Optical delay line for high time resolution measurement: W-type delay line.

We propose and demonstrate a newly designed optical delay line (W-type delay line) that improves the resolution of optical path length, namely, time resolution, by an order of more than 3 in comparison to the spatial resolution of a conventionally used translational stage. Using a conventional mechanical translational stage having a spatial resolution of 1 mum, the performance of the W-type delay line was evaluated by interferometric measurements with a diode laser, and the time resolution of 16 as was confirmed.

Time-resolved sum-frequency generation spectroscopy of methoxy and deuterated methoxy on Ni(111) using near-infrared laser pulses.

Methoxy (CH3O-) and deuterated (d-) methoxy (CD3O-) species on Ni(111) are investigated by sum-frequency generation (SFG) spectroscopy. Methoxy adsorbed on the Ni(111) surface is confirmed by SFG spectroscopy to be oriented normal to the surface. Two resonant peaks produced by methoxy, at 2921 and 2821 cm(-1), are assigned to Fermi resonance between the CH symmetric stretching and overtone modes.

Pulse shaping effect on two-photon excitation efficiency of alpha-perylene crystals and perylene in chloroform solution.

We demonstrated that the two-photon excitation efficiency of perylene in chloroform solution as well as that of crystalline perylene was dramatically increased by optimizing the shape of intense femtosecond laser pulses of a regenerative amplifier output. The efficiency was three times higher than for an unshaped single femtosecond pulse with the pulse width of shorter than 50 fs. The pulse shape optimized for the solution sample was a pulse train with a repetition frequency of about 340 cm(-1), and the pulse shape optimized for crystalline perylene was very similar.

Optical control of two-photon excitation efficiency of alpha-perylene crystal by pulse shaping.

Optimized pulse shaping experiments were carried out on the control of two-photon excitation efficiency of an alpha-perylene crystal in the temperature region from 30 to 290 K. It was found that a pulse train with a pulse interval of 90 fs and an alternately reversing phase relation increased the excitation efficiency by a factor of 2 for the whole temperature region. The pulse shape characteristic for effective efficiency increase was reduced by double pulse experiments in which the dependence of the emission intensity on the pulse interval and relative phase between pulses were measured.