Dielectric film optical amplifier

An optical amplifier is described using an active dielectric film. Electromagnetic scattering from this type of active film has been studied in the past using infinite plane waves. The use of unbounded fields resulted in scattering coefficients that approached infinity at resonance. In this paper, the active scatterer is viewed as an optical amplifier with finite incident and scattered fields. An analytical description is presented and then supported by a numerical analysis. Finite gains are calculated. This analysis also predicts spatial filtering of the incident field, and experimental results confirm these predictions.