Large object distance and super-resolution graded-index photonic crystal flat lens

Ultratransparent photonic crystals realize positive and negative refractions

“…In contrast, dielectric-based photonic crystal (PC) [21,22] is more suitable for working in the optical frequency range due to its low loss characteristics [23]. Moreover, PC flat lenses can be widely used in super-resolution imaging [24][25][26][27], terahertz hollow * Author to whom any correspondence should be addressed.…”

Super-resolution imaging of negative-refractive graded-index photonic crystal flat lens

“…Later, more and more studies pointed out that the PC can gradually adjust the radius of the air holes [15,16], lattice constant [14,17,18] and material parameters [19] to achieve the gradual change of the internal effective refractive index. And GPC have been studied extensively for focusing [15][16][17][20][21][22], selfcollimation [19], superbending [23] and waveguide [24,25]. Cen et al proposed a GPC flat lens which can realize the imaging of the point source and sub-wavelength focusing of the plane wave in the first, second and fifth bands [26].…”

Straight lined and circular interface states in sunflower-type photonic crystals

“…The PBG can be regulated by properly designing the material and structural parameters of PCs, in this way, the propagation of electromagnetic waves can be controlled effectively in correlative devices. Many applications are derived from this property, such as fibers [3][4][5][6][7][8][9][10][11][12][13], lens [14][15][16][17][18][19][20], sensors [21,22], filters [23], couplers [24], lasers [25], topological edge state devices [26], etc.…”