The Saiki Laboratory is doing research on near-field optics. Its common knowledge that lenses can be used to focus sunlight into a small point. In the case of laser light, the point is even smaller, but the limit on the points size is about one micron. It cant be made any smaller. This is due to the diffraction limit of light, which is a basic obstacle that cant be overcome as long as lenses are used. The resolution of optical microscopes, the capacity of optical disks, and the process size in optical lithography are all restricted by the diffraction limit of light. The field of research that handles technology to overcome this barrier is called near-field optics.
Q. Im currently considering the development of microscopes with extremely high spatial resolution, and how to apply them. The microscopes people normally use have a physical restriction called the diffraction limit. They cant be used to observe things smaller than one micron. But we want to construct microscopes that overcome this limit, to observe a new physical world.
When light shines on a nanoscale object, some of it is scattered, while some remains around the object. The light remaining around the object is called evanescent light. It doesnt reach our eyes, as it stays on the object like a skin. So we cant usually know of its existence. The extent of the evanescent light is about the same size as the object, so it isnt subject to the diffraction limit; instead, it functions as an extremely small spot of light - in other words, a nanoscale light source. This nano-light source can be used to scan an observed object by bringing a pencil-shaped optical fiber probe, with a nanoscale point, close to the object. This is a near-field optical microscope, which overcomes the diffraction limit in imaging and spectroscopy.
Q. What were aiming for now, in collaboration with people from other research groups, is to reach the extreme spatial limit of the nanoscale, and the extreme temporal limit of the femtosecond, and combine them to create the ultimate light source. Wed also like to find materials that are a good match with the ultimate light source, and skillfully combine light-source technology and materials science to develop a new science.
As a new subject for research, the Saiki Lab is looking at phase-change materials, which are used in optical disks. When these are irradiated with femtosecond pulses, their structure changes on a very short time-scale. So extreme structural changes with respect to time and space can be caused by combining phase-change materials with nanoscale light sources. If this research progresses, itll be possible to develop new devices for storage and imaging. Its also hoped that this research can be applied to optical switches and high-capacity optical disks.
Q. Im currently considering how to handle light in the ultimate way. As I kept saying before, were working with the nanoscale and the femtosecond, and light also has the characteristic of polarization. Wed like to create light sources where those things are controlled at the ultimate possible level, but just making them isnt enough; whats really interesting is how they could be used. Wed like to use them on materials; in other words, to control the structures and properties of materials. I think the science that would be achieved by combining light-source technology and materials science is the most interesting aspect of this research. And as an experimentalist, I find it fascinating that there are so many ways to test my skills. I really hope that people who are interested in this will join our group.
Негізгі бет Ғылым және технология Toward the ultimate light source using near-field optics, in pursuit of the limits of time and space
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