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Proceedings Paper

1.32 μm InAs/InGaAs/GaAs quantum dot lasers operating at room temperature with low threshold current density
Author(s): Abdelmajid Salhi; Vittorianna Tasco; Luigi Martiradonna; Giuseppe Visimberga; Laura Fortunato; Milena De Giorgi; Massimo De Vittorio; Roberto Cingolani; Adriana Passaseo
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Paper Abstract

We report on the growth and characterization of low threshold 1.32-μm quantum dots (QDs) laser diodes. The quantum dot active region was optimised to get the highest photoluminescence emission and the lowest Full Width at Half Maximum (FWHM). From samples containing multilayer QDs and using the Limited-Area Photoluminescence (LAPL) technique we have shown that the gain of an N-layer structure is higher than N times that of a single layer. This enhancement is attributed to the increase of the quantum dot density in the upper layers and also to the use of the high growth temperature spacer layer. Broad area laser diodes were processed from the grown samples containing three layers of InAs QDs grown directly on GaAs and capped with 4-nm-thick InxGa1-xAs layer. Than measurements were performed at room temperature under pulsed excitation. The laser diodes operate at room temperature and emit between 1.29 and 1.32-μm which is beyond the strategic telecommunication wavelength. The characteristic temperature is around 80 K and very stable in the hole range of the operating temperature (from 0 to 90 °C). The internal quantum efficiency is 53% and the modal gain per QD layer was estimated to be ~ 6 cm-1. For an infinite cavity length a threshold current density of 8 A/cm2 per QD layer was obtained. From the calculation of the optical confinement of QDs, we have estimated a material gain of 1979 cm-1.

Paper Details

Date Published: 14 April 2006
PDF: 8 pages
Proc. SPIE 6184, Semiconductor Lasers and Laser Dynamics II, 618419 (14 April 2006); doi: 10.1117/12.662752
Show Author Affiliations
Abdelmajid Salhi, National Nanotechnology Lab., CNR-INFM (Italy)
Vittorianna Tasco, National Nanotechnology Lab., CNR-INFM (Italy)
Luigi Martiradonna, National Nanotechnology Lab., CNR-INFM (Italy)
Giuseppe Visimberga, National Nanotechnology Lab., CNR-INFM (Italy)
Laura Fortunato, National Nanotechnology Lab., CNR-INFM (Italy)
Milena De Giorgi, National Nanotechnology Lab., CNR-INFM (Italy)
Massimo De Vittorio, National Nanotechnology Lab., CNR-INFM (Italy)
Roberto Cingolani, National Nanotechnology Lab., CNR-INFM (Italy)
Adriana Passaseo, National Nanotechnology Lab., CNR-INFM (Italy)

Published in SPIE Proceedings Vol. 6184:
Semiconductor Lasers and Laser Dynamics II
Daan Lenstra; Markus Pessa; Ian H. White, Editor(s)

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