Optimization of optical waveguide antennas for directive emission of light

TL;DR

This paper presents a numerical optimization of optical traveling wave antennas using full-wave simulations and particle swarm algorithms to achieve highly directive emission with various dielectric materials and geometries.

Contribution

It introduces a comprehensive optimization approach for dielectric optical antennas, analyzing mode behavior, radiation patterns, and bandwidths for improved directivity.

Findings

Optimized antennas exhibit highly directional emission due to guided TE modes.

Designs with Hafnium dioxide or Silicon achieve robust, tunable directivity.

Analysis reveals the dominant role of end-facet emission from the director.

Abstract

Optical travelling wave antennas offer unique opportunities to control and selectively guide light into a specific direction which renders them as excellent candidates for optical communication and sensing. These applications require state of the art engineering to reach optimized functionalities such as high directivity and radiation efficiency, low side lobe level, broadband and tunable capabilities, and compact design. In this work we report on the numerical optimization of the directivity of optical travelling wave antennas made from low-loss dielectric materials using full-wave numerical simulations in conjunction with a particle swarm optimization algorithm. The antennas are composed of a reflector and a director deposited on a glass substrate and an emitter placed in the feed gap between them serves as an internal source of excitation. In particular, we analysed antennas with rectangular- and horn-shaped directors made of either Hafnium dioxide or Silicon. The optimized antennas produce highly directional emission due to the presence of two dominant guided TE modes in the director in addition to leaky modes. These guided modes dominate the far-field emission pattern and govern the direction of the main lobe emission which predominately originates from the end facet of the director. Our work also provides a comprehensive analysis of the modes, radiation patterns, parametric influences, and bandwidths of the antennas that highlights their robust nature.