Phys.org July 5, 2024 Coherent light-matter interactions mediated by opto-magnetic phenomena like the inverse Faraday effect (IFE) are expected to provide a non-thermal pathway for ultrafast manipulation of magnetism on timescales as short as the excitation pulse itself. As the IFE scales with the spin-orbit coupling strength of the involved electronic states, photo-exciting the strongly spin-orbit coupled core-level electrons in magnetic materials appears as an appealing method to transiently generate large opto-magnetic moments. An international team of researchers (Germany, France, Canada, Italy, Spain, Slovenia, Sweden, UK) investigated this scenario in a ferrimagnetic GdFeCo alloy by using intense and circularly polarized […]
Category Archives: Light
Researchers demonstrate new way to ‘squeeze’ infrared light
Science Daily June 10, 2024 Recent theoretical studies have suggested that transition metal perovskite oxide membranes can enable surface phonon polaritons in the infrared range with low loss and much stronger subwavelength confinement than bulk crystals. Such modes, however, have not been experimentally observed so far. An international team of researchers (USA – North Carolina State University, Lawrence Berkeley National Laboratory, Stanford University, SLAC National Accelerator Laboratory, Switzerland) studied the phonon polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3 transferred on metallic and dielectric substrates. They observed a symmetric-antisymmetric mode splitting which gave rise to epsilon-near-zero and Berreman […]
Internet can achieve quantum speed with light saved as sound
Phys.org April 15, 2024 An international team of researchers (Denmark, Croatia) demonstrated a memory for light based on optomechanically induced transparency. They achieved a long storage time by leveraging the ultralow dissipation of a soft-clamped mechanical membrane resonator, which oscillated at MHz frequencies. At room temperature, they demonstrated a lifetime T1≈23 ms and a retrieval efficiency η≈40% for classical coherent pulses. According to the researchers the storage of quantum light is possible at moderate cryogenic conditions (T≈10K) and such systems could find applications in emerging quantum networks, where they could serve as long-lived optical quantum memories by storing optical information in […]
Could new technique for ‘curving’ light be the secret to improved wireless communication?
Science Daily April 9, 2024 A key challenge in millimeter-wave and terahertz wireless networks is blockage of the line-of-sight path between a base station and a user. A team of engineers in the US (University of Missouri-Kansas City, Rice University, Brown University) proposed a solution to this problem leveraging the fact that, in such scenarios, users are likely to be located within the electromagnetic near field of the base station, which opens the possibility to engineer wave fronts for link maintenance. They showed that curved beams, carrying data at high bit rates, could realize a link by curving around an […]
Propagating dimensions of light: Deforming versatile non-diffractive beams along the optical trajectory
Phys.org April 8, 2024 Despite the numerous types of non-diffraction beam generation technologies, the 3D deformation and intricate wavefront shaping of structures during propagation have yet to be studied through the lens of nanophotonic devices. An international team of researchers (Singapore, Spain) demonstrated the dynamic conversion of a circular Airy beam (CAB) to a Bessel beam with a single-layer spin-selective metasurface. The spatial transformation developed from the interplay of 1D local and 2D global phases, facilitating the 3D control of non-diffractive light fields. Overall phase gradient and orbital angular momentum altered the propagation direction and transverse fields of complex amplitude […]
Breakthrough in light manipulation: Unveiling novel finite barrier bound states
Phys.org March 22, 2024 A boundary mode localized on one side of a finite-size lattice can tunnel to the opposite side which results in unwanted couplings and the tunneling probability decays exponentially with the size of the system which requires many lattice sites before eventually becoming negligibly small. An international team of researchers (USA – PNNL, China) showed that the tunneling probability for some boundary modes can apparently vanish at specific wavevectors and a boundary mode can be completely trapped within very few lattice sites where the bulk bandgap is not even well-defined. The number of trapped states equaled the […]
Moebius rings enable new ways to control light in twisted spaces
Nanowerk March 21, 2024 Modulation of topological phase transition has been realized in Euclidean systems. However, the spin-controlled topological phase transition in non-Euclidean space has not yet been explored. Researchers in China proposed a non-Euclidean configuration based on Möbius rings, and demonstrated the spin-controlled transition between the topological edge state and the bulk state. They utilized 8π period Möbius rings to construct both one-dimensional and two-dimensional coupled resonator optical waveguide (CROW) configurations which supported topological edge states excited by circularly polarized light of a specific handedness, while forbidding the excitation of topological modes by light of the opposite handedness. This […]
Novel method for controlling light polarization uses liquid crystals to create holograms
Phys.org March 11, 2024 Metasurfaces are candidates for vectorial optics polarization, but their static post-fabrication geometry largely limits dynamic tunability. Liquid crystal (LC) is usually employed as an additional index-changing layer together with metasurfaces. However, most of the reported LCs only impart a varying but uniform phase on top of that from the metasurface. An international team of researchers (China, Singapore) pixelated a single-layer LC to display versatile and tunable vectorial holography, in which the polarization and amplitude could be arbitrarily and independently controlled at varying spatial positions. The subtle and vectorial LC-holography highlighted the broadband and electrically switchable functionalities. […]
Light stimulates a new twist for synthetic chemistry
Nanowerk February 28, 2024 Photoinduced concerted multiple-bond rotation has been proposed in some biological systems. However, the observation of such phenomena in synthetic systems has been a challenge in the photochemistry field. Researchers in Japan described a chalcogen-substituted benzamide system that exhibits photoinduced dual bond rotation in heteroatom-containing bonds. Introduction of the chalcogen substituent into a sterically hindered benzamide system provided sufficient kinetic stability and photosensitivity to enable the photoinduced concerted rotation. The presence of two different substituents on the phenyl ring in the thioamide derivative enabled the generation of a pair of enantiomers and E/Z isomers. Using these four […]
Measuring the properties of light: Scientists realize new method for determining quantum states
Nanowerk February 25, 2024 Superconducting nanowire single-photon detectors (SNSPDs) have been widely used to study the discrete nature of quantum states of light in the form of photon-counting experiments. Researchers in Germany showed that SNSPDs can also be used to study continuous variables of optical quantum states by performing homodyne detection at a bandwidth of 400 kHz. By measuring the interference of a continuous-wave field of a local oscillator with the field of the vacuum state using two SNSPDs, they showed that the variance of the difference in count rates was linearly proportional to the photon flux of the local […]