Browsing by Author "Jia, Lin"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Impact of Geometry on the TM Photonic Band Gaps of Photonic Crystals and Quasicrystals(American Physical Society, 2011) Jia, Lin; Bita, Ion; Thomas, Edwin L.Here we demonstrate a novel quantitative procedure to pursue statistical studies on the geometric properties of photonic crystals and photonic quasicrystals (PQCs) which consist of separate dielectric particles. The geometric properties are quantified and correlated to the size of the photonic band gap (PBG) for wide permittivity range using three characteristic parameters: shape anisotropy, size distribution, and feature-feature distribution. Our concept brings statistical analysis to the photonic crystal research and offers the possibility to predict the PBG from a morphological analysis.Item Optical forces and optical torques on various materials arising from optical lattices in the Lorentz-Mie regime(American Physical Society, 2011) Jia, Lin; Thomas, Edwin L.By combining the Maxwell stress tensor with the finite-difference time-domain (FDTD) method, we calculate the optical force and optical torque on particles from optical lattices. We compare our method to the two-component method and the electrostatic approximation (ESA). We also discuss how particle's refractive index, shape, size, and the morphology of an optical lattice influence optical forces and the condition to form stable optical trapping wells. In addition to optical forces, optical torque from one dimensional (1D) optical lattice is discussed for particles having anisotropic shapes; metastable and stable equilibrium orientation states are found. A detailed understanding of the optical force and torque from optical lattices has significant implications for optical trapping, micromanipulation, and sorting of particles.Item Photonic density of states of two-dimensional quasicrystalline photonic structures(American Physical Society, 2011) Jia, Lin; Bita, Ion; Thomas, Edwin L.A large photonic band gap (PBG) is highly favorable for photonic crystal devices. One of the most important goals of PBG materials research is identifying structural design strategies for maximizing the gap size. We provide a comprehensive analysis of the PBG properties of two-dimensional (2D) quasicrystals (QCs), where rotational symmetry, dielectric fill factor, and structural morphology were varied systematically in order to identify correlations between structure and PBG width at a given dielectric contrast (13:1, Si:air). The transverse electric (TE) and transverse magnetic (TM) PBGs of 12 types of QCs are investigated (588 structures). We discovered a 12mm QC with a 56.5% TE PBG, the largest reported TE PBG for an aperiodic crystal to date. We also report here a QC morphology comprising “throwing star”-like dielectric domains, with near-circular air cores and interconnecting veins emanating radially around the core. This interesting morphology leads to a complete PBG of ∼20% , which is the largest reported complete PBG for aperiodic crystals.Item Two-pattern compound photonic crystals with a large complete photonic band gap(American Physical Society, 2011) Jia, Lin; Thomas, Edwin L.We present a set of two-dimensional aperiodic structures with a large complete photonic band gap (PBG), which are named two-pattern photonic crystals. By superposing two substructures without regard to registration, we designed six new aperiodic PBG structures having a complete PBG larger than 15% for ɛ2/ɛ1=11.4. The rod-honeycomb two-pattern photonic crystal provides the largest complete PBG to date. An aperiodic structure becomes the champion structure with the largest PBG. Surprisingly, the TM and TE gaps of a two-pattern photonic crystal are much less interdependent than the PBGs of conventional photonic crystals proposed before, affording interesting capabilities for us to tune the TM and TE PBGs separately. By altering the respective substructures, optical devices for different polarizations (TE, TM, or both) can readily be designed.