Physics of photonic semiconductor devices

PHYS-434 Lecture 7

07.04.2022, 12:24

In this lecture, we introduce the notion of Bragg mirror, also called distributed Bragg reflector (DBR), which is a powerful alternative to metallic mirrors to reach peak reflectivities in excess of 99%. DBRs consist of several quarterwave bilayers stacked on top of one another and for which constructive interference occurs at a predefined wavelength leading to an increase in the reflectivity. The relevant physics does rely on the important notion of optical thickness.  Specific optical features about DBRs are first detailed before we provide a general reminder about the physics of Fabry-Perot cavities. We then introduce the notion of planar microcavities, which are the microscopic equivalent of conventional Fabry-Perot cavities. The notion of photon storage is recalled, which is especially important to foster light-matter interaction. The notion of weak coupling and b coupling regimes are briefly mentioned at the end of the lecture.