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An analytical expression of transient four-wave mixing (TFWM) in inverted semiconductor with carrier-injection pumping was derived from both the density matrix equation and the complex stochastic stationary statistical method of incoherent light. Numerical analysis showed that the TFWM decayed decay is towards the limit of extreme homogeneous and inhomogeneous broadenings in atoms and the decaying time is inversely proportional to half the power of the net carrier densities for a low carrier-density injection and other high carrier-density injection, while it obeys an usual exponential decay with other decaying time that is inversely proportional to half the power of the net carrier density or it obeys an unusual exponential decay with the decaying time that is inversely proportional to a third power of the net carrier density for a moderate carrier-density injection. The results can be applied to studying ultrafast carrier dephasing in the inverted semiconductors such as semiconductor laser amplifier and semiconductor optical amplifier. [ABSTRACT FROM AUTHOR]

Abstract: The temporal responses and the reflected digital signal behaviors of a novel InAs/GaAs one-dimensional quantum dot resonant photonic crystal (QD-RPC) with 400 periods of unit cell, consisting of an InAs quantum dot (QD) layer and other GaAs barrier layer, are theoretically investigated by using a transfer matrix method. We demonstrate that the stopband (resonant photonic band gap) has fast response and the Nyquist rate is up to 1.15THz centered at Bragg reflection wavelength 1242.3nm. The square-wave time series with the duration of 10ps reflected by the stopband is transmitted and the intensity of pump light utilized is only 0.32MW/cm2 when this structure acts as an all-optical switch for a given temperature 45K and relative size fluctuation 0.1%. In addition, the extinction ratios of this optical switch associated with temperatures and signal pulse durations are analyzed and discussed. [Copyright &y& Elsevier]

Abstract: In this paper, an efficient l 1-regularized reconstruction method named the primal-dual interior-point (PDIP) method is presented for three-dimensional bioluminescence tomography (BLT) based on the adaptive finite element framework. Taking into account the sparse characteristic of the bioluminescent source, the BLT inverse problem is considered to be a linear programming problem and is represented by its primal and dual form. The source localization and quantification are obtained by solving the primal-dual Newton equation system. The comparisons between PDIP and the classical conjugate gradient least square (CGLS) algorithm are implemented to validate our method. Results from numerical simulation and an in vivo mouse experiment demonstrate the credibility and the potential of the proposed method in practical BLT reconstruction. [Copyright &y& Elsevier]