Kyung Sik Kang

Carrier-envelope-phase-dependent above-threshold ionization of xenon observed with multi-cycle laser pulses

Carrier-envelope-phase (CEP)-dependent modulation was measured in above-threshold ionization of xenon driven with 30-fs laser pulses. We showed the dependence from the asymmetry map obtained using a velocity map imaging spectrometer, up to 17 eV in photoelectron energy. The dependence appeared to be linear with a slope of one photon energy increase per CEP change of 2π and did not rely on the sign or the amount of laser chirp. Our results indicated the existence of the quantum interference between different multiphoton ionization paths.

Complete Temporal Reconstruction of Attosecond Harmonic Pulses

Using the FROG CRAB method, complete temporal reconstruction of attosecond harmonic pulses was achieved. The compensation of intrinsic attosecond chirp was also demonstrated in the harmonic generation medium itself, thereby achieving transform-limited attosecond pulses.

Compression of Attosecond Harmonic Pulses in the Harmonic Generation Medium Itself

The intrinsic chirp of attosecond harmonic pulse obtained from Ar was compensated by taking into account the material dispersion of the harmonic generation medium itself. The measured attosecond pulse duration was very close to the transform-limited value.

Complete Temporal Characterization of Attosecond High Harmonic Pulses using the FROG Technique

For complete temporal characterization of an attosecond harmonic pulse train the frequency-resolved optical gating technique is applied to the photoelectron spectra of He driven by high harmonic pulses and IR laser pulses with time delay, which shows the detailed temporal information of attosecond pulses in the attosecond pulse train.

Analysis of the vibrational structures from the autoionization in O2 using harmonics

Excitation to an autoionization level in O2 is achieved using a high harmonic light source. The 11th harmonic at 72.7 nm from Kr gas excites O2 in the ground state to the autoionizing level, and the dynamic behavior is investigated by laser-field-assisted photoionization with a pump-probe scheme.

Excitation and exploration of autoionization state in O 2 using XUV-harmonic pump and IR-laser probe

XUV harmonics are used to study the photoelectron spectrum of O₂. The autoionization states of O₂ are further investigated using XUV harmonic as pump and IR laser as probe.