Article
Spectroscopy
Jiho Kim, Wooseop Lee, Hyeji Kim, Du Yeol Ryu, Hyungju Ahn, Boknam Chae
Summary: A non-invasive, image-based analytic method using scattering-type scanning near-field optical microscopy (s-SNOM) is proposed to evaluate the phase separation behavior of lamella-forming polymer films, and the influence of self-assembly processes on the spatial distribution of polymer components is investigated.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Engineering, Mechanical
Yongfa Zhang, Jiang Zheng, Fuhui Shen, Weijian Han, Sebastian Munstermann, Haoge Shou, Qing Liu
Summary: Casting pores in HPDC AM60 samples have different characteristics such as size, morphology, and position, leading to local stress concentration. Small pores show higher number frequency and sphericity, while large pores have lower number frequency and complex shapes. The study reveals the evolution of local stress/strain around pores during deformation and the impact of pore interactions on stress concentration.
ENGINEERING FAILURE ANALYSIS
(2021)
Article
Optics
Paul Kaufmann, Helen M. Chrzanowski, Aron Vanselow, Sven Ramelow
Summary: Mid-infrared spectroscopy is an important analytical technique that can be used for a variety of materials. However, there are technical limitations in this field, such as the large noise in mid-IR detectors and the complexity and cost of bright, broadband mid-IR light sources. In this study, we bypass these limitations by using non-degenerate, broadband photon pairs from spontaneous parametric down-conversion in a nonlinear interferometer. We demonstrate spectroscopy in the mid-IR using only a visible solid-state laser and a commercial near-infrared grating spectrometer. The results show short integration times, high signal-to-noise ratios, and high spectral resolution.
Article
Nanoscience & Nanotechnology
Jiho Kim, Jin-Kyun Lee, Boknam Chae, Jinho Ahn, Sangsul Lee
Summary: This article presents a technique of scattering-type scanning near-field optical microscopy (s-SNOM) as a chemical visualization technique for structural changes in photoresist thin films at the nanoscale. The technique combines scanning probe microscopy and Fourier transform infrared spectroscopy to achieve high-resolution chemical analysis. The results show that s-SNOM is capable of visualizing line and space patterns in hydrogen silsesquioxane films prior to pattern development, with comparable accuracy to other microscopy techniques such as AFM and scanning electron microscopy.
Article
Optics
Rakesh Arul, David-Benjamin Grys, Rohit Chikkaraddy, Niclas S. Mueller, Angelos Xomalis, Ermanno Miele, Tijmen G. Euser, Jeremy J. Baumberg
Summary: This study demonstrates a self-assembled gold nanoparticle multilayer that supports tunable collective plasmon-polariton resonances in the visible and infrared spectrum. The structure exhibits high stability and efficient light coupling, making it suitable for nanoscale Raman and infrared sensing applications.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Optics
Niels M. Israelsen, Peter John Rodrigo, Christian R. Petersen, Getinet Woyessa, Rasmus E. Hansen, Peter Tidemand-Lichtenberg, Christian Pedersen, Ole Bang
Summary: We report on mid-infrared optical coherence tomography (OCT) at 4 μm with an increased A-scan scan rate of 3 kHz, using collinear sum-frequency upconversion. Two spectral realizations are demonstrated with improved imaging speed and axial resolution, showing potential applications in sub-surface micro-mapping and real-time monitoring of CO2.
Article
Instruments & Instrumentation
Paris Blaisdell-Pijuan, Zhe Chen, Yiteng Zhang, Sankaran Sundaresan, Bruce Koel, Claire Gmachl
Summary: The use of mid-infrared light to excite gas-phase reactants in heterogeneous catalytic processes can enhance energy efficiency, but close coupling between light-excited molecules and the catalyst is a primary challenge. By combining directional hemispherical measurements with in-line transmission measurements, it is possible to directly measure the scattered light signal, which is crucial for studying scattering behavior.
APPLIED SPECTROSCOPY
(2021)
Article
Polymer Science
Marcin K. Heljak, Ewa Kijenska-Gawronska, Adrian Chlanda, Maciej Lojkowski, Jakub Jaroszewicz, Carmelo de Maria, Giovanni Vozzi, Wojciech Swieszkowski
Summary: This paper presents a novel approach to mechanical modeling of ultrafine electrospun networks using high-resolution microscopy and computational methods. The accuracy and reliability of the morphology data extracted from X-ray microtomography, as well as the numerical analysis, have been successfully demonstrated. The methodology enables analysis of potential factors affecting the mechanical properties of electrospun structures, providing insights for future research in this area.
