Short Bragg mirrors with adiabatic modal conversion

Abstract

A silicon-on-insulator waveguide-based microcavity with short tapers has been realized by incorporating two identical eight-groove tapers at the two reflector extremities. The microstructure has an overall length of 14 μm and consists of two first-order Bragg mirrors with narrow slits (90 nm) and of four series of slits with progressively varying widths (tapers). A comparison with a nontapered cavity evidences the beneficial effect of the taper, a lowering of the radiation losses.