directions allowing the researchers to pass light of the same frequency […]
Category Archives: Photonics
Cooling by laser beam
Science Daily June 8, 2018 Researchers in Italy explain that the laser pulse can, in some circumstances, populate high-energy states, which heat up, and simultaneously depopulate low energy ones, which thus cool down which is responsible for superconductivity. This selective cooling, shown rigorously in a very simplified theoretical model, could explain not only the experimental observations, but also open the way to new and potentially important research activities… read more. TECHNICAL ARTICLE
Light-bending nano-patterns for LEDs
Nanowerk June 8, 2018 Researchers in Singapore designed and experimentally realized high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. They demonstrated a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies, and the broad functionality that can be realized on this platform. The broadband response in the blue wavelength range of 430–470 nm. The nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ […]
New laser makes silicon ‘sing’
Eurekalert June 7, 2018 To amplify silicon laser with sound, a team of researchers in the US (Yale University, Northern Arizona University, UT Austin) used a nanoscale waveguide that is designed to tightly confine both light and sound waves and maximize their interaction. The waveguide has two distinct channels for light to propagate which allows shaping of the light-sound coupling in a way that permits remarkably robust and flexible laser designs. While the system is clearly an optical laser, it also generates very coherent hypersonic waves. According to the researchers these properties may lead to several potential applications ranging from […]
Photonics – Getting into the groove
Nanowerk June 8, 2018 An international team of researchers (Singapore, UK, Saudi Arabia, Germany) fabricated, analyzed and modeled a system consisting of the nano-grooved gold film topped with an atomically thin flake of tungsten selenide. The result was a remarkable 7,000-fold multiplication of second harmonic generation (SHG) by which two photons combine to produce a single photon with double the energy. They were able to combine the advantages of both materials to achieve a flexible, ultra-compact, and efficient device for SHG, with potential applications for optical frequency doubling in nanoscale devices… read more. TECHNICAL ARTICLE
Researchers achieve almost instant magnetization of matter by light
Phys.org May 28, 2018 The magnetization of a material is associated with the spatial ordering of the spins of its constituent particles. An international team of researchers (Brazil, Austria) demonstrated that light resonant with the band gap forces the antiferromagnetic semiconductor EuSe to enter ferromagnetic alignment in the picosecond timescale. By increasing the light intensity, the whole of the illuminated region can be fully magnetized… read more. TECHNICAL ARTICLE
Detecting the shape of laser pulses
Science Daily May 17, 2018 The existing method to study the shape of laser pulses relies on the generation of attosecond X-ray pulses which requires detection equipment in vacuum chambers. Researchers in South Korea demonstrate that an arbitrary time-dependent laser field can be directly sampled using subcycle tunneling ionization in a gaseous medium or in air. This unique approach enables the complete temporal characterization of the laser field, including its carrier-envelope phase, for a broad spectral range in ambient air, providing a universal tool for the precise measurement of the laser field… read more. Open Access TECHNICAL ARTICLE
A microscopic roundabout for light—team develops a magnet-free optical circulator
Phys.org May 4, 2018 To break the symmetry of light propagation, instead of magnet, an international team of researchers (The Netherlands, USA – UT Austin, City University of New York, City College of New York) created circulating behavior using a microscale glass ring resonator by letting light in the ring interact with the ring’s mechanical vibrations. Careful control of the optical paths in the structure ensures that light from each input constructively interferes in exactly the right output. They demonstrated that circulation can be actively tuned and it can be turned on and off by controlling the frequency and power […]
Picking one photon out of the flow
Science Daily May 3, 2018 An international team of researchers (Denmark, Germany, USA – NIST) has implemented photonic memory. The general idea was to first store an optical field, and then send another one through the medium. Photons in the second beam take notice of the stored photons and interact with them in such a way that exactly one photon is tagged and later discarded on retrieval. Being robbed of a single photon, the original light beam is left in a peculiar quantum state that has numerous scientific and technological applications. This method paves the way towards future quantum communication […]
A powerful laser breakthrough
Science Daily April 27, 2018 A team of researchers in the US (Lehigh University, Sandia National Laboratory) demonstrated a new hybrid grating scheme that uses a superposition of second and fourth-order Bragg gratings that excite a symmetric mode with much greater radiative efficiency. The scheme is implemented for terahertz QCLs with metallic waveguides. Peak power output was 170 mW. The hybrid grating scheme is simpler to implement than distributed feedback (DFB) schemes and could be used to increase power output for surface-emitting DFB lasers at any wavelength… read more. Open Access TECHNICAL ARTICLE