Second harmonic generation in germanium quantum wells for nonlinear silicon photonics
Abstract
Second-harmonic generation (SHG) is a direct measure of the strength of second-order nonlinear optical effects, which also include frequency mixing and parametric oscillations. Natural and artificial materials with broken center-of-inversion symmetry in their unit cell display high SHG efficiency, however the silicon-foundry compatible group-IV semiconductors (Si, Ge) are centrosymmetric, thereby preventing full integration of second-order nonlinearity in silicon photonics platforms. Here we demonstrate strong SHG in Ge-rich quantum wells grown on Si wafers. The symmetry breaking is artificially realized with a pair of asymmetric coupled quantum wells (ACQW), in which three of the quantum-confined states are equidistant in energy, resulting in a double resonance for SHG. Laser spectroscopy experiments demonstrate a giant second-order nonlinearity at mid-infrared pump wavelengths between 9 and 12 microns. Leveraging on the strong intersubband dipoles, the nonlinear susceptibility almost reaches 10^5 pm/V
Cite
@article{arxiv.2103.12620,
title = {Second harmonic generation in germanium quantum wells for nonlinear silicon photonics},
author = {Jacopo Frigerio and Chiara Ciano and Joel Kuttruff and Andrea Mancini and Andrea Ballabio and Daniel Chrastina and Virginia Falcone and Monica De Seta and Leonetta Baldassarre and Jonas Allerbeck and Daniele Brida and Lunjie Zeng and Eva Olsson and Michele Virgilio and Michele Ortolani},
journal= {arXiv preprint arXiv:2103.12620},
year = {2021}
}
Comments
30 pages, 6 figures, double line spacing