Fig. 2: Principle of optical vortex control.
From: Realization of all-optical vortex switching in exciton-polariton condensates
a–d Polariton density in μm−2 and e–h phase distribution in radians of vortices for different excitation settings. The vortex in a, e forms for excitation with only the ring-shaped CW pump with a profile as indicated by the white dashed circle. When in addition to the ring-shaped CW pump a Gaussian control beam is switched on as indicated by the white spots, an oscillating dipole mode is created as shown in b, f and c, g at different points in time. d, h When the additional control beam is switched off again, the system returns to a vortex mode, however, with a rotation direction of the vortex that depends on the point in time at which the control is switched off. Here, panel d shows a successful vortex switching event with the vortex charge inverted after perturbation by the control beam as is apparent from the phase profiles in e and h. The gradient of the phase distribution defines the local flow direction of the condensate.
