Figure 2.

Bessel beams achieved by the selective excitation of the inequivalent valley states. (a) Zoomed-in schematic (left panel) and radiated pressure fields in free space (right panel) of the LCP chiral source. (b) Distributions of the absolute pressure fields of the triple non-diffracting Bessel beams excited by the central LCP source. White rhombuses represent the BFZ. (c) k-space analysis on the formation of the left BFZ labeled as the solid white rhombus in (b). Black solid hexagon represents the 1st BZ and the black dashed circle shows the dispersion in background. Shadow region represents the SC, of which the cyan lines are for the interfaces. Purple arrows represent the radiation angles out of the SC. (d) Phase patterns of the K₁ valley state in the SC when applying the LCP chiral source. (e)–(h) Corresponding analysis on the formation of BFZ by using the RCP chiral source.