• In our laboratory, miniature and highly-functional photonic devices based on new optical phenomena caused by the interaction of ultrafine microstructures with light have been studied. In addition, development of new production technology to overcome the problems that have been obvious from the practical application viewpoint of nanophotonic devices has been performed.
• • -Main research topics--
  MEMS tunable metamaterials for optical control.
• Structural color filters using subwavelength gratings for the applications of display and spectroscopic analyzers.
• Surface-smoothing technology using surface self-diffusion.
• Study of low loss silicon nanophotonic devices.

We aim to realize optical filters, optical resonators, and color filters, by using above technologies. Also, development of nano-photonic elements fabricated by a nanoimprint technology has been progressed.
We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• Nanoporous metals have drawn considerable attention due to their highly functional properties. They are generally produced by selective dissolution of elements from a multicomponent alloy (known as the dealloying method). As this method is based on differences in the electrode potential of each element present in the alloy, and this potential is high for noble metals, porous structure can be obtained only for noble metals. Recently we have found a new, simple and easy dealloying method without using aqueous solution, which enable us to develop an open nanoporous non-oxidized metallic material even with base metals (such as Ti, Ni, Cr, Fe, Mo, etc), metalloids and their alloys.

This technique is very powerful for developing new functional electrodes, catalysts, filters as well for removing toxic metallic element from the surface of biomaterials containing the toxic element.

• Our research aims at developing methods, including instrumentation, for characterizing surface (or interface) at the nano-meter level. Most of our research subjects are related to the surface forces measurement, which can directly monitor the interaction between two surfaces. We study phenomena occurring at the solid-liquid interface such as adsorption and structuring of liquids. We have developed the resonance shear measurement which is a sensitive method for evaluating properties of confined liquid for nano-rheology and tribology. Twin-path surface forces apparatus we developed enabled us to study wide variety of samples such as metals, ceramics and plastics.

These methods are applicable for characterizing lubricants, nano-materials, paints, sealants, and cosmetics. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• 1) We investigate interesting properties of nanostructures and develop materials and devices utilizing nanostructures.
• 2) We have techniques and skills on low-noise electric measurements, cryogenics, nanofabrication, and data informatics. We are open to new collaborations.

• The emergence of stress corrosion cracking is one of the most important issues from the viewpoint of aging management and maintenance of nuclear power plants. There is a large discrepancy between stress corrosion cracking and other cracks such as fatigue cracks from the viewpoint of nondestructive testing and evaluations, which requires suitable specimens containing stress corrosion cracking for the development of nondestructive testing and evaluation techniques and also for personnel training. However, artificially introducing stress corrosion cracking needs large cost and long time. Furthermore, several studies have pointed out that such articial stress corrosion cracking is not always similar to natural ones. On the basis of the background above, we develop a method to fabricate "imitative" stress corrosion cracking specimens using diffusion bonding.

The method enables one to introduce a region whose response is almost identical to actual stress corrosion cracking from the viewpoint of nondestructive testing. Whereas the dimension of the region is accurately controllable, the method requires much less cost and time comparing the conventional ones using corrosive environment. Patent is already applied for.

• The objectives of my researches are the development of high performance magnets and improvement of their magnetic properties. I have already developed following high performance magnets, such as Nd-Fe-B magnets using didymium, Sm-Fe-N high coercive powders prepared by HDDR and Fe-Cr-Co magnets. Recently, I have studied about the reduction of Dy content in Nd-Fe-B magnets for the use of HEV and have succeeded to develop high coercive Dy-free Nd-Fe-B sintered magnets by decreasing the grain size. I have also developed new kinds of microwave absorbers for the use in the frequencies of GHz range using permanent magnetic materials or nanoparticles.

High performance magnetic materials can be used in many applications in automobile, home electronics, IT and medical industries. We hope to conduct collaborative researches with companies producing magnetic materials for the use in these applications, which aims to improve magnetic properties or to develop new magnetic materials.

• The emergence of stress corrosion cracking is one of the most important issues from the viewpoint of aging management and maintenance of nuclear power plants. There is a large discrepancy between stress corrosion cracking and other cracks such as fatigue cracks from the viewpoint of nondestructive testing and evaluations, which requires suitable specimens containing stress corrosion cracking for the development of nondestructive testing and evaluation techniques and also for personnel training. However, artificially introducing stress corrosion cracking needs large cost and long time. Furthermore, several studies have pointed out that such articial stress corrosion cracking is not always similar to natural ones. On the basis of the background above, we develop a method to fabricate "imitative" stress corrosion cracking specimens using diffusion bonding.

The method enables one to introduce a region whose response is almost identical to actual stress corrosion cracking from the viewpoint of nondestructive testing. Whereas the dimension of the region is accurately controllable, the method requires much less cost and time comparing the conventional ones using corrosive environment. Patent is already applied for.

• We are developing a non-destructive testing method for the long range rapid inspection of metallic pipe using microwaves. The method propagates a microwave inside a pipe, and evaluates flaws appearing at the inner surface of the pipe on the basis of the reflection and transmission of the microwave. The method does not require scanning probes unlike conventional non-destructive methods, which enables one to inspect a pipe quite quickly. Our experimental validations have demonstrated the effectiveness of the method using a pipe as long as 30 m.

The NDT method proposed here is applicable when many pipes are inspected or conventional methods are not available due to pipe length and its configuration.