Volume 95, Issue 3, 01 February 2004
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
95(2004); http://dx.doi.org/10.1063/1.1636254View Description Hide Description
Anomalously strong diffraction from a bilayer lattice of dielectric microspheres, previously reported by the authors, has been attributed to the enhancement of diffraction by specular resonance in constituent bispheres. On the basis of rigorous calculations and experiments, specular resonance from bispheres is found to be dominant even in the scattering from a cluster of several microspheres. As a consequence, a diffraction model, in which a bilayer lattice of microspheres is viewed as a two-dimensional array of bispheres, is constructed. By incorporating the specular resonance into a diffraction theory of two-dimensional lattices as a structure factor, observed diffraction behavior is explained. In the diffraction from a bilayer lattice of microspheres, the specular resonance functions as a blazing mechanism. Possible configurations and suitable parameters for efficient gratings are discussed, and a self-assembled bilayer lattice of dielectric microspheres with a diameter 1.6–3.2 times as large as the wavelength is found to be promising as a low-cost and highly efficient transmission grating. The spheres can be replaced with cylinders or lenses. Tunable diffractiondevices with efficiency exceeding that of conventional gratings would be realized by microelectromechanical systems comprised of two optimally designed microlens arrays.
95(2004); http://dx.doi.org/10.1063/1.1635668View Description Hide Description
We develop a model to study coupled cavity waveguides (CCWs) in photonic crystals, composed of linear chains of coupled cavities. By extending previous work on single mode cavities, we have developed a model applicable to any finite number of quasi-degenerate cavity modes. Our model, which uses a multimode tight-binding approach, allows us to study the interaction between the cavity modes as well as the coupling between the CCW bands. In contrast to previous work the coupling parameters are calculated ab initio from the single cavity field profile. The calculated dispersion relations are shown to be in good agreement with those obtained from the plane wave expansion method.
95(2004); http://dx.doi.org/10.1063/1.1633337View Description Hide Description
Theoretical study of the optical diffractionproperties of holographicpolymer-dispersed liquid crystal (HPDLC)-based thick volume grating was presented. It is found that the HPDLC grating can selectively diffract the s-polarized light only, p-polarized light only, or both and beams by selecting suitable grating parameters. When an electric field is applied, the s- and p-polarized lights exhibit different diffraction behaviors and, thus, the tunable dual-state or three-state polarization switching could be realized.