It is well known that control over the polarization of electromagnetic waves can be achieved by utilizing artificial anisotropic media such as metamaterials. However, most of the related research has been focused on time-invariant systems. Inspired by the concept of temporal boundaries, we propose a method to realize polarization conversion in real time by employing time-variant materials, whose permittivity or permeability switches between isotropic and anisotropic values. The criteria for complete polarization conversion are studied for several polarization angles, both analytically and numerically.Plasmonic hollow fibers are fabricated by coating silver-/ gold-alloyed nanoparticles (Ag-Au-ANPs) onto the inner walls of hollow fibers. In this Letter, the Ag-Au-ANPs were synthesized chemically and dissolved in acetone to prepare a colloidal solution, flowed subsequently through the hollow fiber multiple times so that a thin layer of colloidal Ag-Au-ANPs was produced on the inner wall. Annealing at 400°C enabled melting/aggregation of the metallic nanoparticles and consequent formation of closely arranged plasmonic nanostructures fixed solidly on the inner wall. A surface-enhanced Raman scattering (SERS) mechanism was thus established for the liquids flowing through the hollows.  https://www.selleckchem.com/products/Irinotecan-Hcl-Trihydrate-Campto.html  The SERS measurements show an enhancement factor >104 for such plasmonic hollow fibers in the direct detection of R6G/ethanol solutions. Confinement of the excitation laser energy inside the hollow space represents an additional contribution to the enhancement mechanism. This is a promising design for the direct on-site SERS detection of molecules in flowing liquids with low concentrations.We experimentally demonstrate magnetic wire in a coupled, cut-wire pair-based metasurface operating at the terahertz frequencies. A dominant transverse magnetic dipole (non-axial circulating conduction current) is excited in one of the plasmonic wires that constitute the coupled system, whereas the other wire remains electric. Despite having large asymmetry-induced strong radiation channels in such a metasurface, non-radiative current distributions are obtained as a direct consequence of interaction between the electric and magnetic wire(s). We demonstrate a versatile platform to transform an electric to a magnetic wire and vice-versa through asymmetry-induced polymorphic hybridization with potential applications in photonic/electrical integrated circuits.Manipulating polarization, phase, and amplitude simultaneously in real time is an ultimate pursuit of controlling light. Several types of controllable metasurfaces have been realized, but with either low transmission efficiencies or limited control over amplitude, polarization, and phase in real time. Here we present a weak oscillation theory dealing with a new, to the best of our knowledge, type of optical system consisting of many layers of artificial oscillators, with each layer weakly interacting with the external field. As an application of our theory, we demonstrate and simulate a graphene-based metasurface structure to show that the oscillator system could change the focal length by changing the bias voltages. The polarization state to focus can also be selected by the bias voltage. The weak oscillation theory provides a flexible method to control the intensity, phase, and polarization.Ptychography is a promising phase retrieval technique for label-free quantitative phase imaging. Recent advances in phase retrieval algorithms witnessed the development of spectral methods to accelerate gradient descent algorithms. Using spectral initializations on experimental data, for the first time, we report three times faster ptychographic reconstructions than with a standard gradient descent algorithm and improved resilience to noise. Coming at no additional computational cost compared to gradient-descent-based algorithms, spectral methods have the potential to be implemented in large-scale iterative ptychographic algorithms.Multispectral/hyperspectral fluorescence lifetime imaging microscopy (λFLIM) is a promising tool for studying functional and structural biological processes. The rich information content provided by a multidimensional dataset is often in contrast with the acquisition speed. In this work, we develop and experimentally demonstrate a wide-field λFLIM setup, based on a novel time-resolved 18×1 single-photon avalanche diode array detector working in a single-pixel camera scheme, which parallelizes the spectral detection, reducing measurement time. The proposed system, which implements a single-pixel camera with a compressive sensing scheme, represents an optimal microscopy framework towards the design of λFLIM setups.Reconfigurability is critical for the research fields in electromagnetics, mechanics, and acoustics, due to the controllability of functionalities. This Letter numerically and experimentally demonstrates an origami-based absorber with a reconfigurable bandwidth. The proposed structure provides four transformable models flat sheet, single-arch-folded, double-arch-folded, and U-shaped strips filled, corresponding to the performance of nearly no absorption, one-peak absorption, two-peak absorption, and ultra-broadband absorption (3.4-18 GHz), which clearly demonstrates the bandwidth-enhancement effect. In contrast with the traditional structural absorbers, the transformable flat sheet and U-shaped strips are obtained by three-dimensional printing, which exhibits an obvious superiority in prototype fabrication. These results provide a feasible strategy for energy dissipation and origami transformation.Dual frequency combs are emerging as new tools for spectroscopy and signal processing. The relative phase noise of the tone pairs determines the performance (e.g., signal-to-noise ratio) of the detected spectral components. Although previous research has shown that the signal quality generally degrades with an increase in frequency difference between tone pairs, the scaling of the relative phase noise of dual frequency comb systems has not been fully characterized. In this Letter, we model and characterize the phase noise of a coherent electro-optic dual frequency comb system. Our results show that at high offset frequencies, the phase noise is an incoherent sum of the timing phase noise of the two combs, multiplied by line number. At low offset frequencies, however, the phase noise scales more slowly due to the coherence of the common frequency reference.