Phys.org August 30, 2023 To date research on metasurfaces has mainly focused on the full control of electromagnetic characteristics, including polarization, phase, amplitude, and even frequencies. Consequently, versatile possibilities of electromagnetic wave control have been achieved, yielding practical optical components such as metalenses, beam-steerers, metaholograms, and sensors. Researchers in South Korea focused on integrating the metasurfaces with other standard optical components for commercialization with miniaturization trends of optical devices. In this review they described and classified metasurface-integrated optical components, and subsequently discussed their promising applications with metasurface-integrated optical platforms including those of augmented/virtual reality, light detection and ranging, and sensors. […]
Tag Archives: Metamaterials
New method simplifies the construction process for complex materials
MIT News August 2, 2023 Cellular metamaterials are small scale, tileable structures that can be architected to exhibit many useful material properties. But their “architectures” vary widely making it difficult to explore them using existing representations. An international team of researchers (USA – MIT, Austria) created a technique to include many different building blocks of cellular metamaterials into one, unified graph-based representation using which engineers can quickly and easily model metamaterials, edit the structures, and simulate their properties. Their procedural graph succinctly represents the construction process for any structure using a simple skeleton annotated with spatially varying thickness. To express […]
Scientists presents a one-step laser synthesis method for fabricating wideband microwave absorption metamaterial
Phys.org July 13, 2023 Microwave absorption in radar stealth technology is faced with challenges in terms of its effectiveness in low-frequency regions. An international team of researchers (UK, Singapore) has developed a new laser-based method for producing an ultrawideband metamaterial-based microwave absorber with a highly uniform sheet resistance and negative magnetic permeability at resonant frequencies, which results in a wide bandwidth in the L- to S-band. The electrical sheet resistance uniformity was achieved with less than 5% deviation resulting in a microwave absorption coefficient between 97.2% and 97.7% within a 1.56–18.3 GHz bandwidth for incident angles of 0°–40°, and there […]
Physicists develop a metamaterial that can count
Phys.org July 3, 2023 Researchers in the Netherlands have designed irreversible metamaterials that count mechanical driving cycles and store the result into easily interpretable internal states. They extended the designs to aperiodic metamaterials that were sensitive to the order of different driving magnitudes and realized “lock and key” metamaterials that only reach a specific state for a given target driving sequence. The metamaterials were robust, scalable, and extendable, gave insight into the transient memories of complex media, and opened new routes towards smart sensing, soft robotics, and mechanical information processing. Video https://youtu.be/soO2OzbdRzU… read more. TECHNICAL ARTICLE
New research on self-locking light sources presents opportunities for quantum technologies
Nanowerk June 19, 2023 An international team of researchers (Argentina, Germany) demonstrated that light emitters with different resonance frequencies can asynchronously self-lock their relative energies by exchanging mechanical energy. They introduced polaromechanical metamaterials, two-dimensional arrays of μm-sized traps confining zero-dimensional light-matter polariton fluids and GHz phonons. A strong exciton-mediated polariton-phonon interaction induced a time-dependent inter-site polariton coupling J(t) with remarkable consequences for the dynamics. When locally perturbed by continuous wave optical excitation, a mechanical self-oscillation started and polaritons responded by locking the energy detuning between neighbor sites at integer multiples of the phonon energy showing asynchronous locking involving the polariton […]
Researchers discover new radiation effects in photonic time crystals
Phys.org April 26, 2023 Time metamaterials offer a great potential for wave manipulation. Researchers at the City University of New York explored the exotic wave dynamics of an anisotropic photonic time crystal (APTC) formed by an anisotropic medium whose optical properties are uniformly and periodically changed in time. Based on a temporal transfer matrix formalism, they showed that a stationary charge embedded in an APTC emits radiation, in contrast to the case of isotropic photonic time crystals, and its distribution in momentum space is controlled by the APTC band structure. According to the researchers their approach greatly extends the concept […]
Researchers show a new way to induce useful defects using invisible material properties
Nanowerk December 23, 2022 Researchers at the University of Illinois constructed a Dirac material consisting of a chain of magnetic-mechanical resonators and demonstrated that when any of these “atoms” was mechanically excited the excitation spread to the rest of the crystal, just like electrons injected into a semiconductor. After demonstrating that a completely uniform Dirac metamaterial does not allow mechanical excitations to pass through, they introduced a specific set of nonlinearities into the system. This new property added sensitivity to the level of the mechanical excitation and could subtly change the resonance energy of the magneto-mechanical atoms. With the right […]
Using machine learning to infer rules for designing complex mechanical metamaterials
Phys.org November 23, 2022 Combinatorial problems arising in puzzles, origami, and (meta) material design have rare sets of solutions, which define complex and sharply delineated boundaries in configuration space. The boundaries are difficult to capture with conventional statistical and numerical methods. Researchers in the Netherlands have shown that convolutional neural networks can learn to recognize these boundaries for combinatorial mechanical metamaterials, down to the finest detail, despite using heavily undersampled training sets, and can successfully generalize. According to the researchers even if machine learning is typically a “black box” approach, it can still be very valuable for exploring the design […]
Zero-index metamaterials offer new insights into the foundations of quantum mechanics
Phys.org April 27, 2022 Most theoretical derivations of fundamental radiative processes rely on energetic considerations and detailed balance equations, but not on momentum considerations. An international team of researchers (USA – Harvard University, University of Pennsylvania, Belgium, Spain, Denmark) re-examined the foundations of quantum physics from the perspective of momentum and explored what happens when the momentum of light is reduced to zero. They theoretically demonstrated that momentum recoil, transfer momentum from the field to the atom and Doppler shift are inhibited in NZI materials. Fundamental radiative processes inhibition is also explained due to those momentum considerations inside three-dimensional NZI […]
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 […]