Characterization of insertion loss and back reflection in passive hybrid silicon tapers

The optical properties of two hybrid silicon taper designs are investigated. These tapers convert the optical mode from a silicon waveguide to a hybrid silicon III/V waveguide. A passive chip was fabricated with an epitaxial layer similar to those used in hybrid silicon lasers. To separate optical scattering and mode mismatch from quantum-well absorption, the active layer in this paper was designed to be at 1410 nm, to allow measurements at 1550 nm. Using cutback structures, the taper loss and the taper reflection are quantified. Taper losses between 0.2 and 0.6 dB per taper and reflections below -41 dB are measured.