Volume 3 Issue 9, September 2009

How can entangled photons be put to good use? When will quantum computing become feasible? Nature Photonics spoke to Alain Aspect to find out.

A spectroscopic method that combines the accuracy of optical frequency combs with the rapid tuning of an external-cavity diode laser opens the door to fast, broadband spectral characterization.

New insights into the behaviour of radiative heat transfer at the nanoscale have now been made, thanks to highly precise measurements made using scanning probe microscopy.

The polarization of terahertz pulses emitted from a laser-generated plasma can be rotated at will by changing the relative delay between ultrashort red and blue excitation pulses. The result is a fast and convenient method of polarization control.

A new idea for 'freezing-out' unwanted losses in an atomic memory could make it possible to store light pulses on-chip for several minutes, increasing the capability of optical quantum computing.

The need for reliable mass-produced photonic crystal devices and the exciting potential of nanoscale optomechanics were both highlights of a recent meeting on integrated photonics in Hawaii, USA.

Solar cell technology and optical information storage could be the first applications to benefit from plasmonics.

Photoacoustic tomography (PAT) is probably the fastest-growing area of biomedical imaging technology, owing to its capacity for high-resolution sensing of rich optical contrast in vivo at depths beyond the optical transport mean free path (∼1 mm in human skin). Existing high-resolution optical imaging technologies, such as confocal microscopy and two-photon microscopy, have had a fundamental impact on biomedicine but cannot reach the penetration depths of PAT. By utilizing low ultrasonic scattering, PAT indirectly improves tissue transparency up to 1000-fold and consequently enables deeply penetrating functional and molecular imaging at high spatial resolution. Furthermore, PAT promises in vivo imaging at multiple length-scales; it can image subcellular organelles to organs with the same contrast origin — an important application in multiscale systems biology research.

An all-optical technique for cleaning and purifying crystals of congruent lithium niobate is demonstrated, whereby a moving light beam removes photoexcitable electrons from the illuminated region and thus improves the material's optical damage threshold. The benefits of the scheme are also demonstrated for both undoped and Fe-doped congruent lithium niobate.

Radiation transfer on the nanoscale across gaps varying between 30 nm and 2.5 µm is investigated experimentally. The enhancement of heat transfer by evanescent wave contributions may pave the way for the design of sub-micrometre nanoscale heaters and radiators.

Quantum optical memory protocols are currently limited to storage times in the millisecond range. A quantum optical data storage protocol that extends the storage time by several orders of magnitude is proposed. The method introduces an optical locking technique to the resonant Raman optical echo approach.

A streak camera for characterizing the ultrashort X-ray pulses produced by a free-electron laser is reported. The scheme has a single-shot capability, a resolution of a few femtoseconds and is expected to become a useful tool for X-ray metrology, including experiments involving time-resolved spectroscopy and imaging.

Spectroscopy that combines the accuracy of a frequency comb with the ease of use of a tunable, external cavity diode laser is demonstrated, enabling precise dispersion measurements of microresonator modes.

Maskless high-resolution patterning of structural colours is demonstrated using a new material called ‘M-Ink’. The period of the material is patterned magnetically and a photochemical process immobilizes the structure in a polymer network.

Cooling and stabilizing the temperature of optoelectronic devices, such as semiconductor diode lasers and photodetectors, is often important for optimizing their performance. Neil Savage looks at thermoelectric coolers based on the Peltier effect that are designed for this task.

Illumination of a congruent lithium niobate crystal with blue or green light can improve its optical damage threshold dramatically. Nature Photonics spoke to Karsten Buse, who explained that this could result in far cheaper nonlinear crystals for a wide variety of photonic applications.