Article
Physics, Multidisciplinary
Fumiya Sekiguchi, Hideki Hirori, Go Yumoto, Ai Shimazaki, Tomoya Nakamura, Atsushi Wakamiya, Yoshihiko Kanemitsu
Summary: The impact of phonon excitations on the photoexcited carrier dynamics in lead-halide perovskite CH3NH3PbI3 was investigated, showing that strong terahertz excitation can prolong the cooling time of hot carriers. The results demonstrate that phonon excitation significantly perturbs the carrier relaxation dynamics in halide perovskites through the coupling between transverse- and longitudinal-optical phonons.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
Aizitiaili Abulikemu, Takumi Fukuda, Muneaki Hase
Summary: This study investigates the ultrafast dynamics of coherent phonons and phonon-polaritons in lithium niobate (LiNbO3) crystals. The coexistence of several coherent optical phonon modes and phonon-polariton E-modes is observed, and a time lag between the coherent optical phonon and phonon-polariton is discovered. The findings suggest a possible application of LiNbO3 for ultrafast electro-optic phonon modulators with bandwidths greater than 10 THz.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Multidisciplinary
Flavio Giorgianni, Mattia Udina, Tommaso Cea, Eugenio Paris, Marco Caputo, Milan Radovic, Larissa Boie, Joe Sakai, Christof W. Schneider, Steven Lee Johnson
Summary: This study demonstrates a new pathway for optically controlling Raman-active modes in a strongly-correlated metal through a terahertz field-driven nonlinear process.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Won Jin Choi, Sang Hyun Lee, Bum Chul Park, Nicholas A. Kotov
Summary: Chemical, physical, biological, and materials engineering disciplines use chiroptical spectroscopies to study asymmetry in molecules and particles. Electronic and vibrational circular dichroism are commonly used techniques for studying electronic and vibronic transitions. THz circular dichroism is becoming increasingly important for complex molecules and materials, but its methodology and hardware are less developed compared to other chiroptical spectroscopies.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Jessica S. Lemos, Elena Blundo, Antonio Polimeni, Marcos A. Pimenta, Ariete Righi
Summary: This work presents a resonance Raman study conducted on the domes of monolayer MoS2, using 23 different laser excitation energies. The study reveals the exciton-phonon interactions of specific phonons (A'(1), E', and LA) with different excitonic optical transitions in strained MoS2 domes. The results show that the out-of-plane A'(1) phonon mode is significantly enhanced by the indirect exciton I and the C exciton, while the in-plane E' mode is only enhanced by the C exciton. The 2LA Raman band is significantly enhanced by the indirect exciton I and the A (or B) exciton, but not by the C exciton.
Article
Nanoscience & Nanotechnology
Ziqi Li, Bo Peng, Miao-Ling Lin, Yu-Chen Leng, Bin Zhang, Chi Pang, Ping-Heng Tan, Bartomeu Monserrat, Feng Chen
Summary: Research shows that phonons driven by femtosecond lasers can be utilized to manipulate the excitonic properties of semiconductors at THz frequencies, combining ultralow frequency Raman spectroscopy to identify phonon mode-selective and electron-phonon interactions. Furthermore, different types of coherent phonon excitations can preferentially couple to different types of electronic excitations.
NPJ 2D MATERIALS AND APPLICATIONS
(2021)
Article
Nanoscience & Nanotechnology
Mingming Feng, Baoqing Zhang, Haotian Ling, Zihao Zhang, Yiming Wang, Yilin Wang, Xijian Zhang, Pingrang Hua, Qingpu Wang, Aimin Song, Yifei Zhang
Summary: This paper presents a device that combines metal and graphene materials to achieve significant phase modulation of surface plasmon polaritons (SPPs). The experiment demonstrates that the cut-off frequency and phase of SPPs can be modulated by changing the chemical potential of graphene, and the transmittance is also controlled.
Article
Materials Science, Multidisciplinary
Benjamin M. Janzen, Piero Mazzolini, Roland Gillen, Andreas Falkenstein, Manfred Martin, Hans Tornatzky, Janina Maultzsch, Oliver Bierwagen, Markus R. Wagner
Summary: The study investigates the phonon modes of beta-Ga2O3 in different oxygen isotope compositions and reveals that the substitution of oxygen isotopes affects the Raman frequencies. By conducting experiments and theoretical calculations, the study identifies the atomistic origin of Raman modes and presents a blueprint for future identification of different point defects in Ga2O3 using Raman spectroscopy.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Multidisciplinary Sciences
O. Yu Gorobtsov, L. Ponet, S. K. K. Patel, N. Hua, A. G. Shabalin, S. Hrkac, J. Wingert, D. Cela, J. M. Glownia, D. Zhu, R. Medapalli, M. Chollet, E. E. Fullerton, S. Artyukhin, O. G. Shpyrko, A. Singer
Summary: The study focuses on controlling and detecting intermediate vibrational states in spin density wave systems using photoexcitation and XFEL probe. It provides a new approach to dynamically control functional properties and manipulate quantum states in charge and spin order systems.
