Kazuaki Sakoda

Numerical study on localized defect modes in two-dimensional triangular photonic crystals

The eigenfrequencies and eigenfunctions of localized defect modes in two-dimensional triangular photonic crystals composed of circular dielectric rods were calculated by means of the numerical simulation of the radiation process of a virtual oscillating dipole moment. In addition to the excellent agreement between our result and the experimental observation by Smith et al. [J. Opt. Soc. Am. B 10, 314 (1993)], we could evaluate the dependence of the eigenfrequency on the size of the supercell used in the numerical calculation. The result was also compared with that of the plane-wave expansion method.

Numerical analysis of the interference patterns in the optical transmission spectra of a square photonic lattice

The interference patterns in the transmission spectra of a two-dimensional square photonic lattice calculated by the plane-wave expansion method are compared with its photonic band structure in detail. The effective refractive indices obtained by both calculations correspond to each other quite well. In addition, aperiodic and singular interference patterns are found when the incident plane wave excites two eigenmodes with mutually different wave vectors.

Laser action characteristic of a two-dimensional photonic lattice

We observed a new type of laser action from optically pumped dye-molecules in solution filled in air-rods of a two-dimensional (2D) photonic lattice with the lattice constant a of /spl sim/1 /spl mu/m. The original lattice is composed of a parallel array of 1.0-mm-long air-rod cylinders of 0.66 to 0.90 /spl mu/m diameter (d) in a background material of PbO glass. The intersections of the rods with a perpendicular plane form a 2D triangular lattice; the lattice of a quasi-circular bundle with 1.3-1.5 mm size, of many hexagonal arrays, is supported by another PbO glass. The experiments were performed on two samples of such a photonic lattice with the air-rods filled with solution containing sulforhodamine-B dye in DMSO. The sample was optically pumped homogeneously along the rods by using a SHG beam of a pulsed Nd-YAG laser, and the radiation was detected in the lateral direction. We calculated the corresponding photonic band structure. The results reveal that reflecting the small difference of the relevant refractive indices between the PbO glass and the solvent, no significant bandgap is open in any direction, but there are a few special frequencies where the band dispersion is almost flat over the Brillouin zone, indicating that the density of photonic states is high, or the group velocity is very slow. Furthermore, there are many uncoupled bands that cannot couple to the external plane waves for symmetry reason; therefore those bands should have a high Q-value. With the help of the calculated results, we tentatively interpret the mechanisms as follows. The slow group velocity causes the lasers at 610 and 639 nm, while the uncoupled modes are responsible for the laser at 603 nm.

Laser Oscillation From Dye Molecules In A 2d Photonic Crystal

The size of optical devices is limited to the wavelength order (e.g., micro-millimeter range) due to the diffraction limit. To realize optical devices in nanometer size we have studied two-dimensional (2D) optical waveguides using surface plasmon polariton (SPP) which is a surface wave localizing at metal/dielectric interface.’ SPP is considered to be 2D optical wave since its k vector has two real components. In this article, we propose principally new optical phase modulators and detectors using SPP in nanometer size. We analyze their properties theoretically and find that the half-wave voltage V, of the modulator is much lower than that of the conventional one. First, we describe 2D optical waveguides. 2D optical waveguide with electro-optical (EO) core are shown in the inset of Fig. 1. EO material is used to control the device electrically It is known that there is two Fano modes (coupled SPP modes) in metal gaps and the beam thickness of asymmetric mode can be decreased below the wavelength in free

New method to calculate photonic band structures with frequency-dependent dielectric constants

Summary form only given. Dispersion relations of photonic crystals with spatially periodic dielectric constants that do not depend on frequency have been calculated with sufficient accuracy by means of the plane-wave expansion method. But Kuzmiak et al. (1994) showed that this method does not always give good convergence when the dielectric constant depends on frequency. On the other hand, the present authors and his coworkers reported that the eigenfrequencies and eigenfunctions of localized mid-gap modes originating from the defects in the photonic crystals can be calculated accurately by solving numerically the Maxwells equations with a virtual oscillating dipole moment embedded in the crystals as a source term. In the paper, we extend this method to deal with regular crystals with frequency-dependent dielectric constants and apply it to a two-dimensional square lattice composed of metal cylinders.

Localized eigenmodes in a two-dimensional square photonic lattice

seen in both PLE spectra suggests that in addition to a carrier mediated process, Er3+ ions can also be excited through direct optical excitation of an intra-4f transition. The work at Hampton University was supported by the Army Research Office through Grant DAAH04-96-1-0089 and by NASA through Grant NAGW-2929. *Department ofMaterials Science and Engineering, University of Florida, Gainsville, Florida 3261 1 **Hughes Research Laboratory, Malibu, California 90265 t U. S. Army Research Ofice, Research Triangle Park, North Carolina 27709