Reviews & Analysis

Beating the diffraction limit of light is not a simple task. However, as reported at the recent Focus on Microscopy conference in Japan, solutions are being found.

A speckle beam of light breaks up into small fragments as it propagates in a standard self-focusing nonlinear material. Now, by exploiting the non-local thermal response of a material, it is possible to trap a speckle beam in a self-induced waveguide.

Diffraction gratings have a long history, but researchers in Sweden have now come up with a new method for producing one- and two-dimensional grating patterns. The approach could be useful for fabricating complicated nanostructures and optical devices.

The use of nanostructured gold substrates is now allowing optical tweezers to exploit plasmonics and confine nanoparticles to ever smaller dimensions.

Carbon nanotubes possess unique properties that make them potentially useful in many applications in optoelectronics. This review describes the fundamental optical behaviour of carbon nanotubes as well as their opportunities for light generation and detection, and photovoltaic energy generation.

Optical antennas are the short-wavelength equivalent of the common radiofrequency structures. Taking this analogy one step further, the design concepts of radiofrequency lumped circuit elements can effectively be transplanted to optical wavelengths.

The ability to tune the resonant frequency of a metamaterial in the terahertz region will help to overcome some of the limitations of customary designs demonstrated so far. The result could be a new breed of active, frequency-agile devices that are controlled by light.

Researchers in Germany have shown that an ultrafast electron beam can be used to probe the dynamics of laser-generated plasmas with picosecond resolution.

By making use of polarization control, researchers have achieved a record 100-nm resolution when imaging buried transistors in an integrated circuit.

The ability to distinguish how many photons comprise a particular state of light leads to significant benefits in practical quantum information processing and quantum cryptography. Superconducting nanostructures provide an effective solution at telecom wavelengths.

Ceramic lasers look poised to make an impact in photonics thanks to the tantalizing possibilities of high output power, ultrashort-pulse generation and cost-effective production.

Optical antennas are able to concentrate light on a scale much smaller then the wavelength. By using the probe of an atomic force microscope, it is possible to manipulate a so-called bow-tie antenna, thereby tuning its optical response.

Two-photon emission has now been observed from an electrically pumped semiconductor. The process, which involves the simultaneous generation of correlated photons, could have important implications for quantum information technology.

How black is black? An ideally black material would absorb light perfectly at all angles for all wavelengths. Using arrays of carbon nanotubes, researchers based in New York have now engineered a metamaterial that constitutes the darkest material ever made.

The use of inorganic charge transport layers has enabled the fabrication of bright, environmentally stable LEDs that are based on electrically pumped colloidal solutions of quantum dots.