Article
Engineering, Mechanical
Vahab B. Narouie, Henning Wessels, Ulrich Roemer
Summary: Nowadays, techniques such as electronic speckle pattern interferometry and digital image correlation are used to measure strain and displacement. However, these measurement devices can only access some parts of the area of interest. To overcome this limitation, a fundamental task in structural health monitoring is to infer full-field displacements and mechanical stress from sparse measurements. The statistical Finite Element Method (statFEM) provides a computationally efficient approach to achieve this by calibrating the parameters of a given constitutive model and updating the displacement prior to fit the measurement data. This paper presents two contributions to the existing statFEM approach: the use of a non-intrusive polynomial chaos method to compute the prior and the examination of the influence of prior material models on the updated solution.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Chemistry, Physical
Yu-Jiao Xia-Hou, Xu-Cheng Li, En-Ming You, Hong-Peng He, Jun Yi, Jun-Rong Zheng, Hai-Long Wang, Hai-Xin Lin, Zhong-Qun Tian
Summary: A novel method using manganese oxide powder-assisted short time heating chemical vapor deposition was developed for growing high-quality and continuous graphene on non-planar and amorphous dielectric probe surfaces. The resulting graphene-coated dielectric probes exhibit significant improvement in IR reflectance and near-field light scattering compared to probes without continuous graphene coating. These graphene-coated probes show promising applications in nanoIR sensing based on AFM-IR spectroscopy and IR s-SNOM principles, and also provide a solution for growing high-quality graphene on non-planar dielectric surfaces needed in integrated circuits and other fields.
Article
Chemistry, Multidisciplinary
Inaki Lopez Garcia, Mario Siciliani de Cumis, Davide Mazzotti, Iacopo Galli, Pablo Cancio Pastor, Paolo De Natale
Summary: Theoretical modeling and experimental characterization of silicon nitride multilayer waveguides from visible to mid-infrared spectral regions were conducted, showing excellent waveguiding behavior with low losses in the infrared range.
APPLIED SCIENCES-BASEL
(2021)
Article
Multidisciplinary Sciences
Alexander Ebner, Paul Gattinger, Ivan Zorin, Lukas Krainer, Christian Rankl, Markus Brandstetter
Summary: In this study, a wide-field hyperspectral mid-infrared microscope based on multidimensional single-pixel imaging was demonstrated. The microscope utilized a high brightness MIR supercontinuum source for sample illumination and a single micro-opto-electro-mechanical digital micromirror device (DMD) for spatial and spectral differentiation. The DMD served the purpose of masking captured scenes and dispersing the projected field for wavelength selection without additional optical elements. The microscope's imaging and spectral capabilities were characterized, achieving high spatial and spectral resolutions. Label-free chemical imaging and examination of polymer compounds and red blood cells were successfully demonstrated. The design showed improved sample throughput in MIR chemical and biomedical imaging with tunable field of view and adjustable spatial resolution.
SCIENTIFIC REPORTS
(2023)
Article
Environmental Sciences
Michele Martinazzo, Tiziano Maestri
Summary: This study presents a methodology for calculating spectrally resolved upwelling radiances in the presence of atmospheric diffusive layers. The algorithm, called MAMA, provides fast and accurate simulations over the longwave spectrum, particularly for optically thin scattering layers like cirrus clouds. The solution is obtained by simplifying the multiple-scattering term in the radiative transfer equation and introducing the angular back-scattering coefficient as a fundamental property of the layer.
Article
Computer Science, Software Engineering
Iwan Boksebeld, Amir Vaxman
Summary: We present a framework for representing face-based directional fields of an arbitrary piecewise-polynomial order. Our formulation bypasses the difficulty of constructing high-order non-conforming function spaces, and enables the utilization of higher-order finite elements for directional-field processing. This representation preserves the structure of the fields and demonstrates benefits in various applications.
ACM TRANSACTIONS ON GRAPHICS
(2022)
Article
Acoustics
Xi Zhang, Hongguang Li, Xie Zhao, Chunyue Liu, Qu Liu, Hanlin Xiong, Guang Meng
Summary: This study adopts the acoustic finite element method (FEM) and acoustic boundary element method (BEM) coupling method to model, calculate, and analyze the three-dimensional model of a segmented ring transducer, in order to overcome the shortcomings of traditional FEM and direct coupling methods. The results indicate that the proposed method is correct and effective, and can be used to comprehensively calculate the acoustic characteristics of the segmented ring transducer.