NATURE COMMUNICATIONS
(2021)
Article
Optics
M. Ptak, E. Tomaszewicz, R. M. Kowalski, P. Solarz, P. Ropuszynska-Robak, L. Macalik, J. Hanuza
Summary: Lead and praseodymium tungstate solid solution samples were synthesized with varying praseodymium concentrations. The IR and Raman spectra were analyzed, and absorption, emission, and excitation spectra were measured and studied. The luminescent behavior upon femtosecond excitation was also examined.
JOURNAL OF LUMINESCENCE
(2022)
Article
Multidisciplinary Sciences
Mikhail Yu Morozov, Vyacheslav V. Popov, Denis Fateev
Summary: The study introduces a concept of an electrically controllable plasmonic directional coupler of terahertz signal based on a dual grating gate, and calculates its characteristics. Excitation of plasmons using the grating gate provides effective coupling of incident electromagnetic waves to plasmons, with a transformation coefficient exceeding unity due to amplification of plasmons in the structure.
SCIENTIFIC REPORTS
(2021)
Article
Optics
Carlo Silvestri, Xiaoqiong Qi, Thomas Taimre, Aleksandar D. Rakie
Summary: This study presents a numerical simulation of the active harmonic mode locking (HML) of quantum cascade lasers (QCLs) in the terahertz (THz) spectral range. It investigates the impact of laser intrinsic parameters and rf injection on the characteristics of the generated harmonic pulses. The study shows that by optimizing the QCL gain bandwidth and introducing an unmodulated section, ultrashort second-order harmonic pulses with a duration of 2.5 ps can be achieved.
Article
Chemistry, Physical
Feng Zhang, Keisuke Tominaga, Michitoshi Hayashi, Masahiko Tani
Summary: The study used solid-state density functional theory to calculate the THz spectra of DL- and L-alanine, revealing their similarities and differences. Two critical aspects regarding the intensities of the THz bands were identified, showing that the THz normal modes are dominated by intermolecular translations and influenced by the polarization effect. These findings provide a deeper understanding of the spectral differences observed in the absorption spectra.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Instruments & Instrumentation
Xinting Liu, Bo-Han Li, Yu Liang, Wen Zeng, Huang Li, Chuanyao Zhou, Zefeng Ren, Xueming Yang
Summary: This article presents a method to generate narrowband picosecond second harmonic (SH) and fundamental frequency (FF) pulses with high-conversion efficiency from a Ti:sapphire femtosecond laser amplifier, and successfully amplifies the pulses through optimization of a nonlinear crystal and an optical parametric amplifier. Additionally, dual-wavelength output, useful for femtosecond stimulated Raman spectroscopy, was achieved.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Multidisciplinary Sciences
Thuc T. Mai, Kevin F. Garrity, Amber McCreary, Joshua Argo, Jeffrey R. Simpson, Vicky Doan-Nguyen, Rolando Valdes Aguilar, Angela R. Hight Walker
Summary: Magnetic excitations in van der Waals materials, particularly in the 2D limit, have been studied using temperature-dependent magnetoRaman spectroscopy. The researchers identified hybridization of two-magnon excitations with two phonons in manganese phosphorus triselenide, and constructed a model to explain the observations. This work demonstrates the strong hybridization between phonons and a two-magnon continuum, providing insight into interactions in 2D magnetic materials.
Article
Materials Science, Multidisciplinary
Nikolai Christian Passler, Andreas Hessler, Matthias Wuttig, Thomas Taubner, Alexander Paarmann
ADVANCED OPTICAL MATERIALS
(2020)
Article
Chemistry, Physical
Feifan Wang, Jue Wang, Sebastian F. Maehrlein, Yingzi Ma, Fang Liu, X. -Y. Zhu
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2020)
Review
Chemistry, Multidisciplinary
Feifan Wang, Yongping Fu, Mark E. Ziffer, Yanan Dai, Sebastian F. Maehrlein, X-Y Zhu
Summary: The article introduces the concept of ferroelectric large polarons, which efficiently screen electrons or holes by extended ordering of dipoles from symmetry-broken unit cells. It suggests that the ferroelectric large polaron may explain the exceptional optoelectronic properties of lead halide perovskites.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Lucas Huber, Sebastian F. Maehrlein, Feifan Wang, Yufeng Liu, X. -Y. Zhu
Summary: The ultrafast optical Kerr effect is commonly used to investigate structural dynamics and interactions of materials, with non-degenerate mixing schemes allowing for more accurate detection. Two-color experiments can reveal sources of temporal dynamics in the OKE signal, showing how birefringence in crystalline solids can entirely change the character of the signal.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
Sebastian F. Maehrlein, Prakriti P. Joshi, Lucas Huber, Feifan Wang, Marie Cherasse, Yufeng Liu, Dominik M. Juraschek, Edoardo Mosconi, Daniele Meggiolaro, Filippo De Angelis, X-Y Zhu
Summary: The study highlights the importance of understanding the contribution of organic cations and inorganic lattice to polarization in lead halide perovskites. It also reveals the role of nonlinear mixing in generating anisotropic light propagation and convoluted oscillatory polarization dynamics in these materials.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Chemistry, Physical
Feifan Wang, Lucas Huber, Sebastian F. Maehrlein, X-Y Zhu
Summary: The study quantified the optical anisotropy in single-crystal MAPbBr(3) using 2D optical Kerr effect spectroscopy, revealing a strong photon energy dependence near the band gap and significant changes in optical anisotropy across phase transitions. The research also demonstrated the tuning of optical anisotropy by alloyed Cs(x)MA(1-x)PbBr(3) perovskite crystals.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Physics, Applied
Richarda Niemann, Soeren Wasserroth, Guanyu Lu, Sandy Gewinner, Marco De Pas, Wieland Schoellkopf, Joshua D. Caldwell, Martin Wolf, Alexander Paarmann
Summary: In this work, super-resolution microscopy in the long-wave infrared range is demonstrated using IR-visible sum-frequency generation. Enhanced spatial resolution and differentiation of different polariton modes within nanostructures are achieved.
