We are extensively exploring new optics and photon technologies exploiting various types of microscopes (especially three-dimensional microscopes), high power lasers, ultra-short-pulsed lasers, nano-fabrication technology, self-assembly phenomenon, living-cell manipulation, numerical analysis, and so on.
Recently we focus on artificial optical functional metallic nano structures, which is termed "metamaterials", and three-dimensional multilayer terabyte optical storages.
Ultimate goal of optical technology is enabling manipulation of light (photon) propagation with our complete control. From a simple hand glass to a leading microscope and semiconductor fabrication devices, controlling behaviors of light is achieved solely by laying out appropriate refractive index distribution in a three-dimensional space with lenses, prisms, mirrors, and so on. Namely, a degree of freedom in manipulating light depends on varieties of distribution in refractive index (in other words, materials) and their arrangement in a space. Refractive index of material is defined as square root of its relative permittivity ε and relative magnetic permeability μ. According to traditional understanding in opticas, the value of μ is fixed to unity, and only the value of ε can be arranged by changing a choice of material. Thus, the lack of controllability of the value μ pretty much narrows range of freedom in designing refractive index of a material, inhibit us from freely controlling behaviors of light.
A material which can bring a breakthrough the present situation is a metamaterial, which is an artificial material consisting of arrays of noble metal nano structures. Those metallic nano structures are equivalent of atoms and/or molecules making up a material. Thus, ε and μ of a material can be tuned by arranging design and/or material of unit nanometer-scale structure regardless of material's conventionally-defined ε and μ. This new approach overturns the long-held understanding that a material and it's optical properties automatically correspondent each other, and opens new possibilities of science and technology in optics and optical materials.
In a text book of optics, many theoretical limits such as resolution limit are shown. However, those mathematical consequences were derived with respect to the prerequisite that the value of μ of natural substances equals to 1. If a world where the value of μ is other than unity would come true, limitations today would not be limitations any more. Actually, metamaterial-based optical devices have already proved to exibit extraordinary optical phenomena. Our group is challenging to realize the dream -ultimate control of light- using our metamaerial technologies.