Focused ion beam milling of gallium phosphide nanostructures for photonic applications

Abstract

Abstract:We report on the fabrication of gallium phosphide (GaP) nanowaveguides of controlled dimensions, as small as 0.03 μm and aspect ratio in excess of 20, using focused ion beam (FIB) milling. A known limitation of this fabrication process for photonic applications is the formation of gallium droplets on the surface. We demonstrate a postfabrication step using a pulsed laser to locally oxidize the excess surface gallium on the FIB milled nanostructures. The process significantly reduces the waveguide losses. The surface optical quality of the fabricated GaP nanowaveguides has been evaluated by second-harmonic generation experiments. Surface and bulk contributions to second-order optical nonlinearities have been identified by polarization measurements. The presented method can potentially be applied to other III-V nanostructures to reduce optical losses.

Low-Temperature Bonding of Nanolayered InGaP/SiO2 Waveguides for Spontaneous-Parametric Down Conversion

“… This technique allows a material-independent bonding of nanolayered devices while preserving the position of the structures in the epitaxial grown wafer. The quality of the transferred III–V nanostructures has been evaluated by means of spontaneous parametric down-conversion (SPDC) processes. , Detailed dispersion studies have been performed to achieve modal phase matching, allowing equiphase velocity propagation of the signal and idler modes . Additionally, the coincidence rates of the counter-propagating photon pair with out-of-plane pump excitation have been measured.…”