Fig. 2: Topological polarization singular lasing with paired radiation channel.
From: Topological polarization singular lasing with highly efficient radiation channel
a Band diagram of the topological polarization singular lasing along Γ-kx direction. The positions of two polarization singularities are highlighted by red circles in the second Brillouin zone. b Spontaneous emission and lasing emission of the device, which are pumped at ~0.96Pth (black), ~1.26Pth (blue), and ~5.70Pth (red) respectively. Pth: lasing threshold. c Angle-resolved spontaneous spectra at ~0.96Pth. The measured bands are broken at the positions of two polarization singularities indicated by arrows, because they do not carry energy to optical far field. d Angle-resolved lasing spectrum at ~1.26Pth. The lasing emission strongly localizes around two singularities indicated by arrows in both spectral and momentum dimensions. The emission at the positions of two paired radiation channels are substantially stronger than the singular channels.
