Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThree-Dimensional Chiral MetaCrystals
72
0
0.0
(
0
)
Added by
Mariachiara Manoccio
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Fine control of the chiral light-matter interaction at the nanoscale, by exploiting designed metamaterial architecture, represents a cutting-edge craft in the field of biosensing, quantum and classic nanophotonics. Recently, artificially engineered 3D nanohelices have demonstrated programmable wide chiroptical properties by tuning materials and architecture, but fundamental diffractive aspects that are to the origin of chiral resonances still remain elusive. Here, we proposed a novel concept of three-dimensional chiral MetaCrystal, where the chiroptical properties are finely tuned by in-plane and out-of-plane diffractive coupling. Different chiral dipolar modes can be excited along the helix arms, generating far field optical resonances and radiation pattern with in-plane side lobes and suggesting that a combination of efficient dipole excitation and diffractive coupling matching controls the collective oscillations among the neighbor helices in the chiral MetaCrystal. This concept enables the tailorability of chiral properties in a broad spectral range for a plethora of forefront applications, since the proposed compact chiral MetaCrystal can be suitable for integration with quantum emitters and can open perspectives in novel schemes of enantiomeric detection.
rate research
Read More
In the last decade, symmetry-protected bound states in the continuum (BICs) have proven to be an important design principle for creating and enhancing devices reliant upon states with high quality (Q) factors, such as sensors, lasers, and those for harmonic generation. However, as we show, current implementations of symmetry-protected BICs in photonic crystal slabs can only be found at the center of the Brillouin zone and below the Bragg-diffraction limit, which fundamentally restricts their use to single-frequency applications. By 3D-micro printing a photonic crystal structure using two-photon polymerization, we demonstrate that this limitation can be overcome by altering the radiative environment surrounding the slab to be a three-dimensional photonic crystal. This allows for the protection of a line of BICs by embedding it in a symmetry bandgap of the crystal. Moreover, we experimentally verify that just a single layer of this photonic crystal environment is sufficient. This concept significantly expands the design freedom available for developing next-generation devices with high-Q states.
Arbitrary manipulation of broadband terahertz waves with flexible polarization shaping at the source has great potential in expanding real applications such as imaging, information encryption, and all-optically coherent control of terahertz nonlinear phenomena. Topological insulators featuring unique spin-momentum locked surface state have already exhibited very promising prospects in terahertz emission, detection and modulation, which may lay a foundation for future on-chip topological insulator-based terahertz systems. However, polarization shaped terahertz emission with prescribed manners of arbitrarily manipulated temporal evolution of the amplitude and electric-field vector direction based on topological insulators have not yet been explored. Here we systematically investigated the terahertz radiation from topological insulator Bi2Te3 nanofilms driven by femtosecond laser pulses, and successfully realized the generation of efficient chiral terahertz waves with controllable chirality, ellipticity, and principle axis. The convenient engineering of the chiral terahertz waves was interpreted by photogalvanic effect induced photocurrent, while the linearly polarized terahertz waves originated from linear photogalvanic effect induced shift currents. We believe our works not only help further understanding femtosecond coherent control of ultrafast spin currents in light-matter interaction but also provide an effective way to generate spin-polarized terahertz waves and accelerate the proliferation of twisting the terahertz waves at the source.
Magnetic skyrmions are topological quasiparticles in magnetic field. Until recently, as one of their photonic counterparts, Neel-type photonic skyrmion is discovered in surface plasmon polaritons. The deep-subwavelength features of the photonic skyrmions suggest their potentials in quantum technologies and data storage. So far, the Bloch-type photonic skyrmion has yet to be demonstrated in this brand new research field. Here, by exploiting the quantum spin Hall effect of a plasmonic optical vortex in multilayered structure, we predict the existence of photonic twisted-Neel- and Bloch-type skyrmions in chiral materials. Their chirality-dependent features can be considered as additional degrees-of-freedom for future chiral sensing, information processing and storage technologies. In particular, our findings enlarge the family of photonic skyrmions and reveal a remarkable resemblance of the feature of chiral materials in two seemingly distant fields: photonic skyrmions and magnetic skyrmions.
PbTe crystals have a soft transverse optical phonon mode in the terahertz frequency range, which is known to efficiently decay into heat-carrying acoustic phonons, resulting in anomalously low thermal conductivity. Here, we studied this phonon via polarization-dependent terahertz spectroscopy. We observed softening of this mode with decreasing temperature, indicative of incipient ferroelectricity, which we explain through a model including strong anharmonicity with a quartic displacement term. In magnetic fields up to 25T, the phonon mode split into two modes with opposite handedness, exhibiting circular dichroism. Their frequencies displayed Zeeman splitting together with an overall diamagnetic shift with increasing magnetic field. Using a group-theoretical approach, we demonstrate that these observations are results of magnetic field-induced morphic changes in the crystal symmetries through the Lorentz force exerted on the lattice ions. This study thus reveals a novel process of controlling phonon properties in a soft ionic lattice by a strong magnetic field.
The ability to experimentally map the three-dimensional structure and dynamics in bulk and patterned three-dimensional ferromagnets is essential both for understanding fundamental micromagnetic processes, as well as for investigating technologically-relevant micromagnets whose functions are connected to the presence and dynamics of fundamental micromagnetic structures, such as domain walls and vortices. Here, we demonstrate time-resolved magnetic laminography, a technique which offers access to the temporal evolution of a complex three-dimensional magnetic structure with nanoscale resolution. We image the dynamics of the complex three-dimensional magnetization state in a two-phase bulk magnet with a lateral spatial resolution of 50 nm, mapping the transition between domain wall precession and the dynamics of a uniform magnetic domain that is attributed to variations in the magnetization state across the phase boundary. The capability to probe three-dimensional magnetic structures with temporal resolution paves the way for the experimental investigation of novel functionalities arising from dynamic phenomena in bulk and three-dimensional patterned nanomagnets.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
