Fig. 3: Direct imaging polarization singularities at lasing state.
From: Topological polarization singular lasing with highly efficient radiation channel
a Lasing emission pattern in momentum space. Two polarization singularities from the lasing mode appear as dark holes, and each of them has a paired radiation channel appearing as bright peak. b Three-dimensional full wave simulated lasing emission pattern in momentum space. The dashed squares in a, b indicate the boundary of the first Brillouin zone. c Simulated emission pattern superimposed with local polarization direction around a singularity and a radiation channel in momentum space. Arrows: polarization vectors indicating local electrical field polarization. d Direction of polarization vectors, where \(\phi\) is the angle of polarization vectors with respect to positive kx-axis in counter-clockwise orientation. e Lasing patterns in momentum space after a linear polarizer with varied polarization angles. Arrows: directions of the linear polarizer. f Simulated emission patterns with the same polarization states as in panel e.
