Scientists create an ‘optical conveyor belt’ for quasiparticles

Phys.org  May 14, 2024 Periodic temporal modulation of Hamiltonians can induce geometrical and topological phenomena in the dynamics of quantum states. Using the interference between two lasers an international team of researchers (Japan, USA – industry, Singapore, Australia, Germany) demonstrated an off-resonant optical lattice for a polariton condensate with controllable potential depths and nearest-neighbour coupling strength. Temporal modulation was introduced via a gigahertz frequency detuning between pump lasers, creating a polariton ‘conveyor belt’. The breaking of time-reversal symmetry caused band structures to become non-reciprocal and acquired a universal tilt. The non-reciprocal tilting was connected to the non-trivial topology of the […]

‘Optical magic’: New flat glass enables optimal visual quality for augmented reality goggles

Phys.org  September 28, 2022 Augmented reality (AR) glass needs to be highly transparent over almost the entire visible spectrum. In traditional AR there is a tradeoff in terms of quality and brightness between the external scene and the contextual information you want to visualize. A team of researchers in the US (Columbia University, City University of New York) has demonstrated nonlocal dielectric metasurfaces in the near-infrared that offer both spatial and spectral control of light, realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies unaffected. This is made possible by quasi-bound state in the continuum encoded […]

Harnessing the dark side

Nanowerk  July 13, 2021 Optical singularities, which appear completely dark, typically occur when the phase of light with a specific wavelength, or color, is undefined. Researchers at Harvard University have developed a new way to control and shape optical singularities. The metasurface tilts the wavefront of light in a very precise manner over a surface so that the interference pattern of the transmitted light produces extended regions of darkness. Their approach allows precise engineering of dark regions with remarkably high contrast. Engineered singularities could be used to trap atoms in dark regions and improve super high-resolution imaging. As darkness has […]

Researchers achieve extreme-ultraviolet spectral compression by four-wave mixing

Phys.org  January 25, 2021 Nonlinear optical techniques have made it possible to change the color of light and modify its spectral bandwidth without compromising the intensity. However, nonlinear optical techniques are not readily available in the XUV region of the electromagnetic spectrum. Researchers in Germany have demonstrated a concept for efficient spectral compression by four-wave mixing exploiting a phase-matching scheme based on closely spaced resonances. They compressed broadband radiation in the 145–130 nm wavelength range into a narrow-bandwidth XUV pulse at 100.3 nm wavelength in the presence of a broadband near-infrared pulse in a krypton gas jet. The narrowband XUV pulses has […]

Light from inside the tunnel

Nanowerk  June 30, 2020 In their experiment researchers in Germany focused two ultrashort light pulses with different wavelengths and slightly different propagation directions onto a thin slab of glass. A time- and frequency-resolved analysis of the emerging light emission showed that the current associated with the quantum mechanical tunneling process itself creates an optical non-linearity. The findings significantly expand both the fundamental understanding of optical non-linearity in dielectric materials and its potential for applications in information processing and light-based material processing…read more. TECHNICAL ARTICLE

Researchers catch light in a funnel

Phys.org  March 27, 2020 Rather than being an unavoidable nuisance, non-Hermiticity can be precisely controlled and used for sophisticated applications. Researchers in Germany implemented a non-Hermitian photonic mesh lattice by tailoring the anisotropy of the inter-site coupling. The appearance of an interface results in a complete collapse of the entire eigenmode spectrum, leading to an exponential localization of all modes at the interface. Consequently, any light field within the lattice travels toward this interface, irrespective of its shape and input position. Based on this topological phenomenon, they demonstrated a highly efficient funnel for light. The light accumulation achieved by the […]

New way to control the phase of light using 2D materials

Science Daily  February 24, 2020 Little is known about the effect of doping on the optical properties of TMDs at wavelengths far from excitonic resonances, where the material is transparent and therefore could be leveraged in photonic circuits. A team of researchers in the US (Columbia University, North Carolina State University, University of Chicago) has demonstrated the strong electro refractive response of monolayer tungsten disulfide (WS2) at near-infrared wavelengths (deep in the transparency regime) by integrating it on silicon nitride photonic structures to enhance the light–matter interaction with the monolayer. They showed that the doping-induced phase change relative to change […]

Nanoscale manipulation of light leads to exciting new advancement

Eurekalert  October 11, 2019 Researchers at the University of New Mexico studied arrays composed of silver nanoparticles placed in a repeating pattern. When the arrays are illuminated with light, each of the particles produces a strong response, which, in turn, results in enormous collective behaviors if all the particles can interact with one another. This happens at certain wavelengths of incident light, which are determined by the interparticle spacing of the array, and can result in electric fields that are thousands, or even tens of thousands, of times that of the light shined on the array. The strength of this […]

Light can scatter from light, CERN physicists confirm

Physics World  August 14, 2019 The quantum electrodynamic process of photon–photon scattering has for the first time been confirmed experimentally to a high degree of certainty. CERN’s ATLAS collaboration, which involves hundreds of physicists from around the world, made the breakthrough after analysing a large dataset of candidate scattering events using a neural network. Their discovery could fuel new research into a variety of theories beyond the Standard Model of particle physics. The discoveries of the ATLAS collaboration could inform future studies aiming to confirm and constrain these theories, potentially allowing much-anticipated updates to the Standard Model…read more. Open Access […]

Light may increase magnetic memory speeds 1000 times, decrease electricity consumption

Phys.org  July 11, 2019 To reduce energy consumption in magnetic memory devices and improve their speeds, a team of researchers in the US (NIST, University of Colorado, University of Oregon) has developed a method that uses optics through localized surface plasmon resonances to couple light to nanomagnets and produce faster spintronic devices switching speeds and potential lower energy consumption. The method could ultimately lead to memory writing speeds that are 1,000 times faster than current ones…read more. TECHNICAL ARTICLE