Inverse Design of Whispering-gallery Nanolasers with Tailored Beam Shape and Polarization

Abstract: Control over the shape and polarization of the beam emitted by a laser source is important in applications such as optical communications, optical manipulation and high-resolution optical imaging. In this paper, we present the inverse design of monolithic whispering-gallery nanolasers which emit along their axial direction with a tailored laser beam shape and polarization. We design and experimentally verify three types of sub-micron cavities, each one emitting into a different laser radiation mode: an azimuthally polarized doughnut beam, a radially polarized doughnut beam and a linearly polarized gaussian-like beam. The measured output laser beams yield a field overlap with respect to the target mode of 92%, 96% and 85% for the azimuthal, radial and linearly polarized cases, respectively, thereby demonstrating the generality of the method in the design of ultra-compact lasers with tailored beams.