Antireflection coating for quantum-well Bragg structures

Abstract

We develop a strategy to reduce large reflection losses from quantum-well Bragg structures through an antireflection coating technique. It is based on generalized refractive indices, which we call "effective coupling indices" (ECIs), that can be introduced to describe the coupling of light into quantum-well Bragg structures. For the example of a spectrally narrow band, which is relevant for slow-light applications, we clarify the dependence of the ECIs on the spectral bandwidth and discuss the relation between the ECIs and the group-velocity index. Numerical simulations of reflection spectra demonstrate the effectiveness of the ECI concept.