Nonreciprocal subwavelength optical nanoantennas

Summary form only given. Optical nanoantennas have recently become an active field of research, offering a number of potential applications, including sensing, lasing, photovoltaics, and medical treatment. The functionality of an antenna is determined by the ability of a dynamic tuning of its radiation pattern, i.e. active beam steering, and on the ability to differentiate between transmitted and received signals. At microwave frequencies these conditions are achieved by the use of complex electronic and modular systems, for example, with the help of phase array antennas, or by applying signal processing tools. However, at optical frequencies such as visible, IR and THz wavelengths these well known techniques are not readily applicable. Furthermore, it is highly desirable to keep optical antenna dimensions below the subwavelength limit. Utilizing material response in optical nanoantenna engineering might provide additional degrees of freedom. In particular, magneto-optical materials provide additional nonreciprocal coupling between electric field components and can be tuned by an applied magnetic field.