Volume 2 Issue 6, June 2008

The spaser is a proposed nanoscale source of optical fields that is being investigated in a number of leading laboratories around the world. If realized, spasers could find a wide range of applications, including nanoscale lithography, probing and microscopy.

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

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.

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.

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.

The ‘spaser’ (surface plasmon amplification by stimulated emission of radiation) is a relatively new and exciting concept analogous to the laser. It involves amplifying specific surface plasmon modes using a nanoscale device. Zheludev and co-workers extend this concept by suggesting that metamaterials could be used to create a lasing spaser, that is, a spaser that can emit light with high spatial coherence.

Mode–locked fibre lasers enable high–power yet very stable optical frequency combs, paving the way towards higher resolution spectroscopy. The power scalability of such fibre–based systems opens the possibility of frequency combs operating with average powers in excess of 10 kW.

We report the experimental observation of one- and two-dimensional grating patterns formed in a disordered metal-nanoparticle layer by a single light pulse. The phenomenon is attributed to interference effects between the incident light and waveguided modes. Such self-patterning behaviour could be useful for the fabrication of complex nanostructures and advanced photonic devices.

Optical tweezers are well known for being able to control and move microscopic objects with high precision using focused laser beams. Alexander Grigorenko and colleagues report three-dimensional tweezers based on coupled pairs of gold nanodots in standard tweezer set-ups, which offer improved trapping efficiencies and reduced trapping volumes. Their tweezers could pave the way to improved manipulation of fragile, tiny biological objects.

Incoherent optical spatial solitons are self-trapped beams with a multimodal structure that varies randomly in time. All incoherent solitons observed so far have been supported by nonlinearities with slow response times. Here, Segev and colleagues demonstrate such solitons in nonlinear media with fast (essentially instantaneous) response times and show that new physical features appear.

Optical crystals with a strong nonlinear response to light are important tools in photonics, enabling applications ranging from wavelength conversion to short-pulse generation. Neil Savage surveys some of the materials on offer and their uses.

Trapping objects using light is a well-known technique. But designing traps that are subwavelength in size is a less well-explored avenue. Nature Photonics spoke to Alexander Grigorenko about the potential benefits.