Optical near-field excitation at the semiconductor band edge: Field distributions, anisotropic transitions and quadrupole enhancement

The optical near-field response of a three dimensional subwavelength aperture-semiconductor system is analyzed within a finite difference time domain scheme for Maxwell's and excitonic material equations. The analysis includes the field modification due to the high refractive index environment and the excitonic response to a near-field distribution. The resonant optical response is illustrated for anisotropic dipole transitions in quantum wells and the enhancement of the quadrupole transition in materials with dipole forbidden interband transitions.