Article
Chemistry, Multidisciplinary
Shang-Jie Yu, Yue Jiang, John A. Roberts, Markus A. Huber, Helen Yao, Xinjian Shi, Hans A. Bechtel, Stephanie N. Gilbert Corder, Tony F. Heinz, Xiaolin Zheng, Jonathan A. Fan
Summary: This study introduces bottom-up-synthesized alpha-MoO3 structures as nanoscale phonon polaritonic systems that feature tailorable morphologies and crystal qualities consistent with bulk single crystals. Alpha-MoO3 nanoribbons serve as low-loss hyperbolic Fabry-Perot nanoresonators, showcasing high-performance and low-loss capabilities for infrared optical and optoelectronic applications.
Article
Chemistry, Multidisciplinary
Thomas Siday, Fabian Sandner, Samuel Brem, Martin Zizlsperger, Raul Perea-Causin, Felix Schiegl, Svenja Nerreter, Markus Plankl, Philipp Merkl, Fabian Mooshammer, Markus A. Huber, Ermin Malic, Rupert Huber
Summary: This study demonstrates the Mott transition from an exciton gas to an electron-hole plasma in two-dimensional transition metal dichalcogenides. Using ultrafast polarization nanoscopy, the researchers observed the transition of dark exciton recombination from monomolecular to bimolecular as the carrier density increased. Their results provide direct evidence of the strong inhomogeneity in stacked monolayers.
Article
Multidisciplinary Sciences
Shuai Zhang, Baichang Li, Xinzhong Chen, Francesco L. Ruta, Yinming Shao, Aaron J. Sternbach, A. S. McLeod, Zhiyuan Sun, Lin Xiong, S. L. Moore, Xinyi Xu, Wenjing Wu, Sara Shabani, Lin Zhou, Zhiying Wang, Fabian Mooshammer, Essance Ray, Nathan Wilson, P. J. Schuck, C. R. Dean, A. N. Pasupathy, Michal Lipson, Xiaodong Xu, Xiaoyang Zhu, A. J. Millis, Mengkun Liu, James C. Hone, D. N. Basov
Summary: Excitons play a dominant role in the optoelectronic properties of atomically thin semiconductors. In this study, the authors used a scanning near-field optical microscope (s-SNOM) to characterize the exciton spectra and complex dielectric function of 2D transition metal dichalcogenides with previously unattainable resolution. The results provide insights into the spatial dependence of excitons and pave the way for their manipulation at the nanoscale.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Wei Cui, Kashif Masud Awan, Rupert Huber, Ksenia Dolgaleva, Jean-Michel Menard
Summary: A broadband and sensitive time-resolved terahertz configuration based on noncollinear optical interactions has been proposed, which improves the efficiency of THz generation and detection in nonlinear crystals. Compared to a standard collinear scheme, the noncollinear configuration enhances the THz signal by over 400 times and increases the system's dynamic range by 30 dB at 3 THz frequency.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Fabian Mooshammer, Sanghoon Chae, Shuai Zhang, Yinming Shao, Siyuan Qiu, Anjaly Rajendran, Aaron J. Sternbach, Daniel J. Rizzo, Xiaoyang Zhu, P. James Schuck, James C. Hone, D. N. Basov
Summary: In this study, near-field imaging was used to resolve in-plane anisotropic waveguide modes in thin rhenium disulfide crystals, allowing for the determination of the complete anisotropic dielectric tensor. The results provide key insights into the optoelectronic properties of ReS2.
