Pseudospin plays a central role in many novel physical properties of graphene and other artificial systems which have pseudospins of . Here we show that in certain photonic crystals (PCs) exhibiting conical dispersions at , the eigenmodes near the “Dirac-like point” can be described by an effective spin-orbit Hamiltonian with a higher dimension value , treating the wave propagation in positive index (upper cone), negative index (lower cone), and zero index (flat band) media within a unified framework. The three-component spinor gives rise to boundary conditions distinct from those of pseudospin , leading to wave transport behaviors as manifested in super Klein tunneling and supercollimation. For example, collimation can be realized more easily with pseudospin 1 than pseudospin . The effective medium description of the PCs allows us to further understand the physics of pseudospin-1 electromagnetic (EM) waves from the perspective of complementary materials. The special wave scattering properties of pseudospin-1 EM waves, in conjunction with the discovery that the effective photonic potential can be varied by a simple change of length scale, offer ways to control photon transport. As a useful platform to study pseudospin-1 physics, dielectric PCs are much easier to fabricate and characterize than ultracold atom systems proposed previously. The system also provides a platform to realize the concept of “complementary medium” using dielectric materials and has the unique advantage of low loss.
- Received 6 November 2015
DOI:https://doi.org/10.1103/PhysRevB.93.035422
©2016 American Physical Society
Condensed Matter & Materials Physics