Volume 12 Issue 6, June 2018

The electromagnetic instability associated with a dense, ultra-relativistic electron beam propagating in a thin conductor could offer a new approach to realizing ultra-bright sources of gamma-rays.

The polarization state of isolated attosecond pulses generated by high-order harmonic generation can now be manipulated at will. The development opens the door for a multitude of ultrafast experiments to investigate chiral media.

The generation of gamma-ray flashes by dense ultra-relativistic electron beams travelling across a millimetre-thickness solid conductor is theoretically investigated. Peak brilliance above 10²⁵ photons s⁻¹ mrad⁻² mm⁻² per 0.1% bandwidth is expected.

The Bloch–Siegert shift—a strong-field phenomenon that implies a failure of the rotating-wave approximation—is observed in the polariton dispersion diagram of a two-dimensional electron gas system inside a high-Q terahertz photonic crystal cavity.

The direct generation of mid-infrared optical frequency combs in the region 2.5–4.0 μm from a 1.55-μm conventional and compact erbium-fibre-based femtosecond laser is demonstrated via coherent dispersive wave generation in silicon nitride nanophotonic waveguides.

By sending few-microjoule single-cycle terahertz pulses to a segmented terahertz electron accelerator and manipulator, 70 MV m^–1 peak acceleration fields, 2 kT m^–1 focusing gradients, 140 µrad fs^–1 streaking gradient and bunch compression to 100 fs are achieved.

Biodegradable cellulose-based photonic and plasmonic architectures are fabricated via soft nanoimprinting lithography, and are used for structural colour generation, photoluminescence enhancement and as disposable surface-enhanced Raman scattering substrates.

Circularly polarized isolated extreme-ultraviolet pulses are generated by exploiting non-collinear high- harmonic generation driven by two counter-rotating few-cycle laser beams. The numerical simulation predicts a linear chirp of 330 attoseconds.

Surface treatment is shown to yield passivated perovskite films with very high quasi-Fermi level splitting and internal photoluminescence quantum efficiency, indicating that further improvements in the performance of perovskite optoelectronics should be feasible.

A microcavity exciton–polariton system based on aligned and packed single-walled carbon nanotubes exhibits ultrastrong coupling. The coupling strength is polarization sensitive. The record high value of vacuum Rabi splitting, 329 meV, is reported.

The combination of a spatial light modulator at the fibre input, real-time spectral feedback and a genetic algorithm optimization controls the nonlinear stimulated Raman scattering cascade and its interplay with four-wave mixing in multimode fibres.