Generation of over 1000 Diffraction Spots from 2D Graded Photonic Super-Crystals

Photonics

Hualiang Zhang¹  Khadijah Alnasser²  Usha Philipose²  Safaa Hassan²  Yan Jiang²  Yuankun Lin²  Noah Hurley² 

[1] Department of Electrical & Computer Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA;Department of Physics, University of North Texas, Denton, TX 76203, USA;

关键词: graded index photonic crystal;    graded photonic super-crystal;    diffraction;    E-beam lithography;    electromagnetic simulation;   

DOI  :  10.3390/photonics7020027

来源: DOAJ

【 摘 要 】

For the first time, we are able to generate over 1000 diffraction spots from a graded photonic super-crystal with a unit super-cell size of 12a × 12a where a is the lattice constant and hole radii are gradually changed in dual directions. The diffraction pattern from the graded photonic super-crystal reveals unique diffraction properties. The first order diffractions of (±1,0) or (0,±1) disappear. Fractional diffraction orders are observed in the diffraction pattern inside a square with vertices of (1,1), (1,−1), (−1,−1) and (−1,−1). The fractional diffraction can be understood from lattices with a period of a. However, a dual-lattice model is considered in order to explain higher-order diffractions. E-field intensity simulations show a coupling and re-distribution among fractional orders of Bloch waves. There are a total of 12 × 12 spots in E-field intensity in the unit supercell corresponding to 12 × 12 fractional diffraction orders in the diffraction pattern and 12 × 12 fractional orders of momentum in the first Brillouin zone in k-space.

【 授权许可】

Unknown