A non-invasive method for measuring the refractive index, extinction coefficient and film thickness of absorptive thin films using spectral-domain optical coherent tomography is proposed, analyzed and experimentally demonstrated. Such an optical system employing a normal-incident beam of light exhibits a high spatial resolution. There are no mechanical moving parts involved for the measurement except the transversal scanning module for the measurement at various transversal locations. The method was experimentally demonstrated on two absorptive thin-film samples coated on transparent glass substrates. The refractive index and extinction coefficient spectra from 510 to 580 nm wavelength range and film thickness were simultaneously measured. The results are presented and discussed.
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http://dx.doi.org/10.1364/OE.22.005675 | DOI Listing |
J Fluoresc
January 2025
Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar, Andhra Pradesh, 522510, India.
In this work, the conventional melt quenching approach is used to synthesize the Pr doped NaF-BiO-BO-SiO (NBBS) glasses. The influence of Pr ions on their spectroscopic and structural characteristics in glass network is investigated. The amorphous nature of the samples has been amply verified by X-ray diffraction patterns.
View Article and Find Full Text PDFNanoscale
January 2025
Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
Two-dimensional materials with a combination of a moderate bandgap, highly anisotropic carrier mobility, and a planar structure are highly desirable for nanoelectronic devices. This study predicts a planar BeP monolayer with hexagonal symmetry that meets the aforementioned desirable criteria using the CALYPSO method and first-principles calculations. Calculations of electronic properties demonstrate that the hexagonal BeP monolayer is an intrinsic semiconductor with a direct band gap of approximately 0.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse, NY, USA.
In numerous applications from radio to optical frequencies including stealth and energy harvesting, there is a need to design electrically thin layers capable of perfectly absorbing electromagnetic waves over a wide bandwidth. However, a theoretical upper bound exists on the bandwidth-to-thickness ratio of metal-backed, passive, linear, and time-invariant absorbing layers. Absorbers developed to date, irrespective of their operational frequency range or material thickness, significantly underperform when compared to this upper bound, failing to exploit the full potential that passive, linear, and time-invariant systems can provide.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Department of Materials Science and Engineering, University of Maryland, College Park, MD, 20742, USA.
The optical modulation of ferroelectric polarization constitutes a transformative, non-contact strategy for the precise manipulation of ferroelectric properties, heralding advancements in optically stimulated ferroelectric devices. Despite its potential, progress in this domain is constrained by material limitations and the intricate nature of the underlying mechanisms. Recent studies have achieved efficient regulation of ferroelectric polarization and thermal conductivity in chiral ferroelectric thin films through the application of left- and right-handed circularly polarized light (LCP and RCP).
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Birck Nanotechnology Center and the School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
High heat fluxes in electronic devices must be effectively dissipated to prevent local hotspots, which are critical for long-term device reliability. In particular, advanced semiconductor packaging trends toward thin form factor products increase the need for understanding and improving in-plane conduction heat spreading in anisotropic materials. The 2D laser-based Ångstrom method, an extension of traditional Ångstrom and lock-in thermography techniques, measures in-plane thermal properties of anisotropic sheet-like materials.
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