Role of carrier reservoirs on the slow phase recovery of quantum dot semiconductor optical amplifiers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 94, 041112 (2009) and may be found at https://doi.org/10.1063/1.3073715.The gain and phase recovery dynamics of quantum-dot (QD) semiconductor optical amplifiers are calculated, including all the optical transitions involved in successive carrier recovery processes. The carrier recovery dynamics of inhomogeneously broadened QDs is simulated by solving 1088 coupled rate equations. The respective contributions of QD states and quantum-well carrier reservoirs to the gain and phase changes are identified both temporally and spectrally. We show that the slow phase recovery component of the QD ground state is induced by the slow carrier dynamics of the carrier reservoir due to a slowly varying line shape function of the refractive index change.EC/FP6/027638/EU/Transparent Ring Interconnection Using Multiwavelngth PHotonic switches/TRIUMPHDFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

Comparison of dynamic properties of ground- and excited-state emission in p-doped InAs/GaAs quantum-dot lasers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 104, 181101 (2014) and may be found at https://doi.org/10.1063/1.4875238.The dynamic properties of ground- and excited-state emission in InAs/GaAs quantum-dot lasers operating close to 1.31 μm are studied systematically. Under low bias conditions, such devices emit on the ground state, and switch to emission from the excited state under large drive currents. Modification of one facet reflectivity by deposition of a dichroic mirror yields emission at one of the two quantum-dot states under all bias conditions and enables to properly compare the dynamic properties of lasing from the two different initial states. The larger differential gain of the excited state, which follows from its larger degeneracy, as well as its somewhat smaller nonlinear gain compression results in largely improved modulation capabilities. We demonstrate maximum small-signal bandwidths of 10.51 GHz and 16.25 GHz for the ground and excited state, respectively, and correspondingly, large-signal digital modulation capabilities of 15 Gb/s and 22.5 Gb/s. For the excited state, the maximum error-free bit rate is 25 Gb/s.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement