Open AccessTheory for n-type doped, tensile-strained Ge–Si_xGe_ySn_1−x−y quantum-well lasers at telecom wavelength
Author(s) -
GuoEn Chang,
ShuWei Chang,
Shun Lien Chuang
Publication year - 2009
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.011246
Subject(s) - materials science , doping , optoelectronics , laser , population inversion , quantum well , quantum dot , germanium , optics , band gap , semiconductor laser theory , semiconductor , silicon , physics
We propose and develop a theoretical gain model for an n-doped, tensile-strained Ge-Si(x)Ge(y)Sn(1-x-y) quantum-well laser. Tensile strain and n doping in Ge active layers can help achieve population inversion in the direct conduction band and provide optical gain. We show our theoretical model for the bandgap structure, the polarization-dependent optical gain spectrum, and the free-carrier absorption of the n-type doped, tensile-strained Ge quantum-well laser. Despite the free-carrier absorption due to the n-type doping, a significant net gain can be obtained from the direct transition. We also present our waveguide design and calculate the optical confinement factors to estimate the modal gain and predict the threshold carrier density.