Volume 6 Issue 6, June 2012

Ignorance and negligence are frequently causing solar cells to be mischaracterized, and invalid efficiency results have been reported in a number of journals. This problem can be greatly alleviated by employing a few simple precautions and guidelines.

Electronic implants have been used to restore visual function lost as a result of retinal degeneration. Combining subretinal high-pixel-density arrays with optically powered serial photovoltaic sensors may alleviate some of the difficulties associated with today's devices, which rely on implanted arrays and inductive coils.

Controlling the velocity of neutral particles is an experimental challenge, owing to their absence of charge. Scientists have now demonstrated a technique that can be used to accelerate neutral argon atoms by polarizing them in moving optical lattices.

Recent research shows that quantum-mechanical tunnelling through individual semiconductor quantum dots can be promoted or inhibited using a low-intensity focused laser beam. This phenomenon may be useful for low-level light detection or quantum information applications.

The full quantum description of an optical detector not only reveals how it operates at the most fundamental level but also promises new opportunities in quantum information processing.

Interrogation schemes based on quantum physics look set to push the data-handling capabilities of optical communication channels to new levels of performance.

Quantum plasmonics, Fano resonances, surface plasmon–polariton Airy beams and plasmon-enhanced Raman spectroscopy are some of the new aspects of plasmonics that are now being explored.

Exploiting the low spatial coherence of specifically designed random lasers, researchers demonstrate speckle-free full-field imaging in the regime of intense optical scattering. Their results show that the quality of images generated from random-laser illumination is superior to those generated from spatially coherent illumination.

Lasing in X-ray free-electron lasers is typically achieved by self-amplification of spontaneous emission, which is known to have non-ideal temporal coherence and suffer from beam fluctuations. Here researchers report lasing based on echo-enabled harmonic generation at the Shanghai Deep Ultraviolet free-electron laser facility.

By developing full quantum detector tomography, researchers simultaneously characterize the wave- and photon-number sensitivities of quantum-optical detectors to yield the largest ever parametrization in a quantum tomography experiment. The presented results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors.

Using only conventional semiconductor processing on a silicon wafer, researchers successfully fabricate an on-chip resonator with a record Q-factor of 875 million — around 20 times higher than previous results. They also demonstrate stimulated Brillouin lasers as an example application to emphasize the size control feature of the fabrication method and the ultrahigh-Q available from these resonators.

Researchers experimentally demonstrate the first joint-detection receiver capable of performing a joint measurement over pulse-position-modulation codewords. This result — the largest improvement over the standard quantum limit reported to date — is accomplished by using a conditional nulling receiver, which uses optimized-amplitude coherent pulse nulling, single-photon detection and quantum feedforward.

Researchers demonstrate a silicon nanowire photodetector whose gold electrical contacts render the device ‘invisible’. The wire and gold coating have opposing dipole moments that almost cancel each other out in the far-field. Although the net dipole moment is zero, a significant photocarrier population is generated in the wire.

Researchers accelerate neutral-charge atoms from rest to a speed of 191 m s⁻¹ over a distance of 10 µm in 70 ns. This method is applicable to many atomic and molecular species, including those without permanent electric or magnetic dipole moments, which is a requirement of some alternative techniques.

Researchers demonstrate, in both normal and degenerate rat retinas, a photovoltaic subretinal prosthesis in which the silicon photodiodes in each pixel receive power and data through pulsed near-infrared illumination.

Scientists employ a micromachining-based technology to achieve significant enhancements in light emission from highly strained germanium-on-insulator samples.

Zhentang Zhao from the Shanghai Institute of Applied Physics spoke with Nature Photonics about how he and his co-workers achieved first lasing in an echo-enabled harmonic generation free-electron laser.