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We have investigated theoretically the interband excitonic absorption spectra and the coupling behaviors of coupled symmetric triple Zn1-xCdxSe/ZnSe quantum wells with diluted Mn doping in the central well under external magnetic field. The results show that the magnetic field can effectively adjust the energy levels and the optical properties of the coupled multiple quantum wells (CMQWs). The coupling behaviors of the CMQWs are very sensitive to the central well depth. The effect of the magnetic-field-introduced parabolic-confined potential on the main features of the absorption spectra can be neglected at moderate magnetic-field densities. [ABSTRACT FROM AUTHOR]

The optical absorption spectra in a quantum well driven both by an intense terahertz (THz) and by an optical pulse are theoretically investigated within the theory of density matrix. We found that the optical absorption spectra and the splitting of the excitonic peaks splitting can be controlled by changing the THz field intensity and/or frequency. The Autler–Towns splitting is a result of the THz nonlinear dynamics of confined excitons, which is in agreement with the experiments. In addition, the dependence of the optical absorption on the quantum well width and the carrier density is also discussed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of spectral photoluminescence (PL), photoconductivity and Hall mobility in undoped, n and p-type modulation-doped quantum wells of Ga1- x In x N y As1- y /GaAs with varying nitrogen concentration. We show that the increasing nitrogen composition red shifts the energy gap and this red shift is accompanied with a reduction of the 2D electron mobility in the quantum wells. True temperature dependence of the band gap, free from errors associated with nitrogen induced exciton trapping effects, is observed because in the modulation doped QW samples PL emission is dominated by band-to-band recombination and the S-shape temperature dependence is eliminated. Excellent fit to semi-experimental Varshni equation is obtained and the temperature dependence of the band gap in the linear regime (d E/d T) is tabulated as a function of nitrogen concentration and the type of dopant. [ABSTRACT FROM AUTHOR]

Asymmetric double quantum wells (ADQWs) are optimized to exhibit maximum optical modulation sensitivity by varying the barrier width, barrier position, and well width. Anticrossing of the two lowest excitons in ADQWs significantly enhances the modulation sensitivity. Consideration of exciton mixing is crucial to obtain accurate estimates of the effects. For a given linewidth of the excitonic peaks, we find optimum structural parameters that exhibit maximum modulation sensitivity. Values of dα/dE of ∼ 6.51 × 104 kV-1 at 4.2 K and of ∼ 1.25 × 10³ kV-1 at 298 K are predicted in GaAs-based ADQWs. The result provides new design guidelines in fabricating high-sensitivity QW electroabsorption modulators. [ABSTRACT FROM AUTHOR]