Different from previous investigations, Yiqi Zhang and co‐workers (see article number 2000015 ) develop a new kind of Dirac photonic lattice that possesses type‐II Dirac cones in the band structure intrinsically. In other words, the appearance of the type‐II Dirac cone is only dependent on ...
double and multiple phase matching in engineered structures with sign-varying second-order nonlinear susceptibility, including different types of QPM optical superlattices, noncollinear geometry, and two-dimensional nonlinear quadratic photonic crystals (which can be considered two-dimensional QPM lattices). ...
As an optical analogy, type㊣I Dirac photonic lattices have been also designed. Here, type㊣I Dirac cones are reported in Lieb﹍ike photonic lattices composed of identical waveguide channels, and the anisotropy of the band structure is due to neither the refractive index change nor the ...