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D S Citrin

Publications and source records attributed to D S Citrin.

6 recordsLinked to original sources
PubMed2006

Plasmon-polariton transport in metal-nanoparticle chains embedded in a gain medium.

Plasmon-polariton transport on chains of noncontacting noble-metal nanoparticles suffers from severe attenuation. A possible way of countering the attenuation by embedding the nanoparticle chain in an optical-gain medium is considered. It is found that short-wavelength surface polaritons can acquire exponential growth that can counter nonradiative loss. This is most pronounced for modes polarized transverse to the chain axis immediately outside the light line; this growth factor is likely to be sufficient to counterbalance losses and so lead to low-attenuation propagation of plasmon polaritons in nanoparticle chains.

Journal Article↗
PubMed2005

Quantum coherence in an optical modulator.

Semiconductor quantum well electroabsorption modulators are widely used to modulate near-infrared (NIR) radiation at frequencies below 0.1 terahertz (THz). Here, the NIR absorption of undoped quantum wells was modulated by strong electric fields with frequencies between 1.5 and 3.9 THz. The THz field coupled two excited states (excitons) of the quantum wells, as manifested by a new THz frequency- and power-dependent NIR absorption line. Nonperturbative theory and experiment indicate that the THz field generated a coherent quantum superposition of an absorbing and a nonabsorbing exciton. This quantum coherence may yield new applications for quantum well modulators in optical communications.

Journal Article↗
PubMed2005

Plasmon polaritons in finite-length metal-nanoparticle chains: the role of chain length unravelled.

While the conceptual framework for nanoplasmonic waveguides composed of a chain of noncontacting metal nanoparticles usually neglects the effects of the ends, the long-range nature of the interparticle coupling underlying the electromagnetic transport means that finite chain length can play an important role. Here, the complex energies of the plasmon-polariton modes in finite-length nanoparticle chains are calculated to ascertain the effects of chain length on the mode dispersion and the radiative contribution to the attenuation. The results indicate that, for typical parameters, the infinite-chain limit is reached with approximately 10 nanoparticles. Thus, even for chain lengths well exceeding the attenuation length, long-range coupling of distant nanoparticles is shown to impact the dispersion and radiative loss.

Computer Simulation↗
PubMed2004

Magnetic Bloch oscillations in nanowire superlattice rings.

The recent growth of semiconductor nanowire superlattices encourages hope that Bloch-like oscillations in such structures formed into rings may soon be observed in the presence of a time-dependent magnetic flux threading the ring. These magnetic Bloch oscillations are a consequence of Faraday's law; the time-dependent flux produces an electromotive force around the ring, thus leading to the Bloch-like oscillations. In the spectroscopic domain, generalized Wannier-Stark states are found that are manifestations of the emf-induced localization of the states.

Journal Article↗
PubMed2004

Rabi flopping in a two-level system with a time-dependent energy renormalization: intersubband transitions in quantum wells.

We obtain pulse-driven Rabi oscillations guided by a generalization of the rotating-wave approximation to include, in the optical-Bloch equations, two-level systems with a time-varying transition energy. We achieve this by using chirped pulses with the central frequency given by the time-varying transition energy. Using this approach, we predict Rabi oscillations in intersubband transitions in a two-subband n-type modulation-doped quantum well by taking into account the time-dependent intersubband energy-gap renormalization due to depolarization-shift effects. We obtain Rabi oscillations for jpi (j=0,1,2, ) pulses in the presence of dephasing.

Journal Article↗