Phys.org April 15, 2024 The stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge. An international team of researchers (Germany, Spain, USA – SLAC National Accelerator Laboratory, Stanford University) demonstrated a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform resulted in optical control of time-reversal symmetry breaking and the realization of the topological Haldane model in a laser-dressed two-dimensional insulating crystal. […]
Tag Archives: Light
Light and sound waves reveal negative pressure
Phys.org September 25, 2023 Pressure is encountered in various fields – atmospheric pressure in meteorology, blood pressure in medicine, etc. Examining the physical properties of materials under a wide range of thermodynamic states is a challenging problem due to the extreme conditions the material must experience. Such temperature and pressure regimes, which result in a change in the refractive index and sound velocity, can be accessed by optoacoustic interactions such as Brillouin–Mandelstam scattering. An international team of researchers (Germany, France, Australia) demonstrated the Brillouin–Mandelstam measurements of nanolitre volumes of liquids in extreme thermodynamic regimes enabled by a fully sealed liquid-core […]
Copper-doped tungstic acid nanocrystals transform infrared light conversion
Nanowerk September 13, 2023 The technology to utilize the full spectrum of solar radiation is still in its infancy as conventional methods constrain their all-solar response. Researchers in Japan have proposed using – submerged photosynthesis of crystallites (SPsC). They showed that strategic doping with copper and oxygen vacancies can induce opto-critical phases from the non-stoichiometric tungstic acids. These opto-critical phases enabled a dynamic equilibrium shift in lattice defect stabilization, facilitating an unprecedented whole solar wavelength response. The response manifested photo-assisted water evaporation, and photo-electrochemical characteristics. According to the researchers their strategy of harnessing all-solar energy, the one-pot SPsC strategy, may […]
Scientists trap light inside a magnet
Science Daily August 16, 2023 Recent studies were able to modify some of the most defining features of light utilizing the strong coupling of light and matter in optical cavities. An international team of researchers (City College of New York, City University of New York, University of Washington, University of Michigan, MIT, Spain) studied the magneto-optical properties of a van der Waals magnet that supports strong coupling of photons and excitons even in the absence of external cavity mirrors. In the layered magnetic semiconductor CrSBr polaritons were shown to substantially increase the spectral bandwidth of correlations between the magnetic, electronic, […]
Scientists invent smallest known way to guide light
Science Daily August 11, 2023 Addressing the optical mismatch between components typically results in compromises in size and performance of chip-scale optical circuits for practical devices. Researchers at the University of Chicago showed that they could confine and guide light in an ultrathin two-dimensional (2D) material (<1 nanometer thick). They made three-atom-thick waveguides—δ waveguides—based on wafer-scale molybdenum disulfide (MoS2) monolayers that could guide visible and near-infrared light over millimeter-scale distances with low loss and an efficient in-coupling. The extreme thinness provided a light-trapping mechanism analogous to a δ-potential well in quantum mechanics and enabled the guided waves that were essentially […]
New technique measures structured light in a single shot
Phys.org August 8, 2023 Orbital angular momentum (OAM) spectrum diagnosis is a fundamental building block for diverse OAM-based systems. Among others, the simple on-axis interferometric measurement can retrieve the amplitude and phase information of complex OAM spectra in a few shots. Yet, its single-shot retrieval remains elusive, due to the signal–signal beat interference inherent in the measurement. Researchers in Switzerland have introduced the concept of Kramers–Kronig (KK) receiver in coherent communications to the OAM domain, enabling rigorous, single-shot OAM spectrum measurement. They explained in detail the working principle and the requirement of the KK method and applied the technique to […]
Topologically structured light detects the position of nano-objects with atomic resolution
Phys.org May 19, 2023 Despite recent progress in optical imaging and metrology there remains a substantial resolution gap between atomic-scale transmission electron microscopy and optical techniques. An international team of researchers (UK, Singapore) demonstrated atomic scale metrology by collecting single-shot images of the diffraction pattern of topologically structured light scattered on a suspended nanowire to determine its position relative to the fixed edges of the sample. They trained a deep learning algorithm that could predict the positions of a given nanowire based on the scattered light pattern recorded by the team’s sensor. If a sub-wavelength object moves in such a […]
Scientists push the boundaries of manipulating light at the submicroscopic level
Phys.org March 2, 2023 How tightly the light is confined determines the limits for the observability of nanoparticles, as well as the intensity and the precision of light-based devices. An international team of researchers (UK, Germany) has developed a general theory describing multi-mode light–matter coupling in systems of reduced dimensionality. The researchers explored their phenomenology, validating their theory’s predictions against numerical electromagnetic simulations. They characterized the spectral features linked with the multi-mode nature of the polaritons and showed how the interference between different photonic resonances can modify the real-space shape of the electromagnetic field associated with each polariton mode. According […]
Researchers devise a new path toward ‘quantum light’
Science Daily February 2, 2023 Strongly driven systems of emitters offer an attractive source of light over broad spectral ranges up to the X-ray region. A key limitation of these systems is that the light they emit is mostly classical. An international team of researchers (USA – Harvard University, MIT, UK, Israel, Austria) overcame this constraint by building a quantum-optical theory of strongly driven many-body systems, showing that the presence of correlations among the emitters creates emission of non-classical many-photon states of light. They considered the example of high-harmonic generation, by which a strongly driven system emits photons at integer […]
New device can control light at unprecedented speeds
Nanowerk November 29, 2022 Harnessing the full complexity of optical fields requires the complete control of all degrees of freedom within a region of space and time. An international team of researchers (USA – MIT, industry, State University of New York, Rochester Institute of Technology, ARL (Rome), UK, Canada) resolved this challenge with a programmable photonic crystal cavity array enabled by four key advances: (1) near-unity vertical coupling to high-finesse microcavities through inverse design; (2) scalable fabrication by optimized 300 mm full-wafer processing; (3) picometre-precision resonance alignment using automated, closed-loop ‘holographic trimming’; and (4) out-of-plane cavity control via a high-speed μLED […]