APPLIED PHYSICS LETTERS
(2022)
Article
Multidisciplinary Sciences
Nikolai C. Passler, Xiang Ni, Guangwei Hu, Joseph R. Matson, Giulia Carini, Martin Wolf, Mathias Schubert, Andrea Alu, Joshua D. Caldwell, Thomas G. Folland, Alexander Paarmann
Summary: The lattice symmetry of a crystal plays a crucial role in determining its physical properties. Low-symmetry crystals, especially those with extreme optical anisotropy, offer opportunities to control light propagation and polarization. In this study, monoclinic crystals are shown to support a new class of polaritons called hyperbolic shear polaritons, emerging due to shear phenomena in the dielectric response. These findings have implications for non-Hermitian and topological photonic states, and expand the design possibilities for compact photonic devices.
Article
Nanoscience & Nanotechnology
Mingze He, Thomas G. Folland, Jiahua Duan, Pablo Alonso-Gonzalez, Simone De Liberato, Alexander Paarmann, Joshua D. Caldwell
Summary: This Perspective briefly introduces the physics and theories of polariton anisotropy, reviews recently investigated anisotropic and two-dimensional materials, and discusses approaches toward realizing hybrid modes and identifying new materials. Based on the results from the past few years, outstanding challenges are highlighted, and promising paths to further explore the potential for polariton anisotropy and hybrid systems in future nanophotonic optical devices are outlined.
Article
Chemistry, Physical
Yanhua Yue, Giacomo Melani, Harald Kirsch, Alexander Paarmann, Peter Saalfrank, R. Kramer Campen, Yujin Tong
Summary: Different terminations of the alpha-Al2O3(0001) surface have been observed under different experimental conditions, leading to discrepancies in prior work. By studying the surface phonon modes, this study provides a novel probe of the interfacial hydrogen bonding structure.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Physics, Applied
Marcel Kohlmann, Christian Denker, Nikolai C. Passler, Jana Kredl, Martin Wolf, Markus Muenzenberg, Alexander Paarmann
Summary: In this study, we experimentally observed the enhancement of mid-infrared second-harmonic generation using grating-coupled surface phonon polaritons and discussed the design options for engineering the plasmon-phonon polariton hybridization. The polariton-enhanced effect in this geometry was found to be relatively low compared to other coupling methods.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Guangwei Hu, Weiliang Ma, Debo Hu, Jing Wu, Chunqi Zheng, Kaipeng Liu, Xudong Zhang, Xiang Ni, Jianing Chen, Xinliang Zhang, Qing Dai, Joshua D. Caldwell, Alexander Paarmann, Andrea Alu, Peining Li, Cheng-Wei Qiu
Summary: Various optical crystals with opposite permittivity components have been observed and characterized in the mid-infrared regime. These crystals possess hyperbolic polaritons with large-momenta optical modes and wave confinement, making them promising for nanophotonic on-chip technologies. Monoclinic CdWO4 crystals are shown to exhibit symmetry-broken hyperbolic phonon polaritons and offer new opportunities for polaritonic phenomena.
NATURE NANOTECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Xiang Ni, Giulia Carini, Weiliang Ma, Enrico Maria Renzi, Emanuele Galiffi, Soeren Wasserroth, Martin Wolf, Peining Li, Alexander Paarmann, Andrea Alu
Summary: A new form of leaky polaritons with lenticular dispersion contours, neither elliptical nor hyperbolic, is experimentally observed. These interface modes are strongly hybridized with propagating bulk states, enabling directional, long-range, sub-diffractive propagation at the interface. Despite their leaky nature, these leaky polaritons exhibit long modal lifetime and reveal opportunities arising from the interplay of extreme anisotropic responses and radiation leakage.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Yanhua Yue, Giacomo Melani, Harald Kirsch, Alexander Paarmann, Peter Saalfrank, Yujin Tong, R. Kramer Campen
Summary: This study investigated the surface phonon modes of differently terminated alpha-Al2O3(0001) surfaces in different environments using vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation. It was found that the surfaces do not interconvert under certain conditions, offering an explanation for the discrepancies in prior research and showing that surface phonon spectral response can be used as a novel probe of interfacial hydrogen bonding structure.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Nikolai Christian Passler, Mathieu Jeannin, Alexander Paarmann