Articles in 2008

Scientists report a dual-wavelength quantum cascade laser that lases at wave factors k ≈ 0 and k ≈ 3.6 × 10⁸ m⁻¹. The finding may change the conventional idea that population inversion of lasing occurs only at k ≈ 0 and give ways on designing intersub-band devices with high k-space.

The application of a very strong magnetic field is experimentally demonstrated to enable operation of terahertz quantum cascade lasers at much higher temperatures than usual. Lasing at a frequency of 3 THz is reported at up to 225 K when a field of 19.3 T is applied. The results validate theoretical predictions that quantum confinement is a route towards room temperature operation.

The ability to modulate optical plasmons, propagating along a metal–dielectric waveguide, on the femtosecond time scale suggests that plasmons may be a suitable data carrier for future ultrasfast communication applications.

A monolithically grown Ge/Si avalanche photodetectors (APD) with a gain–bandwidth product of 340 GHz, the highest value for any APDs operating at 1,300 nm, and a sensitivity equivalent to commercially available III-V compound APDs is reported. The excellent performance paves the way to achieving low-cost, CMOS-based, Ge/Si APDs operating at data rates of 40 Gb s⁻¹ or higher, where the performance of III-V APDs is severely limited.

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.

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.

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

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.

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.

Climate change is going to force mankind to change the way it behaves, especially when it comes to energy consumption. Photonics could have a significant role to play.

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

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.

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

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.

Applications of microdisk lasers are intrinsically limited by their planar and isotropic emission. Now, by implementing appropriate diffraction gratings along the disk circumference, scientists present a vertically emitting terahertz quantum-cascade microdisk laser, shedding light on the fabrication of arrays of single-mode, highly collimated and powerful terahertz sources.