Impedance matching and emission properties of optical antennas in a nanophotonic circuit

TL;DR

This paper investigates how impedance matching affects the emission and coupling efficiency of optical nano antennas in a nanophotonic circuit, using simulations to optimize antenna design for improved performance.

Contribution

It introduces a method to infer and optimize nano antenna impedance matching in nanophotonic circuits through simulation and geometric adjustments.

Findings

Impedance matching can be inferred from standing wave patterns.

Adjusting antenna length and width optimizes impedance matching.

Radiation efficiency depends on antenna geometry, not impedance matching.

Abstract

An experimentally realizable prototype nanophotonic circuit consisting of a receiving and an emitting nano antenna connected by a two-wire optical transmission line is studied using finite-difference time- and frequency-domain simulations. To optimize the coupling between nanophotonic circuit elements we apply impedance matching concepts in analogy to radio frequency technology. We show that the degree of impedance matching, and in particular the impedance of the transmitting nano antenna, can be inferred from the experimentally accessible standing wave pattern on the transmission line. We demonstrate the possibility of matching the nano antenna impedance to the transmission line characteristic impedance by variations of the antenna length and width realizable by modern microfabrication techniques. The radiation efficiency of the transmitting antenna also depends on its geometry but is independent of the degree of impedance matching. Our systems approach to nanophotonics provides the basis for realizing general nanophotonic circuits and a large variety of derived novel devices.