Optical Double-Resonant Raman Scattering in Semiconductor Planar Microcavities

Abstract

Studied first in the domain of atomic physics [1] and, more recently, in the field of semiconductors [2], optical microcavities have demonstrated their ability to strongly modify the excitation and emission characteristics of atoms embedded in them leading, for instance, to increased luminescence and reduced thresholds for laser gain. It has been clearly settled that the confinment of the photon field, or equivalently its enhancement at the core of the cavity, affects both first-order processes in light-matter interaction: emission and absorption [3]. By the same token, higher-order processes in which one or more photons are absorbed and/or emitted should be equally affected. One of such processes is Raman scattering (i.e., inelastic scattering of light), where one photon is absorbed and another emitted, both differing in the energy, and eventualy wavevector, of an excitation left behind [4]. Indeed, enhancement of Raman scattering due to photon field modifications has been reported for several systems, even prior to the use of microcavities. Already in 1979 Connel et al. [5] described the posibility to use the interferences generated by a reflecting surface to amplify the Raman signal of a thin film grown above it. Along conceptually similar lines, inelastic scattering enhancements were observed later in micrometer-size droplets acting as spherical optical cavities, including the observation of up to fourtenth-order Stokes peaks (creation of phonons) and of reduced thresholds for stimulated Raman gain [6]. Also, field confinement effects at the Stokes wavelength have been reported for liquide benzene in a piezoelectrically controled microcavity [7].