Figure | Schematic diagram of DVM in the THz photonic crystal fiber. (IMAGE)
Caption
Figure | Schematic diagram of DVM in the THz photonic crystal fiber. Topological DVM exists in the mid-gap and is spectrally isolated from other bulk states over the whole Brillion zone in a photonic system. The DVM can be traced back to mid-gap Jackiw-Rossi zero energy that is the solution of the 2D Dirac equation with a topologically protected vortical mass term. If extending the height of a DVM topological cavity to acquire a nonzero out-plane wavevector, from local mode to propagating mode, a SPSM photonic crystal fiber can be realized to transmit the DVM. The fiber provides an ideal platform to support an ultra-broadband SPSM compared with conventional THz SPSM fibers, as long as DVM dispersion is inside the bandgap. Besides, the DVM possesses a relatively low confinement loss inheriting the property of the DVM that locates at Γ point without in-plane wavevector, while the bulk states exponentially decay into free space to guarantee the single-mode transmission.
Credit
Hongyang Xing et al.
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CC BY