Fabrication of Vertical-Taper Structures for Silicon Photonic Devices by Local-Thickness-Thinning Process

We have developed a simple fabrication process of low-insertion-loss vertical-taper structures which can locally optimize the Si thickness of silicon-photonic devices. Fabricated vertical-taper structures realized the conversion of Si-waveguide thickness from 400 nm to 220 nm, whose insertion loss was measured to be less than 0.5 dB.