In this paper, we proposed a flexible method for generating asymmetric chiro-optical fields. Different from most of the chiro-optical fields superimposed by vortex beams which are rotationally symmetric, the asymmetric chiro-optical field has a locally controllable orbital angular momentum (OAM) and polarization state. By using a helix phase plate (HPP) calculated based on coordinates transformation of the perfect vortex, the OAM controllability of a single chiro-optical field could be achieved. Then, by using the transformation matrix method, several discrete chiro-optical fields with different rotation angles and topological charges were stitched together as a multi-lobed chiro-optical field with asymmetric OAM on each side-lobe. Furthermore, we designed two HPPs that can be loaded into two spatial light modulators to modulate the polarization state of each side-lobe of the asymmetric chiro-optical field independently. The proposed asymmetric chiro-optical field breaks the characteristics of uniform OAM and polarization distribution of conventional chiro-optical fields, which may have potential applications in optical tweezers, communications, and enantiomer-selective sensing.
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http://dx.doi.org/10.1364/OE.449884 | DOI Listing |
ACS Photonics
January 2025
Cardiff University School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, United Kingdom.
The field of chiral nanoparticles is rapidly expanding, yet measuring the chirality of single nano-objects remains a challenging endeavor. Here, we report a technique to detect chiro-optical effects in single plasmonic nanoparticles by means of phase-sensitive polarization-resolved four-wave mixing interferometric microscopy. Beyond conventional circular dichroism, the method is sensitive to the particle polarizability, in amplitude and phase.
View Article and Find Full Text PDFNat Photonics
August 2024
Max-Born-Institut, Berlin, Germany.
The topological response of matter to electromagnetic fields is a highly demanded property in materials design and metrology due to its robustness against noise and decoherence, stimulating recent advances in ultrafast photonics. Embedding topological properties into the enantiosensitive optical response of chiral molecules could therefore enhance the efficiency and robustness of chiral optical discrimination. Here we achieve such a topological embedding by introducing the concept of chiral topological light-a light beam which displays chirality locally, with an azimuthal distribution of its handedness described globally by a topological charge.
View Article and Find Full Text PDFSoft Matter
September 2024
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli 140306, India.
Non-symmetrical cholesterol-based dimers have emerged as crucial materials in the field of liquid crystal research, owing to their remarkable ability to stabilize various exotic mesophases, including the blue phases (BPIII, BPII, BPI), cholesteric nematic (N*) phase, smectic blue phase (SmBP), twist grain boundary (TGB) phase, smectic A/smectic A* (SmA/SmA*) phase, and smectic C/smectic C* (SmC/SmC*) phase. These mesophases have garnered considerable attention due to their diverse applications in spatial light modulation, chiro-optical devices, optical switching, thermochromic materials, and more. In this study, we present the synthesis and comprehensive characterization of a series of non-symmetrical cholesterol-based bent-shaped dimers (1/12, 1/14, 1/16) in which the cholesterol unit is intricately linked to an aromatic mesogenic core through a flexible spacer.
View Article and Find Full Text PDFNanoscale
September 2024
Department SBAI, Sapienza University of Roma, Via A. Scarpa 14, I-00161 Rome, Italy.
Metasurfaces tailor electromagnetic confinement at the nanoscale and can be appropriately designed for polarization-dependent light-matter interactions. Adding the asymmetry degree to the desing allows for circular polarizations of opposite handedness to be differently absorbed or emitted, which is of interest in fields spanning from chiral sensing to flat optics. Here, we show that simple, low-cost asymmetric metasurfaces can control Stokes parameters in the transmitted far-field.
View Article and Find Full Text PDFSci Rep
July 2024
Department SBAI, Sapienza University of Roma, Via A. Scarpa 14, 00161, Rome, Italy.
Chirality, the lack of mirror symmetry, can be mimicked in nanophotonics and plasmonics by breaking the symmetry in light-nanostructure interaction. Here we report on versatile use of nanosphere lithography for the fabrication of low-cost metasurfaces, which exhibit broadband handedness- and angle-dependent extinction in the near-infrared range, thus offering extrinsic chiro-optical behavior. We measure wavelength and angle dependence of the extinction for four samples.
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