A LIGHT TOUCH
PROFESSOR SUSUMU NODA – KYOTO, JAPAN

 

My work is currently focusing on 'photonic crystals', which are nanostructures for light with periodic refractive index change. They look like air-hole arrays in regular patterns.

By manipulating the patterns and developing two- or even three-dimensional structures, various and flexible manipulations of light become possible. Our research has demonstrated that photonic crystals allow light to be manipulated almost on demand.  This could contribute to broad applications including communication, information, storage, processing, and even global energy issues.

For example, we have successfully demonstrated that photonic crystals can produce photonic nano-devices with the sizes less than 1/100,000th of conventional on-road devices whilst achieving excellent optical functions. These devices can increase the amount of information in optical communications. We have also shown that photonic crystals enable a nanocavity (a cage of light), which can confine light very strongly. The nanocavity can be used for slowing, and even stopping, light. At the moment in optical signal processing, light signals are at first converted to electronic signals to store the signals, and then re-converted to light signals. If we could directly store light as it is, the speed of the signal processing could be significantly increased. The nanocavity is also important for quantum information processing and communication, which are considered as the important candidates for the next generation of communication and signal processing.

Moreover, we have demonstrated that photonic crystals can produce an unprecedented type of lazers, which cannot be achieved by the conventional technologies. We found that the photonic-crystal lazers can oscillate in a perfect single mode in a broad area and produce on-demand beam patterns with desired characteristics. These results will lead to the realization of various types of novel light sources; for example, (i) a light source with extremely high output powers, (ii) a super-resolution light source which can be focused much smaller than the wavelengths, and (iii) a light source which can trap and manipulate various materials such as small pieces of metals. [See movie which shows a comparison between a conventional lazer beam (Gussian beam) and a lazer beam (Doughnut beam) generated by a photonic-crystal lazer to trap and manipulate nontransparent materials (tungsten particles). In the case of conventional Gaussian beam, the tungsten particles cannot be trapped but are scattered.  On the other hand, in the case of the doughnut beam, the tungsten particles can be successfully trapped and manipulated.] These light sources achieved by the photonic-crystal lazers should be very important for lazer processing systems, next generation DVD systems, and versatile optical tweezers systems, etc.

Our work on photonic crystals will also contribute to address global energy issues. Photonic crystals can manage light emission and detection, which has great potentials to produce extremely highly-efficient LEDs and solar cells. These are important to save huge energies for lightings, and also to convert efficiently solar energy to electric one.  

I use ISI Web of Knowledge almost every day. I search the present state of related works, investigate more general recent research directions and also search for excellent young researchers to recruit. We sometimes use citation data to demonstrate our department's citation performance and this might be a very useful way to attract the young minds from across the world to our university.


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