title: Low-contrast bandgaps of a planar parabolic spiral lattice.
abstract: We show that a planar aperiodic lattice, mimicking the appearance of a sunflower, supports photonic bandgaps for weak dielectric contrast. The pattern's high orientational order and spatially uniform modal pitch yields an isotropic Fourier space. A 2D structure of cylinders (=2) in air possesses a wide 21% TM bandgap, versus 5.6% for a sixfold lattice or 14% for a 12-fold fractal tiling. The isotropic gap frequencies imply flat bands, and thus application in nonlinear optics and low threshold lasers, where a reduced group velocity in all directions may be desired.
authors.affiliation: Nano Research Group, School of Electronics and Computer Science, University of Southampton,Southampton, SO17 1BJ, UK. mep06r@ecs.soton.ac.uk
authors.forename: Michael E
authors.initials: ME
authors.lastname: Pollard
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Parker