Title :
The role of high growth temperature GaAs spacer layers in 1.3-μm In(Ga)As quantum-dot lasers
Author :
Walker, C.L. ; Sandall, I.C. ; Smowton, P.M. ; Sellers, I.R. ; Mowbray, D.J. ; Liu, H.Y. ; Hopkinson, M.
Author_Institution :
Sch. of Phys. & Astron., Cardiff Univ., UK
Abstract :
We investigate the mechanisms by which high growth temperature spacer layers (HGTSLs) reduce the threshold current of 1.3-μm emitting multilayer quantum-dot lasers. Measured optical loss and gain spectra are used to characterize samples that are nominally identical except for the HGTSL. We find that the use of the HGTSL leads to the internal optical mode loss being reduced from 15 /spl plusmn/ 2 to 3.5 /spl plusmn/ 2 cm/sup -1/, better defined absorption features, and more absorption at the ground state resulting from reduced inhomogenous broadening and a greater dot density. These characteristics, together with a reduced defect density, lead to greater modal gain at a given current density.
Keywords :
III-V semiconductors; gallium arsenide; ground states; indium compounds; optical losses; optical multilayers; quantum dot lasers; semiconductor growth; spectral line broadening; thermo-optical effects; 1.3 mum; GaAs spacer layers; InGaAs; InGaAs lasers; absorption features; current density; defect density; dot density; emitting multilayer lasers; gain spectra; ground state; high growth temperature spacer; inhomogenous broadening; modal gain; mode loss; optical loss; quantum-dot lasers; Absorption; Gain measurement; Gallium arsenide; Loss measurement; Nonhomogeneous media; Optical losses; Quantum dot lasers; Stimulated emission; Temperature; Threshold current; Optical gain; optical loss; quantum dots (QDs); semiconductor lasers;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2005.854393
