Exciton-polaritons are hybrid light-matter quasi-particles arising from the strong cou- pling of the optical mode of a semiconductor microcavity with the excitonic resonance of a quantum well (QW) $^{1}$. Several recent proposals have highlighted the potential of tailoring polariton wavefunctions by lateral in-plane confinement for applications in optelectronics devices and quantum information processing $^{2–4}$. In this paper, we experimentally demon- strate that by combining specific in-plane confinement with selective resonant excitation, we can realize in a controlled way polariton quantized vortices. In opposition to the vor- tices that spontaneously appear in the Bose-condensed phase of quasi-2D polaritons $^{5}$, our polaritons vortices are the result of optical vortices strongly coupled with the excitonic reso- nance. Generation of optical vortices has been demonstrated in different types of lasers like ring resonators $^{6}$, microchip solid state lasers7 and Vertical Cavity Surface Emitting Lasers (VCSELs) $^{8}$. They have been identified as the transverse modes of cylindrically symmetric optical resonators and often called the TEM$_{01}$ ∗ “donut” mode, which can be obtained as a superposition of the TEM$_{10}$ and TEM$_{01}$ modes $^{9,10}$. 

Cylindrically symmetric polariton traps can be obtained through lateral in-plane confine- ment by etching micropillars 11 or patterning mesas on the microcavity spacer $^{12}$. In both types of structure, strong coupling between the confined electromagnetic modes of the cylin- drical resonator with the excitonic resonance has been observed, demonstrating the creation of 0D polaritons. Although the confinement potential is acting on the photonic part of the polariton, the strong coupling regime results in the confinement of the whole polariton state, including the excitonic part $^{13}$. 

Our sample is a patterned GaAs λ − cavity with one embedded InGaAs QW, sandwiched between two semiconductor distributed bragg reflectors (DBRs), featuring a vacuum Rabi splitting of 3 . 5 meV . The polariton traps consist of circular mesas that were etched on the microcavity spacer. Discrete confined polariton states have been observed in traps with diameters varying between 3 µm and 20 µm $^{13,14}$. A spatially resolved spectrum of the photoluminescence emitted by the confined states in a 10 µm diameter trap under non- resonant pumping is shown in Fig. 1 (a). Discrete eigenstates can be observed for the lower polariton branch (below 1 . 484 eV ) and the upper polariton branch (above 1 . 484 eV ). The linewidth of these states is of the order of 80 µeV . All further measurements presented in the paper were performed on lower polariton states confined in mesas of 10 µm diameter, and for a detuning of δ ∼ 0 meV between the confined photonic mode and the excitonic 

