Recent advances in engineered material technologies (e.g., photonic crystals, metamaterials, plasmonics, etc) provide valuable tools to control Cherenkov radiation. In all these approaches, however, the designed materials interact only with the particle velocity to affect Cherenkov radiation, while the influence of the particle trajectory is generally negligible. Here, we report on surface Dyakonov-Cherenkov radiation, i.e. the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal. This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory, e.g. we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction. Moreover, close to the Cherenkov threshold, such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors. These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform. The surface Dyakonov-Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification, but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.
本文研究了在散粒噪声存在下，在电磁波的动态衍射条件下，初始未调制的电子（正电子）束团通过晶体（天然或人工晶体）时产生的合作参量（准切伦科夫）辐射的特性。对人工晶体中的太赫兹合作辐射进行了详细的数值分析。在模拟中得到了200~MW $/$ cm $^2$以上的辐射强度。在两波和三波衍射的情况下，合作辐射的峰值强度发射在小角度和大角度粒子速度的电子束团中的粒子数的函数进行了研究。峰值辐射强度似乎单调增加，直到达到饱和。在饱和时，散粒噪声引起合作参量辐射强度的强烈波动。结果表明，辐射脉冲的持续时间可以远远长于粒子通过晶体的飞行时间。这使得一个彻底的实验研究的时间结构的合作参量辐射的电子束团与现代加速器。合作参量（准切伦科夫）辐射的复杂时间结构可以在所有光谱范围（X射线，光学，太赫兹和微波）的人工（电磁，光子）晶体中观察到。
The process of soliton Cherenkov radiation (also known as dispersive wave emission) in microresonator frequency combs plays a critical role in generating broadband and coherent microcomb spectra. Here, we report the observation of symmetry breaking in the group velocity of counter-propagating dissipative Kerr solitons, induced by polychromatic soliton Cherenkov radiation. Results show that in the presence of higher-order dispersion, the temporal arrangement of a multi-soliton state affects its group velocity, an effect which originates from the interference between multiple radiative tails emi…
We consider radiation generated by an electron travelling parallel to a planar rectangular silicon grating: Smith-Purcell radiation to the vacuum side, internal Smith-Purcell radiation into the dielectric, and Cherenkov radiation into the dielectric. Internal Smith-Purcell radiation dominates over the other two radiation mechanisms in the range where conventional Smith-Purcell radiation is forbidden. This observation may lead to improved design of contactless particle beam monitors.
Time- and frequency-domain study for electron beams penetrating dielectric nanospheres: fingerprints of Cherenkov and transition radiation
Max-Born-Institut（马克斯·玻恩研究所）；Humboldt-Universität zu Berlin, Institut für Physik, AG Theoretische Optik and Photonik（柏林洪堡大学物理学院理论光学与光子学组）；POLIMA—Center for Polariton-driven Light-Matter Interactions, University of Southern Denmark（南丹麦大学极化激元驱动光物质相互作用中心）；Danish Institute for Advanced Study, University of Southern Denmark（南丹麦大学丹麦高等研究院）
Electrically charged particles, moving faster than the speed of light in a medium, emit Cherenkov radiation. Theory predicts electric and magnetic dipoles to radiate as well, with a puzzling behavior for magnetic dipoles pointing in transversal direction [I. M. Frank, Izv. Akad. Nauk SSSR, Ser. Fiz. 6, 3 (1942)]. A discontinuous Cherenkov spectrum should appear at threshold, where the particle velocity matches the phase velocity of light. Here we deduce theoretically that light bullets [Y. Silberberg, Opt. Lett. 15, 1282 (1990)] emit an analogous radiation with exactly the same spectral discon…
A recent study [PRB 100, 075427 (2019)], finally, demonstrated plasmon-analog of refractive index enhancement in metal nanostructures, which has already been studied in atomic clouds for several decades. Here, we simply utilize this phenomenon for achieving continuously-tunable enhanced Cherenkov radiation in metal nanostructures. Beyond enabling Cherenkov radiation from slow-moving particles, or increasing its intensity, the phenomenon can be used in continuous-tuning the velocity cutoff of particles contributing to the Cherenkov radiation. More influentially, this allows a continuously-tunab…
With the flourishing development of nanophotonics, Cherenkov radiation pattern can be designed to achieve superior performance in particle detection by fine-tuning the properties of metamaterials such as photonic crystals (PCs) surrounding the swift particle. However, the radiation pattern can be sensitive to the geometry and material properties of PCs, such as periodicity, unit thickness, and dielectric fraction, making direct analysis and inverse design difficult. In this article, we propose a systematic method to analyze and design PC-based transition radiation, which is assisted by deep le…
