Distance-dependence of the coupling between split-ring resonators and single-quantum-well gain

Abstract

We present low-temperature femtosecond pump-probe experiments on arrays of silver split-ring resonators coupled to single quantum wells, in which we vary the geometrical separation between the two components to study the variation of coupling with distance. Its strength is found to decrease exponentially with increasing separation with a 1/e length on the order of 8 nm. We further link our experimental results to numerical calculations of the near fields which show the same distance-dependence as the coupling strength in the experiment. Together, this confirms the assumption of a near-field-assisted coupling mechanism.