On spectral line broadening in quantum-well heterostructure lasers

摘要

Theoretical analysis of the emission line broadening in quantum-well lasers is carried out taking into account the Coulomb interaction of current carriers in the approach of two-dimensional electron-hole gas. The principal idea of the used method consists in the determination by means of the perturbation theory for many-body systems the functional behavior of tails of the emission line and in the subsequent extrapolation of the central part of the line according to a normalization requirement. Based on the obtained in the parabolic band approximation analytical shape function for the homogeneously broadened spectral line, the influence of various factors on the optical spectrum is analyzed. An explanation of the experimental data, including the spectral line asymmetry and the linewidth change versus temperature and power excitation, is given. Results of the numerical calculations are presented for quantum-well heterostructure laser diodes in the GaInAsSb-AlGaAsSb-GaSb system. Spectra of luminescence and gain in dependence on the quantum well width, temperature, and excitation level are examined. Spectrum transformation in the long-wavelength range and tuning curves for the GaSb-based laser emitters are also discussed. New possibility to overlap the spectral emission diapason of 2.2-2.9 μm is examined due to asymmetric multiple-quantum-well heterostructure configuration of the active region.