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Within the last decade microscopic multiphase flows have gained broad interest. An exact understanding of the underlying hydrodynamic interrelations is the key for successful reactor layout and reaction control. To examine the local…

Fluid Dynamics · Physics 2020-02-14 Thorben Helmers , Philip Kemper , Ulrich Mießner , Jorg Thöming

Nonlinear terahertz (THz) spectroscopy relies on the interaction of matter with few-cycle THz pulses of electric field amplitudes up to megavolts/centimeter (MV/cm). In condensed-phase molecular systems, both resonant interactions with…

Chemical Physics · Physics 2021-12-08 Klaus Reimann , Michael Woerner , Thomas Elsaesser

Terahertz spectroscopy allows for identifying different isomers of materials, for drug discrimination as well as for detecting hazardous substances. As many dielectric materials used for packaging are transparent in the terahertz spectral…

Optics · Physics 2020-11-06 Mirco Kutas , Björn Haase , Jens Klier , Daniel Molter , Georg von Freymann

A compact terahertz (THz) polarimetric spectrometer and imaging system is demonstrated using polarization-sensitive frequency-selective surfaces (PS-FSS) and rapid, intensity-based detection. Real-time Stokes parameter extraction enables…

Interpretation of time-resolved spectroscopies such as transient absorption (TA) or two-dimensional (2D) spectroscopy often relies on the perturbative description of light-matter interaction. In many cases the third order of nonlinear…

Terahertz (THz) imaging has emerged as a promising technology in medical diagnostics due to its non-ionizing radiation and high sensitivity to water content. However, conventional THz imaging systems face limitations such as slow mechanical…

We show that degenerate nonlinear diffusion equations can be asymptotically obtained as a limit from a class of nonlocal partial differential equations. The nonlocal equations are obtained as gradient flows of interaction-like energies…

Analysis of PDEs · Mathematics 2023-10-12 José Antonio Carrillo , Antonio Esposito , Jeremy Sheung-Him Wu

Here, we present a novel microscopic technique for measuring wavelength-dependent three-dimensional (3-D) distributions of the refractive indices (RIs) of microscopic samples in the visible wavelengths. Employing 3-D quantitative phase…

Optics · Physics 2016-04-20 JaeHwang Jung , Kyoohyun Kim , Jonghee Yoon , YongKeun Park

Topological insulator films are promising materials for optoelectronics due to a strong optical absorption and a thickness dependent band gap of the topological surface states. They are superior candidates for photodetector applications in…

Mesoscale and Nanoscale Physics · Physics 2018-09-11 Mathias Rosdahl Brems , Jens Paaske , Anders Mathias Lunde , Morten Willatzen

We report extensive enhancement in the refractive index of artificially designed metamaterials by exploiting the deep subwavelength coupling in a free-standing, thin-film metal-dielectric-metal checkboard structure. A record high refractive…

Optics · Physics 2022-04-04 Leena Singh , Ranjan Singh , Weili Zhang

We analyze the optical pump-probe reflection and transmission coefficients when the photoinduced response depends nonlinearly on the incident pump intensity. Under these conditions, we expect the photoconductivity depth profile to change…

Strongly Correlated Electrons · Physics 2024-10-30 Leya Lopez , Derek G. Sahota , J. Steven Dodge

The characterization of a third order nonlinear integrated waveguide is reported for the first time by means of a top-hat Dispersive-Scan (D-Scan) technique, a temporal analog of the top-hat Z-Scan. With a single laser beam, and by carrying…

Optics · Physics 2017-10-11 Samuel Serna , Nicolas Dubreuil

In this work, the linear absorption spectra for periodic arrays of GaAs-GaAsAl quantum wells with different thicknesses, inside electromagnetic wave has been studied. The eigen energies and eigen functions are calculated by solving the…

Mesoscale and Nanoscale Physics · Physics 2019-09-26 Zahra Javidi , Mehdi Hosseini , Mohammad Javad Karimi

We have obtained spatially resolved spectra of Titan in the near-infrared J, H and K bands at a resolving power of ~5000 using the near-infrared integral field spectrometer (NIFS) on the Gemini North 8m telescope. Using recent data from the…

Earth and Planetary Astrophysics · Physics 2015-05-27 Jeremy Bailey , Linda Ahlsved , V. S. Meadows

The terahertz spectral regime, ranging from about 0.1 to 15 THz, is one of the least explored yet most technologically transformative spectral regions. One current challenge is to develop efficient and compact terahertz emitters/detectors…

Mesoscale and Nanoscale Physics · Physics 2019-03-12 Liang Luo , Ioannis Chatzakis , Jigang Wang , Fabian B. P. Niesler , Martin Wegener , Thomas Koschny , Costas M. Soukoulis

We present a possible interpretation for the increase of the angular diameter of the supergiants alf Ori (M1-2 Ia-Ibe) and alf Her (M5 Ib-II) from the K band to the 11 micron region and the high-resolution 11 micron spectra without any…

Astrophysics · Physics 2009-11-10 Keiichi Ohnaka

Spectroscopic ellipsometry is a powerful method with high surface sensitivity that can be used to monitor the growth of even sub-monolayer film. However, the analysis of ultrathin films is complicated by the correlation of the dielectric…

The detection of spatial or temporal variations in very thin samples has important applications in the biological sciences. For example, cellular membranes exhibit changes in lipid composition and order, which in turn modulate their…

Light-absorbing materials are widely used, and their optical properties are an important factor. Snell's law does not hold in materials that partially absorb light. Hence, the optical path in refraction is calculated from Maxwell's law. We…

Optics · Physics 2023-01-04 Shosuke Sasaki

Nonlinear optical methods are becoming ubiquitous in many areas of modern photonics. They are, however, often limited to a certain range of input parameters, such as pulse energy and average power, since restrictions arise from, for…