Phonon resonances in the optical nonlinearity induced by the mixing of pump and probe pulses are investigated in an ?-sexithienyl vacuum evaporated thin film. We have performed femtosecond differential transmission spectroscopy at room temperature and at 20 K using excitation energies from 2.14 to 2.4 eV. We observe simultaneously an induced transmission at the Stokes and at the anti-Stokes energetic position of the pump pulse which is only present during the temporal overlap of the pump and the probe pulse. The phonon associated with the C=C stretching mode of ?-sexithienyl is involved in the coherent light-matter interaction for both the stimulated inverse Raman scattering at the anti-Stokes energetic position and for the Raman gain at the Stokes energetic position.
Observation of Phonon Resonances in the Optical Nonlinearity in Sexithienyl Thin Film
M Murgia;R Zamboni;
2000-01-01
Abstract
Phonon resonances in the optical nonlinearity induced by the mixing of pump and probe pulses are investigated in an ?-sexithienyl vacuum evaporated thin film. We have performed femtosecond differential transmission spectroscopy at room temperature and at 20 K using excitation energies from 2.14 to 2.4 eV. We observe simultaneously an induced transmission at the Stokes and at the anti-Stokes energetic position of the pump pulse which is only present during the temporal overlap of the pump and the probe pulse. The phonon associated with the C=C stretching mode of ?-sexithienyl is involved in the coherent light-matter interaction for both the stimulated inverse Raman scattering at the anti-Stokes energetic position and for the Raman gain at the Stokes energetic position.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
