Volume 3 Issue 4, April 2009

More than one-fifth of US electricity is used to power artificial lighting. Light-emitting diodes based on group III/nitride semiconductors are bringing about a revolution in energy-efficient lighting.

Self-organizing liquid crystals could spawn a new breed of extremely useful and cheap tunable lasers. Such lasers may ultimately prove to be useful for creating flat-screen displays with better colours, enhanced sensors and compact medical instruments. Duncan Graham-Rowe takes a closer look.

By using light to assist the recording process, hard disk drive capacity could potentially be increased by two orders of magnitude. The idea is to heat the magnetic medium locally, thus temporarily lowering its resistance to magnetic polarization.

Third-harmonic generation enhanced by slow-light pulses in a photonic crystal waveguide offers a way to generate green light emission from silicon.

Ultrafast all-optical computation with silicon photonic devices is still a dream. New research, which combines organic nonlinear polymers with silicon waveguides, is now bringing that dream closer to reality.

Imaging through linear media is straightforward, but light beams propagating through nonlinear media become heavily distorted, rendering all usual imaging techniques practically useless. Now, scientists have found a way to recover images transmitted through nonlinear media — by using back-propagation simulations.

The ability to harness the Faraday effect on a short timescale in an ensemble of hot atoms may prove useful as a read-out tool for quantum information based on microscale vapour cells.

Resonant optical cavities such as Fabry–Perot resonators or whispering-gallery structures are subject to radiation pressure pushing their reflecting 'walls' apart. Deformable optical cavities yield to this pressure, but in doing so they in turn affect the stored optical energy, resulting in an optical back-action. For such cavities the optics and the mechanics become strongly coupled, making them fascinating systems in which to explore theories of measurements at the quantum limit. Here we provide a summary of the current state of optomechanics of deformable optical cavities, identifying some of the most important recent developments in the field.

The use of slow light for enhancing a nonlinear optical process in a two-dimensional silicon photonic-crystal waveguide is demonstrated. More specifically, green emission by third-harmonic generation is obtained, highlighting yet another functionality of silicon photonics chips.

Imaging through a nonlinear medium can be difficult because signals distort as they propagate through it owing to intensity-dependent phase changes. Here, digital reconstruction of optical spatial beams propagating in a nonlinear medium is presented, which could help the understanding of coupled-wave dynamics and suggest new image-processing techniques.

A silicon–organic hybrid slot waveguide with a strong optical nonlinearity is demonstrated to perform ultrafast all-optical demultiplexing of high-bit-rate data streams. The approach could form the basis of compact high-speed optical processing units for future communication networks.

Using a near-field transducer with efficient optical energy transfer, researchers demonstrate proof-of-principle heat-assisted magnetic recording with multi-track data density of ∼375 Tb m⁻².

By applying a magnetic field to an atomic vapour, it is shown that the large bandwidth of off-resonance slow-light media can be combined with the Faraday effect to realize a high-bandwidth dispersive probe for atomic systems. This will open up the possibility of probing atomic dynamics on a nanosecond timescale.

Pulse measurement equipment is now easier to use than ever before, with many devices offering easy-to-align solutions and plug-and-play computer operation, reports Neil Savage.

Magnetic hard disk technology is approaching its limits. Nature Photonics spoke to William Challener, Ed Gage and Mark Re from Seagate about their demonstration of heat-assisted magnetic recording.