We present measurements and analysis of the reflection spectrum of white light from a highly birefringent porous silicon layer at different polarization states. We report an anomalous pattern in the spectrum of linearly polarized light at 45° with respect to the principal axes of the layer. This spectrum comprises a combination of two interference effects, namely the Fabry-Perot-type multiple-beam interference present in a simple thin film, and a two-wave interference caused by the beat of two combined orthogonally polarized waves propagating in the birefringent medium. We perform a Fourier analysis of the measured reflected spectra. This analysis furnishes a powerful tool in order to separate the two interference mechanisms and determine the degree of coherence of their superposition.
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http://dx.doi.org/10.1364/AO.54.010636 | DOI Listing |
Inorg Chem
February 2024
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, P. R. China.
Herein, we report the synthesis, crystal structure, and optical properties of a metal-free three-dimensional (3D) inorganic covalent framework ((Hen)[Si(BO)], named , where Hen is the abbreviation for ethanediamine). With the assistance of a tiny amount of F ions and the selection of SiO as Si sources, single crystals of can be successfully prepared under solvothermal conditions. The precise structure information on has been disclosed through both single-crystal X-ray diffraction (SCXRD) and low-dose high-resolution transmission electron microscopy (LD-HRTEM).
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2024
Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States.
Two-dimensional (2D) films of conjugated porous organic polymers (C-POPs) can translate the rich in-plane functionalities of conjugated frameworks into diverse optical and electronic applications while addressing the processability issues of their crystalline analogs for adaptable device architectures. However, the lack of facile single-step synthetic routes to obtain large-area high-quality films of 2D-C-POPs has limited their application possibilities so far. Here, we report the synthesis of four mechanically robust imine-linked 2D-C-POP free-standing films using a single-step fast condensation route that is scalable and tunable.
View Article and Find Full Text PDFNanoscale Adv
June 2023
Department of Materials, Imperial College London Exhibition Road SW7 2AZ UK
Imogolite nanotubes (INTs) form transparent aqueous liquid-crystalline solutions, with strong birefringence and X-ray scattering power. They provide an ideal model system for studying the assembly of one-dimensional nanomaterials into fibres, as well as offering interesting properties in their own right. Here, polarised optical microscopy is used to study the wet spinning of pure INTs into fibres, illustrating the influence of process variables during extrusion, coagulation, washing and drying on both structure and mechanical properties.
View Article and Find Full Text PDFIn this Letter, we report a dual-wavelength Mueller matrix imaging system for polarization phase unwrapping, allowing simultaneous acquisition of the polarization images at 633 nm and 870 nm. After phase unwrapping, the relative error of linear retardance is controlled to be 3% and the absolute error of birefringence orientation is about 6°. We first show that polarization phase wrapping occurs when the samples are thick or present obvious birefringence effects, and further analyze the effect of phase wrapping on anisotropy parameters via Monte Carlo simulations.
View Article and Find Full Text PDFNanomaterials (Basel)
October 2022
School of Natural Sciences and Mathematics, Ural Federal University, 620000 Ekaterinburg, Russia.
The inscription regimes and formation mechanisms of form-birefringent microstructures inside nano-porous fused silica by tightly focused 1030- and 515-nm ultrashort laser pulses of variable energy levels and pulsewidths in the sub-filamentary regime were explored. Energy-dispersion X-ray micro-spectroscopy and 3D scanning confocal Raman micro-spectroscopy revealed the micro-tracks compacted by the multi-shot laser exposure with the nanopores hydrodynamically driven on a microscale to their periphery. Nearly homogeneous polarimetrically acquired subwavelength-scale form-birefringence (refractive index modulation ~10) was simultaneously produced as birefringent nanogratings inside the microtracks of wavelength-, energy- and pulsewidth-dependent lengths, enabling the scaling of their total retardance for perspective phase-modulation nanophotonic applications.
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