Intersubband gain and stimulated emission in long-wavelength(Λ=13 Μm) intersubband In(Ga)As-GaAs quantum-dotelectroluminescent devices

摘要

The dynamics of injected carriers and the conditions fornintersubband gain and population inversion in In(Ga)As-GaAsnself-organized quantum dots have been studied. Direct femtosecondnpump-probe spectroscopy as a function of temperature and excitationndensity confirms earlier results and shows a long (>100 ps) electronnrelaxation time between the excited states and ground state in the dots.nIntersubband gains as high as 170 cm-1 are calculated in thendots. Far-infrared spontaneous emission centered around 13 Μm isnobserved in edge-emitting light-emitting diodes. Stimulated emission,nwith a distinct threshold around 1.1 kA/cm2 in thenlight-current characteristics, is observed in plasmon-enhanced waveguidendevices. The intersubband threshold occurs after a threshold is observednfor interband lasing (~1 Μm) in the same device