Quality factor control of Si-based two-dimensional photonic crystals with a Bragg mirror

摘要

We have investigated the coupling between two-dimensional photonic crystals and a distributed Bragg reflector by fabricating silicon-based photonic crystals on top of a one-dimensional Bragg mirror. The two-dimensional photonic crystals contain Ge/Si self-assembled islands as an internal source covering the 1.1-1.6 μm spectral range. We show that we can control the quality factor of Bloch modes by varying the thickness of the silicon layer on top of the Bragg mirror. Quality factors up to 2200 are obtained for optical radiative modes collected from the surface for a photonic crystal with a square lattice pattern. The variation of the quality factor as a function of the thickness of the upper layer is confirmed by three-dimensional finite-difference time domain calculations of the investigated structures.