In the past few years, tremendous progress has been made on the utilization, fabrication and understanding of these devices that can focus energy from the far-field onto nanoscale regions and, conversely, enhance the radiation from subwavelength sources into the far-field. While the development of reliable and flexible nanofabrication techniques has been essential for this progress, it has also often been guided by extensive modeling based on computational electrodynamics.

The objective of this chapter is to describe the requirements for accurate electrodynamic modeling of optical antennas, to draw attention to specific pitfalls that can occur in that endeavor and to illustrate some recent modeling results. This chapter is organized as follows: after a brief introduction that describes the challenges associated with the electromagnetic modeling of optical antennas, we review in Sec. 10.2 some of the popular methods used for the electromagnetic simulation of plasmonic antennas, and emphasize in Sec. 10.3 the importance of assessing the convergence of a method and the accuracy of the results it produces. Section 10.4 illustrates the modeling of realistic optical antennas and the utilization of reciprocity to further check the accuracy of numerical results. Section 10.5 provides some typical results on the interaction between an optical antenna and its environment. The chapter concludes with some perspectives on what will be the next challenge in the electromagnetic simulation of plasmonic antennas.

From a computational electromagnetic point of view, the study of optical antennas requires the solving of Maxwell equations for the somewhat complex geometry of the antenna.