Fig. 3: Coherence and far-field patterns of the laser emission
From: Room-temperature lasing from nanophotonic topological cavities
a–d Experimental study of the coherence of the emission observed in Fig. 2d. a, c When two emission spots are isolated, b, d interference fringes are observed in Fourier space. e, f Real space emission distribution and Fourier-space emission directionality from an isolated cavity corner. An experimentally observed donut-like directionality pattern suggests an optical singularity hosted by the laser beam
