Simulation of optical near field of a sub‐wavelength gold slit array and its electric quadrupole interaction with 1s excitons in Cu2O

Abstract

AbstractLaight propagation through a gold film with a periodically structured 50 nm width slit array into Cu2O has been calculated with a FDTD (Finite Difference Time Domain) method with a 5 nm mesh‐grid. Owing to the presence of a guided mode in the slit and a surface plasmon mode at the gold/Cu2O interface, optical near field generation in Cu2O are efficient in the case where the polarization of the incident light is perpendicular to the slit. The efficiency of the electric quadrupole (E2) transition of the 1s ‐exciton in Cu2O, which is modified by the field gradient of the excitation light, is evaluated for the calculated optical near field. Slit period dependences of the near field generation and the E2 transition efficiency are examined for a 50 nm thick array film. The enhancement of the effective E2 transition efficiency in the volume of 50 nm thickness above the film relative to the efficiency by the plane wave excitation is found to reach a factor 28 at the slit period of 110 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)