Spectral and dynamic properties of InAs-GaAs self-organizedquantum-dot lasers

摘要

The spectral and dynamic properties of InAs-GaAs MOCVD-grownnvertically stacked self-organized quantum-dot lasers are studiednexperimentally. A strong mode grouping effect (quasi-periodic modulationnof the lasing spectrum) is observed and interpreted as a result ofnwavelength-dependent losses in the laser waveguide associated withnsubstrate leakage and reflection. Some samples also display a broadernspectral modulation which may be attributed to lasing from differentngroups of dots, or energy levels. Experimental observations are innagreement with a theoretical explanation involving increased opticalnnonlinearities due to the localized nature of carriers. In relaxationnoscillation pulse trains, a substructure is observed which we believe tonbe a dynamic manifestation of the same carrier localization effects; anpreliminary rate-equation simulation supports this interpretation