Abstract

Integrated nonlinear photonics has recently drawn increasing research interests as it provides a compact solution compared with the conventional fiber devices. Silicon-on-insulator (SOI) has emerged as a promising platform due to its high material nonlinearity and its compatibility with the CMOS industry. Various nonlinear applications have been demonstrated in silicon [1]. However, silicon suffers two-photon absorption (TPA) in the telecommunication wavelength band around 1.55 μm, which hampers its applications. AlGaAs is also believed to be a good nonlinear material due to its high material nonlinearity. Moreover, its bandgap can be tailored by adjusting the Al concentration during epitaxial growth to avoid TPA in the telecom wavelength range. Previously, nonlinear parametric processes like four-wave mixing (FWM) have been demonstrated in deep-etched AlGaAs waveguides [2]-[4]. However, the low vertical index contrast mandates a challenging deep etching process which limits more advanced designs [5]. In addition, to attain a high effective nonlinearity, high index contrast is highly desired as it enhances light confinement in waveguides. In this paper, we propose an AlGaAs-on-insulator (AlGaAsOI) platform, where a thin AlGaAs layer on top of an insulator layer resides on a semiconductor substrate. The high index contrast not only relieves the etching process but also enhances the effective nonlinearity of waveguide devices. A highly efficient FWM in an AlGaAsOI nano-waveguide is demonstrated experimentally.

© 2015 IEEE