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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.
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.
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.
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.
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.
A waveguide–integrated GeSi electro-absorption modulator on silicon with an ultra-low energy consumption of 50 fJ–1bit is presented. Operating in the spectral range of 1539—1553 nm, the CMOS–compatible device has an active area of 30 µm2 and is anticipated to be useful for future communication systems based on large–scale electronic–photonic integration on silicon.
Two-photon excitation is attractive for photodynamic therapy as it potentially allows deeper penetration within biological tissue and targeting with better precision. However, two-photon cross-sections of light-sensitive drugs are typically small, which has until now limited their practical utility. Now Anderson and colleagues have come up with a new family of light-sensitive drugs that are designed for efficient two-photon excitation. They demonstrate selective closure of blood vessels in mice using one of their new drugs.
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.
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.
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.
Light Up The World, a non-profit organization founded by optical engineer Dave Irvine-Halliday, is on a mission to bring safe, clean and affordable lighting to impoverished people. Nature Photonics finds out more.
