Free-electron resonance transition radiation via Brewster randomness

Proceedings of the National Academy of Sciences, Год журнала: 2025, Номер 122(6)

Опубликована: Фев. 5, 2025

Free-electron radiation, such as Cherenkov radiation and transition can generate light at arbitrary frequencies is fundamental to diverse applications, ranging from electron microscopy, spectroscopy, lasers, particle detectors. Generally, the features of free-electron are stochastic when electrons interact with random media. Counterintuitively, here, we reveal a type that has both its intensity directionality invariant specific sorts long-range structural randomness. Essentially, this invariance enabled by Brewster effect judiciously engineered phase coherence condition emitted light, namely induced electron’s penetration through layered aperiodic nanostructure interfere constructively angle. As such, each constituent layer thickness fulfills condition, there always emergence resonance At resonant angle, further find could be enhanced orders magnitude readily increasing interface number. The revealed via randomness may offer feasible route explore more enticing photonic applications driven free electrons, sources previously unreachable spectral regimes, optical frequency combs, detectors, lasers.

Язык: Английский

---

Low-Velocity-Favored Transition Radiation

Physical Review Letters, Год журнала: 2023, Номер 131(11)

Опубликована: Сен. 13, 2023

When a charged particle penetrates through an optical interface, photon emissions emerge-a phenomenon known as transition radiation. Being paramount to fundamental physics, radiation has enabled many applications from high-energy identification novel light sources. A rule of thumb in is that the intensity generally decreases with decrease velocity v; result, low-energy particles are not favored practice. Here, we find there exist situations where extremely low velocities (e.g., v/c<10^{-3}) exhibits comparable v/c=0.999), c speed free space. The implies high extraction efficiency particles, up 8 orders magnitude larger than particles. This exotic low-velocity-favored originates interference excited Ferrell-Berreman modes ultrathin epsilon-near-zero slab. Our findings may provide promising route toward design integrated sources based on electrons and specialized detectors for beyond-standard-model

Язык: Английский

---

Interfacial Cherenkov radiation from ultralow-energy electrons

Proceedings of the National Academy of Sciences, Год журнала: 2023, Номер 120(38)

Опубликована: Сен. 11, 2023

Cherenkov radiation occurs only when a charged particle moves with velocity exceeding the phase of light in that matter. This mechanism creates directional emission at wide range frequencies and could facilitate development on-chip sources except for hard-to-satisfy requirement high-energy particles. Creating from low-energy electrons has no momentum mismatch free space is still long-standing challenge. Here, we report to overcome this challenge by exploiting combined effect interfacial umklapp scattering, namely constructive interference sequential particle-interface interactions specially designed (umklapp) momentum-shifts. We find able create ultralow-energy electrons, kinetic energies down electron-volt scale. Due scattering excited high-momentum Bloch modes, resulting uniquely featured spatially separated apexes its wave cone group cone.

Язык: Английский

---

Superscattering of light: fundamentals and applications

Reports on Progress in Physics, Год журнала: 2024, Номер 87(12), С. 126401 - 126401

Опубликована: Ноя. 5, 2024

Abstract Superscattering, theoretically predicted in 2010 and experimentally observed 2019, is an exotic scattering phenomenon of light from subwavelength nanostructures. In principle, superscattering allows for arbitrarily large total cross section, due to the degenerate resonance eigenmodes or channels. Consequently, section a superscatterer can be significantly enhanced, far exceeding so-called single-channel limit. Superscattering offers unique avenue enhancing light–matter interactions enable numerous practical applications, ranging sensing, trapping, bioimaging, communications optoelectronics. This paper provides comprehensive review recent progress developments light, with specific focus on elucidating its theoretical origins, experimental observations, manipulations. Moreover, we offer outlook future research directions superscattering, including potential realizations directional scattering-free plasmonic enhancement free-electron radiation Purcell effect via superscatterers, inelastic non-electromagnetic waves.

