Volume 8 Issue 1, January 2014

A new optical technique enables electron beam currents to be measured with a femtosecond temporal resolution.

DNA tethers guide the self-assembly of colloidal metal nanoparticles into three-dimensional optical metamaterials. The observation of epsilon-near-zero behaviour in nanoparticle-based materials indicates that bottom-up assembly may be a viable solution to current challenges in the manufacture of metamaterials.

Sustaining the ongoing revolution in optical microscopy will require gaining detailed insight into the optical fields in focal spots. Researchers have developed an elegant method for mapping the full electric vector field using just a metal nanosphere on a glass substrate.

Tuning the luminescence lifetimes of upconversion nanocrystals through lanthanide doping provides new opportunities for optical multiplexing in the time domain for applications in imaging and security marking.

This article reviews the underlying physical principles of radiation nanofocusing in metallic nanostructures, and the recent progress, future directions and potential applications of this subfield of nano-optics.

An easily implementable reconstruction scheme is demonstrated for determining the full vectorial amplitude and relative phase distributions of highly confined electromagnetic fields with subwavelength resolution from a single-scan measurement. This scheme will help improve microscopy and nanoscopy techniques.

Quasi-monoenergetic Compton X-rays tunable in the range ∼70 keV to >1 MeV are generated in a laser-driven scheme.

Control over the luminescence lifetimes of upconversion nanocrystals allows a new form of temporal multiplexing for imaging and data-storage applications.

The carrier-envelope phase of laser fields at metal tips can affect the generation and motion of strong-field emitted electrons. Observed variations in the width of plateau-like photoelectron spectra characteristic of the sub-cycle regime may lead to the control of coherent electron motion at metallic nanostructures on ultrashort lengths and timescales.

Simultaneous detection of electric and magnetic fields with a subwavelength resolution is achieved by a near-field scanning approach. Additionally, theoretical considerations provide guidelines for designing probes sensitive to specific desired combinations of electric- and magnetic-field components.

Clear evidence is presented for the origins of photocurrent generation in metallic and semiconducting carbon nanotubes — photocurrent is found to be mainly generated by photothermal and photovoltaic effects in metallic and semiconducting carbon nanotubes, respectively. This finding will enable the engineering of highly efficient carbon-based photodetectors and energy-harvesting devices.

An optical-field-driven streak camera for the temporal characterization (with potentially attosecond resolution) of ultrashort free-electron pulses at 25 keV is demonstrated. It involves intersecting an electron beam and a laser beam at a thin metal mirror.

An approach is demonstrated that allows the optical transmission matrix to be noninvasively measured over a large volume inside complex samples using a standard photoacoustic imaging set-up. This approach opens the way towards deep-tissue imaging and light delivery utilizing endogenous optical contrast.

Perpendicular photoswitching of the polarization plane of the output second-harmonic light is observed in a chiral spin-crossover assembly based on an iron-octacyanoniobate magnet. This photoswitching can be reversed by irradiating with blue or red light. It originates from alternate photoswitching between the crystallographic and magnetic contributions to second-harmonic generation.

The use of Raman spectroscopy for high-resolution optical imaging is severely limited by the inherent weakness of the Raman effect. Now, a giant resonant Raman effect is demonstrated from J-aggregated dye molecules encapsulated in single-walled carbon nanotubes, and it is used to realize multispectral Raman imaging.

Researchers realized a magnet that can optically switch the polarization plane of light by 90 degrees. Nature Photonics asked Shin-ichi Ohkoshi how his group achieved this feat.