Introduction of our laboratory
Ultrafast and Nonlinear Optical Processes, Quantum Optics, Quantum Photobiology
In order to evaluate ultrafast nonlinear optical susceptibilities of
optoelectronic device materials, we develop new methods for time-resolved
nonlinear spectroscopy and measure time dependence of optical
nonlinearities. On the basis of these measurements we clarify mechanisms of
nonlinearities, and give guiding principles for designing new optoelectronic
- Development of ultrashort pulse lasers
- Generation of shortest 4.7fs visible pulses by noncollinear optical parametric amplifier (NOPA):
World shortest pulses in the
visible was obtained by two sets of carefully designed chirped mirrors
and a prism pair.
- Sub-5-fs real-time spectroscopy
A high-frequency multi-mode wavepacket motion with the three
carbon-carbon stretching modes and chain-deformation modes was
observed. The highly vibronic non-equilibrium in the relaxed state
characterized by the mode frequency and amplitude modulations
is well explained by non-adiabatic coupling of the
stretching and bending modes in the butariene-like backbone. This
is the first real-time observation of coupling between normal modes.
- Dye molecules/polymer film:
Self-induced modulation of vibration in dye molecules
a polymer film was observed using sub-5-fs pulses.
The modulation of potential curves was obtained from the frequency and
amplitude modulations of the observed vibrational mode.
Sub-5-fs real-time spectroscopy revealed that coherent molecular
vibrations coupled to the Frenkel exciton system. The oscillation
in the induced absorption spectrum is interpreted as the modulated
transition dipole moment due to the oscillator strength transfer.
- Quasi-one-dimensional halogen-bridged mixed-valence metal complex:
Wave packet motions both in ground and
self-trapped exciton (STE) states are observed as oscillatory
modulations. The energy relaxation rate of the non-thermal STE is determined. The
onset of the wave packet motion is delayed after the
photo-excitation on the STE potential
surface. This delay time is attributed to the internal conversion
between free exciton and STE states.
- Development of new measurement system
- Multiplex method for nonlinear susceptibility spectrum measurement:
Continuous spectrum of nonlinear susceptibility can
be measured by single shot using this system. The spectrum of the
nonlinear susceptibility of polydiacetlenes was measured and the
energy of 21Aglevel were able to be determined by that
- System of time-resolved spectroscopy in mid infra red region:
Ultrashort pulse laser in mid IR was constructed by optical
parametric amplifier. The spectrum region was
5μm-8μm. The pulse width was determined as
400fs by pump-probe signal of Si.
- Scanning near-field optical microscope(SNOM): In order to observe
an optical nonlinearity of a single J-aggregate, a SNOM has been
constructed. Both fluorescent and absorption spectra are
successfully observed with a special resolution more than 100nm.
- Quantum optics and teleportation
- Quantum teleportation:
The goal of our research is to achieve more than 0.58 fidelity which
is the current limit of accuracy in quauntum teleportation.
A 430nm high intensity light source is being constructed for
application in an optical
parametric ocsillator which generates squeezed entangled states
of the light field.
- Quantum photobiology
Femtosecond dynamics of bacteriorhodopsin was investigated by sub-5-fs
bond alternation was clearly observed with 5-fs time