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Home > Introduction of our tenure-track faculties > Miyaji Godai

Introduction of our tenure-track faculties

Miyaji Godai

Affiliation Institute of Engineering
Division Division of Advanced Applied Physics
Research field Nonlinear optics, quantum optics, laser engineering
Keyword(S) Femtosecond laser matterial processing, nanostructure fabrication, attosecond laser pulse generation
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Research experience

・Apr.2004-Feb.2014: Assistant professor, Institute of Advanced Energy, Kyoto University
・Feb.2014-Present: Associate professor, Tokyo University of Agriculture and Technology

Educational background

・1999: BE, School of Engineering Science, Osaka University
・2001: ME, Graduate school of Engineering Science, Osaka University
・2004: Ph. D. in Engineering, Graduate school of Engineering Science, Osaka University

Awards

・Mar.2013: IAE, Kyoto Univ. Research Award 2012
・May 2014: Laser Society of Japan Best Paper Award 2014

Selected papers and publications

・K. Miyazaki and G. Miyaji, "Nanograting formation through surface plasmon fields induced by femtosecond laser pulses", J. Appl. Phys., 2013, 114, 153108/1-6.
・G. Miyaji and K. Miyazaki, "Role of multiple shots of femtosecond laser pulses in periodic surface nanoablation", Appl. Phys. Lett., 2013, 103, 071910/1-4.
・G. Miyaji, K. Miyazaki, K. Zhang, T. Yoshifuji, and J. Fujita, "Mechanism of femtosecond-laser-induced periodic nanostructure formation on crystalline silicon surface immersed in water", Opt. Express, 2012, 20, 14848-14856.
・K. Yoshii, G. Miyaji, and K. Miyazaki, "Retrieving angular distributions of high-order harmonic generation from a single molecule", Phys. Rev. Lett., 2011, 106, 13904/1-4.
・K. Yoshii, G. Miyaji, and K. Miyazaki, "Dynamic Properties of Angle-Dependent High-Order Harmonic Generation from Coherently Rotating Molecules", Phys. Rev. Lett., 2008, 101, 183902/1-4.
・G. Miyaji and K. Miyazaki, "Origin of periodicity in nanostructuring on thin film surfaces ablated with femtosecond laser pulses", Opt. Express, 2008, 16, 16265-16271.
・F.H.M. Faisal, A. Abdurrouf, K. Miyazaki, and G. Miyaji, "Origin of anomalous spectra of dynamic alignments observed in N2 and O2", Phys. Rev. Lett., 2007, 98, 143001/1-4.
・G. Miyaji and K. Miyazaki, "Nanoscale ablation on patterned diamondlike carbon film with femtosecond laser pulses", Appl. Phys. Lett., 2007, 91, 123102/1-3.
・G. Miyaji and K. Miyazaki, "Ultrafast dynamics of periodic nanostructure formation on diamond-like carbon films irradiated with femtosecond laser pulses", Appl. Phys. Lett., 2006, 89, 191902/1-3.
・K. Miyazaki, M. Kaku, G. Miyaji, A. Abdurrouf, and F.H.M. Faisal, "Field-Free Alignment of Molecules Observed with High-Order Harmonic Generation", Phys. Rev. Lett., 2005, 95, 243903/1-4.

Research Description

I have studied the principle of photon science on nanophotonics, and have tried to apply it to innovative photon technology. Especially, my research interest has been focused on the development of new techniques for material nanoprocessing, material precise control, and measurement of ultrafast dynamics with spatially- and temporally-controlled photons. I briefly describe my research themes, as follows.

- Study of physical mechanism of femtosecond-laser-induced nanostructure formation on solid surfaces and application to laser nanoprocessing
The development of material nanoprocessing technique is much important for pioneering next-generation technology and growing sustainable industry. As one of its elemental technologies, laser material processing has been attracted and enthusiastically studied. While the spatial resolution of the conventional laser processing is restricted to the laser wavelength by diffraction limit of light, I have observed that intense femtosecond (fs) laser pulses can produce self-organized, periodic nanostructures on solid surfaces, where the structure size is typically 1/10 to 1/5 of the laser wavelength. Based on the ablation experiments, the observation of its ultrafast dynamics with a pump-probe technique, and the numerical simulation of electromagnetic field distribution, I have succeeded to demonstrate that near-field enhanced with fs laser pulses plays an essential role to initiate the nanoscale ablation on the target surface, and then the nanoscale periodicity can be attributed to the excitation of surface plasmon polaritons (SPPs) in the surface layer. Based on this picture of nanostructuring, we have successfully fabricated a uniform nanograting structure on GaN surface that consists of parallel stripes with a nano-period.

- Generation of vacuum ultraviolet attosecond laser pulses and application to observation technique for ultrafast dynamics of solid surfaces
A pump-probe method with pulse laser is widely used as a technique for the time-resolved measurements of ultrafast dynamics of materials. While the access to attosecond time region has been attracted in order to observe and control electrons in materials and ultimate behavior of atoms, we can get the attosecond coherent pulses only through the interaction process of the intense fs laser pulses with gas. The phenomena is so-called high-order harmonic generation. Since its detailed physical mechanism is still being discussed, I have studied the physical mechanism in detail. Now, I am studying the generation mechanism of single attosecond pulses and the interaction process of the pulses with solid materials.

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About TUAT's tenure-track program

The TUAT Tenure Track Program is excellent for quickly building-up of new laboratory, because it gives me the big financial support, and provides me abating instruction and other works in the university. This program also offers me much opportunity for communicating with many tenured teachers to hold much their experience and knowledge. As a result, I was able to build up my laboratory without hesitation. If this program such as the TUAT Tenure Track Program is expanded to all over the country, the education and research systems in the university are expected to be changed.

Future aspirations

Material science with ultrashort laser pulses is very interesting field, because there is much physical mechanism to be clarified and it can be applied to industrial technology. Through my research outcomes, I would like to play a key role of making a common foundation in various kinds of fields for science and technology.