Volume 2 Issue 12, December 2008

A visit to a dental clinic could cease to be a fearsome experience. Duncan Graham-Rowe finds out how lasers can help dentists to provide patients with more comfortable and convenient dental treatments.

High-precision synchronization of remote timing sources is an increasing problem for large-area facilities, such as radio telescope arrays and particle accelerators. Femtosecond-pulse-train transfer by optical fibre may represent a solution.

By using laser frequency combs to stabilize astronomical spectrometers, it may be possible to better understand our expanding Universe.

The dynamics of chaotic lasers can be harnessed to create a random-number generator that works at an astonishing rate. Such a generator could be implemented to make storage and transfer of data more secure at very high speeds.

Coupled optical microresonators are one way of slowing down light. A new record has now been set for the length of these slow-light waveguides using an array of more than 100 photonic-crystal cavities.

The effect of spin on the trajectories of polarized light beams has now been experimentally observed, with results that agree with the predictions of Berry phase theory.

Ultrashort laser pulses now make it possible to fabricate a wide range of biomaterials and implants ranging from cell scaffolds to artificial microvalves.

The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material — polycrystalline ceramic — can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

Random-number generators are important in digital information systems. However, the speed at which current sources operate is much slower than the typical data rates used in communication and computing. Chaos in semiconductor lasers might help to bridge the gap.

Femtosecond-scale synchronization using mode-locked lasers has been limited to periods of just a few minutes. Now it is shown that, by combining a number of laser techniques, sub-10-fs-precision synchronization of remote lasers and microwave sources is possible for more than 10 hours.

The ability to perform low-power, continuous-wave nonlinear optics, in particular four-wave mixing, is demonstrated in doped-silica-glass waveguide ring resonators. The device's low loss and ease of manufacture may make the approach suitable for nonlinear all-optical photonic integrated circuits.

Coupled optical resonators are one approach to slowing the propagation of light. An array of more than 100 such resonators has now been demonstrated using a photonic crystal. Such a structure can slow light down to below 1% of its speed in a vacuum.

The spin Hall effect, an interaction between particles because of their intrinsic spin, is a central tenet in the field of spintronics. The direct observation of an optical equivalent of the spin Hall effect is now reported.

A round-up of recent papers in the field of photonics published by the physical sciences division of the Nature Publishing Group.

The use of deformable mirrors to correct unwanted optical aberrations in real time is helping applications ranging from astronomy to biophotonics and data storage, reports Neil Savage.

Laser noise and chaos are unwanted elements in most circumstances. However, scientists have now learnt how to put them to good use to generate high-quality random bit sequences. Atsushi Uchida from Saitama University in Japan tells Nature Photonics how.