Cherenkov radiation provides a valuable way to identify high energy particles in a wide momentum range, through the relation between the particle velocity and the Cherenkov angle. However, since the Cherenkov angle depends only on material's permittivity, the material unavoidably sets a fundamental limit to the momentum coverage and sensitivity of Cherenkov detectors. For example, Ring Imaging Cherenkov detectors must employ materials transparent to the frequency of interest as well as possessing permittivities close to unity to identify particles in the multi GeV range, and thus are often lim…
For waveguides with two separate regions of anomalous dispersion, it is possible to create a quasi-stable two-color solitary wave. In this paper we consider how those waves interact with dispersive radiation, both generation of Cherenkov radiation and scattering of incident dispersive waves. We derive the analytic resonance conditions and verify them through numeric experiments. We also report incident radiation driving the internal oscillations of the soliton during the scattering process in case of an intense incident radiation. We generalize the resonance conditions for the case of an oscil…
Cherenkov radiation is generally believed to be threshold-free in hyperbolic metamaterials owing to the extremely large photonic density of states in classical local framework. While recent advances in nonlocal and quantum effects extend our understanding of light-matter interactions in metallic nanostructures, the influence of nonlocality on threshold-free Cherenkov radiation still remains elusive. Here we theoretically demonstrate that the nonlocality provides an indispensable way to flexibly engineer Cherenkov thresholds in metallodielectric layered structures. Particularly, the nonlocality…
We propose to use Vavilov-Cherenkov (VC) and transition radiations as a source of twisted photons in a wide range of energies. The experimental setup to observe the orbital angular momentum of photons constituting those radiations is described. The radiation produced by relativistic electrons and ions in passing dielectric plates is considered. The experimental verification of the addition rule for the total angular momentum in the radiation of twisted photons by helically microbunched beams is proposed for VC and transition radiations. The parameters of the experiments are presented.
We study some observational signatures of nonlinearities of the electromagnetic field. First to all we show the vital role played by nonlinearities in triggering a material behavior of the vacuum with $(\varepsilon > 0, μ<0)$, which corresponds to a ferrimagnetic material. Secondly, the permittivity and susceptibility induced by nonlinearities are considered in order to obtain the refractive index via the dispersion relation for logarithmic electrodynamics. Finally, we consider the electromagnetic radiation produced by a moving charged particle interacting with a medium characterized by nonlin…
Cherenkov radiation (CR) generated by a charge moving through a hollow conical target made of dielectric material is analyzed. We consider two cases: the charge moves from the base of the cone to its top (``straight'' cone) or from the top to the base (``inverted'' cone). Unlike previous papers, a nonzero shift of the charge trajectory from the symmetry axis is taken into account which leads to generation of asymmetric CR. The most interesting effect is the phenomenon of ``Cherenkov spotlight'' which has been reported earlier for axially symmetric problems. This effect allows essential enhance…
Modern trends in beam-driven radiation sources involve interaction of Cherenkov wakefields with open-ended circular waveguide structures having complicated dielectric lining, with a three-layer dielectric capillary recently offered for reducing the radiation divergency being a representative example \cite{Jiang2020}. This paper presents rigorous approach allowing analytical description of electromagnetic processes occuring when the described structure is excited by single waveguide mode. In other words, corresponding canonical waveguide diffraction problem is considered in rigorous formulation…
Andrew and Erna Viterbi Department of Electrical Engineering, Technion, Israel Institute of Technology（以色列理工学院）；School of Electrical and Electronic Engineering, Nanyang Technological University（南洋理工大学）；Zhejiang University（浙江大学）
The optical responses of semiconducting transition metal dichalcogenides are dominated by excitons. Being able to strongly interact with light and other materials excitations, excitons in semiconductors are prototypes for investigating many-particle and strong-field physics, including exciton-exciton, exciton-photon, and exciton-phonon interactions. Strong exciton-photon interactions, in particular, can lead to the emergence of exciton-polariton hybrid quasiparticles with peculiar characteristics, and a tendency toward macroscopic and spontaneous coherence. Normally, far-field and near-field o…
