科研之友
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摘要
The gain and related characteristics of quantum dash structures are modeled and analyzed using a parabolic effective-mass theory and the density-matrix theory. Size fluctuation is included in the model and its effects are analyzed. Comparison of performance in terms of these characteristics has been made with quantum well (QW) and quantum wire structures. Owing to size fluctuation, quantum dashes have broad gain spectra, which allow wavelength tuning without significant increase in the injected carrier density. Quantum dashes have smaller differential gain than quantum wells, while the linewidth enhancement factors are similar for these two structures. Due to their broad gain profiles, quantum dashes have much smaller large-signal chirp (change of refractive index). These characteristics can be further improved by blueshifting the emission energy without significant change in the injected carrier density. After detuning, the differential gain can be improved only to half of quantum well's values and the large-signal chirp can be reduced to one-tenth of the QW's value.
