The small-signal response of 1.5 μm multiple-quantum-well lasers in a two-band-model approximation

The variation of the small-signal response of 1.5 μm unstrained multiple quantum-well lasers with the number of wells (N_W ) is studied theoretically in a two-band-model (TB) approximation. The quasi-Fermi energies, together with gain and spontaneous emission rate spectra, are formulated analytically assuming a finite-well model and flatband conditions, including the contributions from carriers in both the wells and the barriers. The gain spectrum shows two major peaks located at the lowest heavy-hole and light-hole transitions. Therefore, the lasers under investigation are treated as three-level systems. The optical confinement factors are evaluated numerically by the matrix transfer method. The traditional rate equations are reformulated and solved for the frequency and damping rate of the relaxation oscillations in terms of an equivalent circuit