Язык: Английский

---

Dipolar Huygens–Kerker radiation for surface waves

Optics Letters, Год журнала: 2024, Номер 49(15), С. 4238 - 4238

Опубликована: Июль 10, 2024

Exotic dipolar radiation with zero light emission in one direction but maximal the opposite was envisioned by Huygens 1690, and it could emerge vacuum if ratio between source’s electric magnetic dipole moments fulfills Kerker condition as revealed 1983. Due to its intricate connection both principle condition, this phenomenon is suggested be termed Huygens–Kerker radiation, at moment, ratio. However, remains underexplored non-vacuum matters, inside which source locates, especially for surface waves. Here we find that of waves occur matters essentially featured same normalized pattern, closely related inclination factor appears Fresnel–Kirchhoff diffraction theory. Moreover, corresponding intrinsically determined phase velocity excited To specific, proportional transverse-magnetic becomes inversely transverse-electric

Язык: Английский

---

Antihyperbolic surface waves on hyperbolic metasurfaces

Physical review. A/Physical review, A, Год журнала: 2025, Номер 111(3)

Опубликована: Март 21, 2025

Язык: Английский

---

Scattering-free Plasmonic Brewster Effect via Metasurfaces

ACS Photonics, Год журнала: 2025, Номер unknown

Опубликована: Март 30, 2025

The Brewster effect, dating back to the pioneering work of Sir David in 1815, offers a crucial route achieve 100% energy conversion between incident and transmitted propagating waves at an optical interface is fundamental importance many practical applications, such as polarization filtering, beam steering, broadband angular selectivity. However, whether effect surface can be implemented without involvement negative-permittivity or negative-permeability materials remains elusive. This due formidable challenge fully suppress both parasitic scattering into reflection under incidence waves. Here, we reveal feasible scattering-free plasmonic via isotropic metasurfaces, along with usage positive-permittivity positive-permeability metamaterials anisotropic magnetic responses. In essence, response judiciously designed waves, while facilitates full suppression supported by metasurfaces. Moreover, find that this metasurfaces further engineered occur for arbitrary angles, giving rise exotic phenomenon all-angle effect.

Язык: Английский

---

A gain route to reversed Cherenkov radiation

Science Advances, Год журнала: 2025, Номер 11(14)

Опубликована: Апрель 4, 2025

In his landmark paper from 1968, Veselago showed that Cherenkov radiation can be reversed in materials with a negative index of refraction, inspiring substantial research into such what became one the cornerstone concepts field metamaterials. Following and ongoing investigations considered it impossible to occur homogeneous isotropic slab positive refractive index. Here, we break this long-held belief by finding emergence positive-index exploiting optical gain. We find precise conditions under which backward-propagating is maintained while forward-propagating suppressed. Counterintuitively, intensity angular spread made robust thickness. Under scenario, increasing gain could decrease increase spread.

Язык: Английский

---

Theoretical Framework of Smith-Purcell Radiation Based on Abraham’s Theory

Springer proceedings in physics, Год журнала: 2025, Номер unknown, С. 39 - 46

Опубликована: Янв. 1, 2025

Язык: Английский

---

Free electron emission in vacuum assisted by photonic time crystals

Journal of Physics D Applied Physics, Год журнала: 2024, Номер 57(31), С. 315112 - 315112

Опубликована: Май 2, 2024

Abstract The Cerenkov radiation and Smith–Purcell (SP) effect state that free electron emission occurs exclusively in dielectrics when the velocity of particles exceeds speed light medium or vicinity periodic gratings close to each other within a vacuum. We demonstrate electrons vacuum can also emit highly directional monochromatic waves they are proximity is periodically modulated temporally, suggesting existence temporal SP effect. momentum band gaps time-varying media, such as photonic time crystals (PTCs), create new pathways for injection external energy, allowing frequency, intensity, spatial distribution electromagnetic fields be controlled. Moreover, PTC substrate enables conversion localized evanescent into amplified, propagating plane only sensitive modulation which allows us observe utilize Cerenkov-like space. Our work presents significant opportunities utilization structures various fields, including particle identification, ultraweak signal detection, improved source design.

Язык: Английский

---