56 research outputs found
Biexcitonic Bound and Continuum States of Homogeneously and Inhomogeneously Broadened Exciton Resonances
STRONG NONLINEAR OPTICAL RESONANCES IN CdSe WITH PICOSECOND RESPONSE TIME
Nous avons réalisé une diffusion lumineuse cohérente dans CdSe en basse température. Nous avons découvert des résonances optiques fortement nonlinéaire et d'origine excitonique. Le temps de réponse nonlinéaire et cohérente, le temps de déphasage, est de l'ordre de picoseconde.We have performed coherent light scattering in CdSe at low temperatures and found very strong nonlinear optical resonances of excitonic origin. The coherent nonlinear response time, or dephasing time, is in the picosecond range
Measuring Excitonic Coherence in Nanostructures: Time-Resolved Speckle Analysis versus Four-Wave Mixing
RECOMBINATION OF PHOTOGENERATED CARRIERS IN DOPED HYDROGENATED AMORPHOUS SILICON
Bulk recombination of photogenerated carriers is studied by transient photocurrent measurements in phosphorus doped a-Si:H. With light doping, the monomolecular recombination lifetime exceeds 10 ms and only a slow bimolecular recombination from extended states is observed. For very high initial carrier densities, a fast decay is suggested to be direct recombination from shallow band tail states
Coherent Exciton and Biexciton Nonlinearities in Semiconductor Nanostructures: Effects of Disorder
TIME RESOLVED RAMAN SPECTROSCOPY OF OPTICALLY GENERATED PHONONS IN III-V SEMICONDUCTORS
Grâce à un laser sub-picoseconde et à un système de diffusion Raman muni d'1 détecteur multicanaux ultra-sensible, nous avons obtenu des spectres de diffusion Raman résolus en temps à l'échelle de la sub-picoseconde et mesuré ainsi la dynamique des phonons LO hors d'équilibre dans GaAs et InAs. La dépendance en temps de la population de phonons en excès les variations du spectre avec le temps et le niveau d'excitation ont été étudiés.A sub-picosecond laser and a highly sensitive multichannel detector Raman scattering system have been combined to perform sub-picosecond, time resolved Raman scattering experiments on the dynamics of non-equilibrium LO phonons in GaAs and InAs. The time dependence of the excess phonon population and the changes in the spectral content with both time and excitation level have been studied
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