Optimization of Grating Coupler Efficiency for Nanophotonic Device Integration

A unique experimental apparatus has been developed for the optical characterization of nanophotonic devices. Grating couplers with nanoscale periodicity have been fabricated on silicon-on-insulator (SOI) substrates by electron beam lithography (EBL) and reactive ion etching (RIE). The coupling efficiency of these gratings has been measured as a function of grating depth and the angle and wavelength of incident radiation. A coupling efficiency of at least 5.2% is demonstrated for 1568 nm light incident at 40°.