Design Bragg Reflectors Consisting of Quarter-Wave Stack and Impedance Matching Concept


The control of the group delay and group delay dispersion in the design ofchirped mirror is difficult. To reduce this difficult it is important to adopt what isso called impedance matching design. This paper presents a design of quart wavemirror which includes the impedance matching. The design is divided into twostages. In the first stage a quarter waves stack to provide high reflectivity ofover a bandwidth of the design and within certain limits is considered.The control on average group delay depends upon wavelengths that are function ofpenetration depth. However, the group delay as a function of wavelength showsperiodic variations due to the impedance mismatch between the ambient mediumand the mirror surface and its layers. In the second stage of the design taperedBragg stack over a wavelength range (600-1100nm) is adopted as a single chirp.