Science Daily June 1, 2022 Anderson localization predicts that transport in one-dimensional uncorrelated disordered systems comes to a complete halt, experiencing no transport whatsoever. However, a disordered physical system is always correlated because it must have a finite spectrum. Localization is dominant only for wave packets whose spectral extent resides within the region of the wave number span of the disorder. An international team of researchers (Israel, Germany, Spain) has experimentally shown that Anderson localization can occur and even be dominant for wave packets residing entirely outside the spectral extent of the disorder. The team studied the evolution of wave […]
Tag Archives: Light
A nanoscale 3D structure to control light
Phys.org February 2, 2022 Metamaterials can be engineered to produce desired interactions with light or sound waves. However, functionality of the devices can be limited by the corresponding design space. A team of researchers in the US (Pennsylvania State University, Sandia National Laboratory) leveraged a combination of a genetic algorithm (GA) based optimization method and a membrane projection lithography (MPL) fabrication approach, to demonstrate a quasi-3D metamaterial for broadband asymmetric transmission (AT) of linearly polarized mid-infrared light. An efficient exploration of 3D plasmonic meta-atoms with broken mirror symmetry in the light propagation direction allows the satisfaction of the rigorous conditions […]
Physicists manipulate magnetism with light
Nanowerk January 28, 2022 The non-equilibrium driving of dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. An international team of researchers (USA – MIT, South Korea) achieved this in the van der Waals correlated insulator NiPS3 by photoexciting its newly discovered spin–orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, they observed the coexistence of itinerant carriers produced by exciton dissociation and a long-wavelength antiferromagnetic magnon that coherently processes in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, […]
The perfect trap: a new way to control the polarization of light
Phys.org January 19, 2022 An international team of researchers (Germany, UK, Scotland, Switzerland) has demonstrated that the Kerr effect in a high-finesse Fabry-Pérot resonator can be utilized to control the polarization of a continuous wave laser. They showed that a linearly polarized input field is converted into a left- or right-circularly-polarized field, controlled via the optical power. The observations are explained by Kerr-nonlinearity induced symmetry breaking, which splits the resonance frequencies of degenerate modes with opposite polarization handedness in an otherwise symmetric resonator. According to the researchers in the future one could arrange many of these devices onto a photonic […]
A quantum view of ‘combs’ of light
Phys.org December 16, 2021 An international team of researchers (USA – Stanford University, Germany) used second-order photon correlations to study the underlying quantum processes of soliton microcombs in an integrated silicon carbide microresonator. They showed that a stable temporal lattice of solitons can isolate a multimode below-threshold Gaussian state from any admixture of coherent light and predict that all-to-all entanglement can be realized for the state. Their work opens a pathway toward a soliton-based multimode quantum resource. Microcombs have the potential to enhance countless technologies, including GPS systems, telecommunications, autonomous vehicles, greenhouse gas tracking, spacecraft autonomy and ultra-precise timekeeping…read more. […]
Getting quantum dots to stop blinking
Science Daily November 22, 2021 Quantum dots tendency to blink off at random intervals has hampered its use for biochemical applications. Researchers at MIT have come up with a way to control this unwanted blinking by firing a beam of mid-infrared laser light for an infinitesimal moment which eliminates the quantum dot’s blinking for a relatively long period. According to the researchers the cause of the blinking phenomenon probably has to do with extra electrical charges, such as extra electrons, attaching to the outer part of the quantum dots, altering the surface properties providing alternative pathways for the extra energy […]
Controlling light with a material three atoms thick
Phys.org October 22, 2021 An international team of researchers (USA – Caltech, Japan) constructed a material from black phosphorous which has anisotropic optical properties. As the black phosphorous is a semiconductor, structures built from black phosphorous can control the polarization of light as an electric signal is applied to them. This makes it possible to make an array of these elements each of which can convert the polarization into a different reflected polarization state. A telecommunications device based on thin layers of black phosphorous could tune the polarization of each signal so that they don’t interfere with each other. This […]
Tuning transparency and opacity
Phys.org October 18, 2021 Recently, a new type of wavefront shaping was introduced where the extinction is manipulated instead of the scattered intensity. The underlying idea is that upon changing the phases or the amplitudes of incident beams, the total extinction will change due to interference described by the cross terms between different incident beams. Researchers in the Netherlands have experimentally demonstrated the mutual extinction and transparency effects in scattering media a human hair and a silicon bar. They sent two light beams with a variable mutual angle on the sample. Depending on the relative phase of the incident beams, they […]
Optically generated quantum fluids of light reveal exotic matter-wave states in condensed matter physics
Phys.org September 30, 2021 An international team of researchers (Russia, UK) used all-optical methods to create an artificial lattice whose nodes house polaritons called Lieb lattice, which usually does not occur in nature. Programmable spatial light modulator was used to shape a laser beam into a lattice inside the cavity. The generated polaritons both increased in number and became more energetic where the laser field was most intense and forming condensates at high enough laser power. The high-energy polariton waves escaped the condensates scattered and diffracted across the lattice. When the lattice constant was decreased, the condensates underwent a phase transition […]
Trapping light with disorder
Phys.org October 5, 2021 A random laser has many degrees of freedom that are not available in conventional cavity lasers. Based on this discovery, an international team of researchers (Israel, France) showed that laser emission can be simply controlled by shaping the pump profile that provides the gain inside the scattering medium. This is done optically with total flexibility. They found that selective excitation significantly reduces the lasing threshold, while lasing efficiency is greatly improved. Their spatial locations are critical to boost laser power efficiency. By efficiently suppressing the spatial hole burning effect, they could turn on the optimally outcoupled random […]