Electron localization in CdS nanocrystals studied by time-resolved terahertz spectroscopy
Measurement and Monte-Carlo simulations of THz photoconductivity spectra of CdS nanocrystalline films revealed a strong coupling between adjacent nanocrystals. Investigation of ultrafast dynamics provides information about initial sub-picosecond carrier cooling and subsequent carrier recombination.
Far-infrared response of free charge carriers localized in semiconductor nanoparticles
A Monte Carlo method is employed to calculate the dynamical conductivity in the terahertz range of free charge carriers localized in semiconductor nanoparticles. The shape of the conductivity spectrum is essentially determined by the probability of carrier transition through interparticle boundaries and by the ratio of the nanoparticle size and carrier mean free path in the bulk. It is shown that the conductivity spectrum exhibits similar features as the classical extension of the Drude conductivity of electrons proposed by Smith [Phys. Rev. B 64, 155106 (2001)]. We find and discuss the link of this model to the results of our simulations which suggests an interpretation of the phenomenological parameters of the Drude-Smith model.
Coherent pulsed injection seeding of two gain-switched semiconductor lasers
High-power, narrow-spectrum, short pulses at a wavelength near 830 nm are needed for optical logic applications. The authors report the generation of two coherent trains of pulses by pulsed injection seeding of two gain-switched semiconductor lasers with one mode-locked master oscillator. The available power was doubled and both lasers emit in nearly identical spectral lines. Short pulses (30-50 ps) are generated at a repetition rate of 1.9 GHz. The spectrum is reduced to a single mode cluster and shows a 1.7 AA wide chirp suitable for pulse compression. The peak power is 0.1 W for each pulse train. The capability of this technique for coherent power combining is demonstrated.<<ETX>>