Analysis of the Optical Coupling Between GaSb Diode Lasers and Passive Waveguides: A Step Toward Monolithic Integration on Si Platforms

Abstract

We simulate the optical coupling between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.3\ {\boldsymbol{\mu m}}$</tex-math></inline-formula> GaSb-based diode lasers (DLs) epitaxially grown on on-axis silicon (001) and passive waveguides in the butt-coupling geometry. 3D FDTD simulations reveal how the optical coupling is affected by the air gap between the laser cavity and the waveguide that arises from the laser etched-facet definition. We also model alternative approaches consisting in filling the gap with higher-refractive index materials transparent in the mid-infrared window. Finally, because of their fabrication flexibility, we propose to implement polymeric waveguides in order to achieve improved coupling performances.