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Condensed-matter provides attractive platforms to realize exotic particles, originally proposed in high-energy physics. Weyl semimetal (WSM) is a material in which low-energy collective excitations are governed by massless Weyl fermions,…

Mesoscale and Nanoscale Physics · Physics 2025-01-20 Amar Bharti

Landau-level spectroscopy, the optical analysis of electrons in materials subject to a strong magnetic field, is a versatile probe of the electronic band structure and has been successfully used in the identification of novel states of…

Mesoscale and Nanoscale Physics · Physics 2020-04-30 S. Polatkan , M. O. Goerbig , J. Wyzula , R. Kemmler , L. Z. Maulana , B. A. Piot , I. Crassee , A. Akrap , C. Shekhar , C. Felser , M. Dressel , A. V. Pronin , M. Orlita

An experimental evidence of subwavelength imaging with a "lens", which is a uniaxial negative permittivity wire medium slab, is reported. The slab is formed by gratings of long thin parallel conducting cylinders. Taking into account the…

In the presence of strong magnetic fields the electronic bandstructure of graphene drastically changes. The Dirac cone collapses into discrete non-equidistant Landau levels, which can be externally tuned by changing the magnetic field. In…

Mesoscale and Nanoscale Physics · Physics 2017-07-26 Samuel Brem , Florian Wendler , Ermin Malic

Dye-doped hybrid silicate/titanium nanofilms on the glass substrate in the structure of asymmetrical waveguides were studied as the laser system. The spatial and spectral features of laser oscillation of genuine and hollow waveguides were…

Optics · Physics 2018-08-09 E. A. Tikhonov , V. P. Yashchuk , G. M. Telbiz

Context: Some stellar objects exhibit very narrow spectral lines in the visible range additional to their blackbody radiation. Natural lasing has been suggested as a mechanism to explain narrow lines in Wolf-Rayet stars. However, the…

Instrumentation and Methods for Astrophysics · Physics 2017-05-26 Peng Kian Tan , Christian Kurtsiefer

Self-mode-locking has become an emerging path to the generation of ultrashort pulses with vertical-external-cavity surface-emitting lasers. In our work, a strong Kerr nonlinearity that is so far assumed to give rise to mode-locked operation…

Single-mode operation is a desirable but elusive property for lasers operating at high pump powers. Typically, single-mode lasing is attainable close to threshold, but increasing the pump power gives rise to multiple lasing peaks due to…

Optics · Physics 2022-08-02 B. F. Zhu , Q. Wang , D. Leykam , H. R. Xue , Q. J. Wang , Y. D. Chong

We propose a class of spectral singularities that are sensitive to the direction of excitation and are arising in nonlinear systems with broken parity symmetry. These spectral singularities are sensitive to the direction of the incident…

Optics · Physics 2021-05-05 Hamidreza Ramezani

Employing high-pressure infrared spectroscopy we unveil the Weyl semimetal phase of elemental Te and its topological properties. The linear frequency dependence of the optical conductivity provides clear evidence for metallization of…

Mesoscale and Nanoscale Physics · Physics 2020-03-31 Diego Rodriguez , Alexander A. Tsirlin , Tobias Biesner , Teppei Ueno , Takeshi Takahashi , Kaya Kobayashi , Martin Dressel , Ece Uykur

Superlattices (SLs) in monolayer and bilayer graphene, formed by spatially periodic potential variations, lead to a modified bandstructure with extra finite-energy and zero-energy Dirac fermions with tunable anisotropic velocities. We…

Mesoscale and Nanoscale Physics · Physics 2012-05-14 Si Wu , Matthew Killi , Arun Paramekanti

Naturally or artificially stacking extra layers on single layer graphene (SLG) forms few-layer graphene (FLG), which has attracted tremendous attention owing to its exceptional properties inherited from SLG and new features generated by…

Mesoscale and Nanoscale Physics · Physics 2015-07-03 Chunxiao Cong , Ting Yu

Exposure of metal surfaces to multiple ultrashort laser pulses under certain conditions leads to the formation of well-defined periodic surface structures. We show how the period of such structures in steel can be tuned over a wide range by…

Semiconducting transition metal dichalcogenides (TMDs) have gained significant attention as a gain medium for nanolasers, owing to their unique ability to be easily placed and stacked on virtually any substrate. However, the atomically thin…

Intense laser-driven nonlinear optical phenomena in two-dimensional (2D) nodal-line semimetals (NLS) exhibit complex mechanisms, particularly in the NbSi$_{x}$Te$_{2}$ material systems characterized by nonsymmorphic symmetry-protected band…

Optics · Physics 2025-08-25 Navdeep Rana , M. S. Mrudul , Amar Bharti , Sucharita Giri , Gopal Dixit

The recent discovery of the Lorentz symmetry-violating 'Type II' Weyl semimetal phase has renewed interest in the study of Weyl physics in condensed matter systems. However, tuning the exceptional properties of this novel state has remained…

Quantum Gases · Physics 2017-01-25 Kunal Shastri , Zhaoju Yang , Baile Zhang

Lasers can exhibit nonlinear and chaotic dynamics driven by the interaction of multiple lasing modes, and investigating the different scenarios of mode competition and bifurcations of their dynamics is of great interest on a fundamental…

Optics · Physics 2022-12-23 Stefan Bittner , Marc Sciamanna

A rate equation model describing the laser dynamics of general one or two dimensional vertical cavity surface emitting laser (vcsel) arrays is introduced. It is shown that the theory includes both the previous theory for edge emitting…

Optics · Physics 2009-10-30 Holger F. Hofmann , Ortwin Hess

Topological lasers are of growing interest as a way to achieve disorder-robust single mode lasing using arrays of coupled resonators. We study lasing in a two-dimensional coupled resonator lattice exhibiting transitions between trivial and…

Optics · Physics 2020-07-07 Sinan Gundogdu , Juzar Thingna , Daniel Leykam

Computer simulations with Synopsys' Sentaurus TCAD of opto-electrical characteristics of separate-confinement heterostructure laser based on AlGaAs are used as an example to study the role of the width and depth of Quantum Well (QW) active…

Materials Science · Physics 2011-12-02 Zbigniew Koziol