We propose and demonstrate reconfigurable microfiber-coupled photonic crystal (PhC) lasers. In this generic
configuration, the position of a PhC resonator can be defined (and redefined) repeatedly by simply relocating a curved
microfiber along the linear PhC waveguide. In the proximity of the PhC waveguide in contact with the microfiber, the
cutoff frequency (effective index) of the PhC waveguide becomes smaller (larger) than that of a bare PhC waveguide.
Accordingly, when a curved microfiber is in contact with the PhC waveguide, a linear PhC resonator having Gaussianshaped
potential well is formed. Experimentally we confirm the formation of the reconfigurable resonator by observing
laser operation slightly below three available band edges.
The efficiency of light emitting diode (LED) is limited because large amount of generated light is confined inside
of it by total internal reflection. A photonic crystal (PC) layer embedded in LED structure substantially modifies the
guiding properties inside the chip and prevents the lateral propagation of light, so that it largely increases the output
power of an LED. In this paper, we present both numerical and experiment studies on the enhancement of light
extraction of GaN-based light-emitting diodes (LEDs) with hexagonal PC layer. By finite difference time domain
(FDTD) simulation, the PC parameters were varied in order to evaluate the enhancement. Best extraction efficiency was
obtained with the lattice constant of 400 - 600 nm, the PC thickness of 150 - 200 nm and the ratio of hole radius to lattice
constant of 0.3 - 0.4 for the 465 nm LED based on GaN. Furthermore, hexagonal PC GaN-based LED was fabricated
using anodic aluminum oxide (AAO) method. The PC layer is located below quantum well active layer and the
efficiency was improved more than 20%. It was shown that these numerical results agree reasonably well with the
Lasing dynamics of photonic-crystal single-cell cavity is studied by Lorentz-dispersive Gain FDTD method. From hexapole mode of a photonic-crystal single-cell cavity, the generation of laser modes and the relaxation oscillation are observed.
The influence of etching slope on cavity Q-factors in two-dimensional (2D) photonic crystal (PhC) slab is studied. Through FDTD simulation, it is confirmed that the Q-factor decreases with etching slope. The main loss comes from the horizontal coupling into propagating TM-modes. We designed three-lattice-long modified linear cavities having high Q-factors. However, the measured Q-factor was about 250. This small Q-factor is attributed to the non-vertical (13°) side wall.
We fabricated the standing metallic nano-stripe array structure on the thin ITO layer with a very narrow width and a relative high height of the stripe by using the electron-beam lithography and Ar ion milling process. The polarization properties were investigated as the period and the incident angle are varied. In transmission spectra of the TE polarization, the resonance with Fano-like resonance was observed. In case of TM polarization, there's no resonance near normal incidence because the electric field is perpendicular to the very thin metallic grating.