AUTHOR=Haines Jack , Gandolfi Marco , Franz Yohann , De Angelis Costantino , Guasoni Massimiliano 

TITLE=Mid-Infrared Frequency Generation via Intermodal Difference Frequency Generation in AlGaAs-On-Insulator Waveguides

JOURNAL=Frontiers in Photonics

VOLUME=2

YEAR=2021

URL=https://www.frontiersin.org/journals/photonics/articles/10.3389/fphot.2021.788174

DOI=10.3389/fphot.2021.788174

ISSN=2673-6853

ABSTRACT=<p>We investigate theoretically mid-infrared (MIR) generation via difference frequency generation in multimode AlGaAs-on insulator (AlGaAs-OI) waveguides. The large refractive index difference between the AlGaAs core and the silica cladding shrinks the modes size down to the sub-<italic>μm</italic><sup>2</sup> scale, and, together with AlGaAs strong second-order nonlinear polarization, empowers strong nonlinear effects. As a result, efficient MIR generation is obtained in few-cm long waveguides with sub-<italic>μm</italic><sup>2</sup> transverse section, where higher order modes are exploited to achieve the phase-matching condition. These observations suggest that multimode AlGaAs-OI waveguides could represent a novel promising platform for on-chip, compact MIR sources.</p>