Laser Characteristics of 1.3-$\mu$m Quantum Dots Laser With High-Density Quantum Dots

Abstract

We have reported the effects of using an As 2 source and gradient composition-strain reducing laser (GC-SRL) to fabricate InAs quantum dot (QD) structures. The coalescence of the coherent QDs was reduced under the As 2 source. We have realized high density (8.0 × 10 10 cm −2 per sheet) measured by SEM and high uniformity (full-width at half-maximum: 23 meV measured by photoluminescence at room temperature) QDs using an As 2 source and the GC-SRL technique. Further, we have demonstrated ninestack QD lasers with high-density and high-uniformity QDs for the first time. We achieved a large modal gain of 54 cm −1 at a ground state emission of beyond 1.3-µm. A very low threshold current can be realized by a quantum effect for further equalization of QDs. We believe that the method of fabricating this QD laser with high density, high uniformity, and high modal gain will qualify as a novel technique.Index Terms-1.3-µm quantum dot (QD) laser, As 2 source, gradient composition-strain reducing laser (GC-SRL), high-density QD, high modal gain.

Effect of the number of stacking layers on the characteristics of quantum-dash lasers

“…However, the results show an increase in th J for 2 lyr N  which suggests that A V dominates. Moreover, increase in th J could be due to an increase in modal gain as a result of stacking of the dash layers which has been reported experimentally [1,5,16]. Nevertheless, our model considers a fixed modal gain ( This observation is relatively consistent with the results from literature that are based on Qdot model [18] since Qdashes may be thought of an elongated Qdots with quasi zero dimensional DOS.…”

“…relation for th J in a similar manner reported for Qdots [16] lyr N  and 3 these parameters probably balance each other thus attaining a relatively small value of threshold current density. [5] and (b) calculated lasing wavelength as a function of the stack number for the Qdash lasers reported in [5] and [15], respectively.…”

“…Increase in A V due to stacking of the dash layers may enhance internal absorptions, thus affecting the threshold current density. On the other hand, a lower  (due to increase in A V as a result of increase in lyr N ) probably assists in attaining the modal gain ( th g  ) relatively fast, thereby decreasing the threshold current density [6,16]. However, the results show an increase in th J for 2 lyr N  which suggests that A V dominates.…”

“…The Qdash laser considered for the analysis is obtained from [15] and is based on the InAs/InP material system. Four stacks of InAs Qdashes with an average height of 1.5 nm and width of 20 nm constitutes the active region with volume 16 Figure 1 illustrates the effect of the number of stacking layers ( lyr N ) on the threshold current density ( th J ) of Qdash lasers. The experimental data is obtained from [5,6] and is plotted in Fig.…”

Effect of stack number on the threshold current density and emission wavelength in quantum dash/dot lasers

“…On the other side, for larger number of stacked layers, the optical waveguide part of threshold carrier concentration decreases sharply. The injected carriers distributed effectively into the QDH/QD dominate, and J th thus increases linearly with the number of stacked layers [17]. As a result, between the two extreme cases, a theoretical calculation based on Asryan's [11] model shows that the minimum J th exists at intermediate number of stacks, i.e.…”