Article
Optics
Christian Meineke, Michael Prager, Johannes Hayes, Qiannan Wen, Lukas Zheyi Kastner, Dieter Schuh, Kilian Fritsch, Oleg Pronin, Markus Stein, Felix Schafer, Sangam Chatterjee, Mackillo Kira, Rupert Huber, Dominique Bougeard
Summary: This study presents a flexible and scalable scheme for generating strong phase-locked terahertz (THz) pulses based on shift currents. The measured THz waveforms exhibit short duration, high peak fields, and strongly asymmetric electric field transients, making them suitable for high-repetition-rate applications.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Physics, Multidisciplinary
M. Knorr, J. M. Manceau, J. Mornhinweg, J. Nespolo, G. Biasiol, N. L. Tran, M. Malerba, P. Goulain, X. Lafosse, M. Jeannin, M. Stefinger, I Carusotto, C. Lange, R. Colombelli, R. Huber
Summary: The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells were directly studied using a noncollinear pump-probe geometry with phase-stable midinfrared pulses. Selective excitation of the lower polariton at a frequency of similar to 25 THz and at a finite in-plane momentum k(parallel to) resulted in the emergence of a narrowband maximum in the probe reflectivity at k(parallel to) = 0. A quantum mechanical model identified the underlying microscopic process as stimulated coherent polariton-polariton scattering.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Maria T. Schlecht, Matthias Knorr, Christoph P. Schmid, Stefan Malzer, Rupert Huber, Heiko B. Weber
Summary: This study investigated diodes under intense mid-infrared light-field pulses, providing the possibility of establishing light-field-driven electronics based on their characteristics.
Article
Multidisciplinary Sciences
J. Freudenstein, M. Borsch, M. Meierhofer, D. Afanasiev, C. P. Schmid, F. Sandner, M. Liebich, A. Girnghuber, M. Knorr, M. Kira, R. Huber
Summary: The study uses multi-terahertz light fields to force electron-hole pairs onto closed trajectories and measures the delay between separation and recollision with subfemtosecond precision. It is found that strong Coulomb correlations shift the optimal timing of recollisions. Quantitative analysis using quantum-dynamic many-body computations provides insights into the dynamics.
Article
Optics
Xinyi Xu, Chiara Trovatello, Fabian Mooshammer, Yinming Shao, Shuai Zhang, Kaiyuan Yao, D. N. Basov, Giulio Cerullo, P. James Schuck
Summary: The study finds that 3R-MoS2 slabs exhibit similar conversion efficiencies as lithium niobate, but with much shorter propagation lengths; in addition, broadly tunable second-harmonic generation can be achieved from 3R-MoS2 in a waveguide geometry, revealing the coherence length in such a structure.
Article
Optics
Erika Cortese, Joshua Mornhinweg, Rupert Huber, Christoph Lange, Simone De Liberato
Summary: The achievement of large values of light-matter coupling in nanoengineered photonic structures can lead to multiple photonic resonances contributing to the final properties of the same hybrid polariton mode. We develop a general theory describing multi-mode light-matter coupling in systems of reduced dimensionality, and validate our theory's predictions against numerical electromagnetic simulations. Our study characterizes the spectral features and real-space shapes of electromagnetic fields associated with each polariton mode, highlighting the potential for tailored manipulation of subwavelength electromagnetic fields.
Proceedings Paper
Engineering, Electrical & Electronic
Fabian Mooshammer, Markus Plankl, Paulo E. Faria, Sanghoon Chae, Thomas Siday, Martin Zizlsperger, Fabian Sandner, Felix Schiegl, Shuai Zhang, Yinming Shao, Aaron Sternbach, Daniel J. Rizzo, Simon Maier, Markus A. Huber, Martin Gmitra, Jaroslav Fabian, Jessica L. Boland, Xiaoyang Zhu, P. James Schuck, James Hone, Tyler L. Cocker, D. N. Basov, Rupert Huber
Summary: This article introduces the application of tip-based nanoscopy techniques in studying the properties of van der Waals crystals. It includes the investigation of interlayer tunneling and recombination of electron-hole pairs using terahertz nanoscopy, as well as the study of anisotropic waveguide modes in biaxial vdW crystals.
QUANTUM SENSING AND NANO ELECTRONICS AND PHOTONICS XVIII
(2022)
Article
Materials Science, Multidisciplinary
E. Moench, S. O. Potashin, K. Lindner, I Yahniuk, L. E. Golub, V. Yu Kachorovskii, V. V. Bel'kov, R. Huber, K. Watanabe, T. Taniguchi, J. Eroms, D. Weiss, S. D. Ganichev
Summary: We report the observation of ratchet effect in bilayer graphene, where direct electric current is generated in response to external terahertz radiation due to the broken inversion symmetry caused by an asymmetric dual-grating gate potential. The ratchet current shows different frequency dependencies at high and low temperatures, decreasing as proportional to 1/omega 2 and 1/omega 6, respectively. The theory predicts that the frequency dependence of the ratchet current is sensitive to the ratio of electron-impurity and electron-electron scattering rates.