Research Interest

Interaction of ultrashort laser pulses with matter  theory and simulation We study the interaction of ultrashot laser and softxray pulses with atoms and molecules, where nonlinear optical effects and electronelectron interaction play an essential role. We also investigate novel methods to generate and measure ultrashort (attosecond) XUV and softxray pulses, mainly based on highorder harmonic generation (HHG, phenomenon in which laser light is converted to light with integer multiples of the laser frequency). The best way to study atomic and molecular dynamics under such circumstances theoretically is direct numerical solution of the timedependent Schr?dinger equation (TDSE). We apply this method to various kinds of atoms and molecules to study, for example, abovethreshold ionization (ionization process in which photoelectrons absorb further photons than the minimum necessary), highorder harmonic generation and twophoton double ionization. Our grand goal in emerging attoscience is to observe, control and manipulate electronic motion inside atoms and electrons at will. This will greatly contribute to technological innovation such as creation of unique atomic and molecular states, and the control of chemical reactions and intraatomic electron dynamics with the attosecond time scale. Recent and current research topics:
Computer design of subwavelength diffractive optical elements using the finitedifference timedomain (FDTD) method Diffractive optical elements (DOEs) are devices that can be used for precision laser beam control and shaping. With recent progress of nanotechnology, it is possible to fabricate DOEs with structures finer than optical wavelengths, namely, subwavelength structures (SWSs). We investigate the behavior of laser beams propagating in subwavelength DOEs using the FDTD simulation method and design novel devices with previously unattainable functions.Recent and current research topics:
