Optical Properties of the Substrate-Buried Spherical Dipole Nanoantenna

We studied the properties of a plasmonic nanoantenna in the form of a subwavelength metal sphere partly buried in a metal substrate with a hollow gap between the sphere and the substrate. Using a nickel sphere in a nickel substrate as an example, it is shown that imbedding a metal sphere deep into the substrate leads to the broadening and a strong red shift of its dipole resonance. Significant enhancement of the near electromagnetic field of the sphere in the gap region is demonstrated. The effect of all geometric parameters of the nanoantenna under study on its optical performance is studied. Enhanced transmission of a metal film with defects in the form of spherical particles embedded in it is demonstrated, which results from the leaking of the near electromagnetic field from the gaps to the opposite side of the film. The obtained results can find application in nanooptics for designing plasmonic nanoantennas for concentration, enhancement and redistribution of the electromagnetic field.