Volume 3 Issue 11, November 2009

Researchers at Stanford University and the Max Planck Institute for Polymer Research have demonstrated fluorescence enhancements ten times greater than previously demonstrated, by placing single fluorophores in an optical bowtie nano-antenna.

Stanford University researchers have demonstrated the potential of single SiC whiskers to function as narrowband infrared emitters that have controllable emission characteristics.

Controlling the transport of charge carriers between two semiconductor nanostructures using an acoustic wave yields a high-repetition-rate source of single photons with tunable emission energy.

Customizing the refractive index of wells and barriers in a periodic array of quantum wells yields a way to control the reflectivity and dispersion of an excitonic lattice. The result is a new method for slowing or modulating light.

Visual encryption, manipulation of terahertz waves and the improved surface-treatment of GaN crystals were all topics of discussion at this year's JSAP meeting in Toyama, Japan.

From humble beginnings, the Belgian company Xenics has grown to become one of the world's leading suppliers of short-wave infrared cameras outside the US. Nadya Anscombe finds out how the company has survived the economic crisis by changing its business strategy and continually developing its products.

Hyperspectral imaging, traditionally used for airborne remote sensing, is now becoming a valuable tool for in-line inspection and quality control.

With new laser sources and detectors coming onto the market, terahertz imaging is starting to become a valuable tool for non-destructive testing, process control and quality inspection.

Digital holographic microscopy's ability to reconstruct three-dimensional surface topography from a single measurement without the need for any scanning makes it extremely robust and immune to vibrations. Its applications range from bioimaging through to analysing micro-electromechanical systems devices and quality-assurance tasks.

Although the machine vision industry is being affected by the global recession, Mats Gökstorp, president of the European Machine Vision Association, explains to Nadya Anscombe why he is optimistic about the industry's future.

A natural quarter-wave retarder in the eye of a stomatopod is demonstrated to have an achromaticity in the visible wavelength regime that outperforms existing designs of synthetic optical retarders. The performance is shown to be due to compensatory birefringent effects that eliminate wavelength dependence, resulting in an almost constant retardation at 450–700 nm.

It is now possible to acoustically control the transfer of electrons and holes between a quantum well and a quantum dot by exploiting the moving piezoelectric potential modulation induced by an acoustic phonon. The effect has been used to demonstrate a high-frequency single-photon source with tunable emission energy, by acoustically transferring carriers to selected quantum dots.

Adding electron-withdrawing groups to the backbone of the polymer PBDTTT is shown to increase the open-circuit voltage of photovoltaic cells, resulting in a polymer solar-cell that has a certified power-conversion efficiency of 6.77%.

A 1,340-fold increase in single-molecule fluorescence has been observed from a lithographically fabricated gold bowtie nanoantenna — approximately an order of magnitude greater than that achieved in previous reports on such structures. The improvement results from an estimated ninefold increase in quantum efficiency, caused by enhanced absorption and an increased radiative emission rate.

Single SiC whiskers can be made into infrared emitters by thermal excitation. The broadband thermal emission is coupled to the electromagnetic resonances of the whisker, allowing relatively narrowband emission at infrared frequencies. The emission frequency can be tuned by adjusting the size of the whiskers.

So-called photonic-crystal-excitonic-lattice polaritons can be observed by coupling excitons and Bloch waves in a periodic arrangement of GaAs/AlGaAs quantum wells. The effect can be tuned by using an electric field. These hybrid states may allow slow-light-enhanced nonlinear effects and enable observation of macroscopic coherence phenomena in solid-state systems.

The discovery that the eye of a particular mantis shrimp has an achromatic quarter-waveplate that is superior to modern-day devices could be a source of inspiration to those designing optical components. Nature Photonics spoke to Nicholas Roberts, one of the researchers involved in the study.

Hyperspectral imaging is a powerful tool for remotely monitoring the health of vegetation as well as benefiting applications in process control and quality assurance.