Influence Of Quantum Well Barrier Height On The Amplitude-phase Coupling And The Spectral Linewidth In Quantum Well Lasers

Abstract

Recently, it has been found both theoretically and experimentally that the differential gain in quantum well lasers is significantly affected by the unavoidable thermal population of injected carriers in the upper subbands of the quantum well structure, especially in the states of the separate confinement heterostructure region (state filling effect). The differential gain depends on the rate of increase of the quasi Fermi energies with increasing injected carrier density. The presence of upper subbands with large density of states tends to clamp the Fermi energies thus leading to a low differential gain. The state filling effect also significantly affects the amplitude-phase coupling and the spectral linewidth in quantum well lasers as a direct consequence of its influence on the differential gain.