GaN Photonic Crystal Research Articles

Giant second-harmonic generation in a one-dimensional GaN photonic crystal

In order to determine the angular geometry that satisfies quasi-phase matching conditions for enhanced second-harmonic generation (SHG), the equi-frequency surfaces of the resonant photonic modes (that lie above the light line) of a one-dimensional GaN photonic crystal have been experimentally and theoretically studied as a function of frequency, angle of incidence, and azimuthal direction. Enhancement of the SHG has been observed when the angular configuration satisfies the quasi-phase matching conditions, i.e., when both the fundamental and second-harmonic fields coincide with resonant modes of the photonic crystal. The SHG enhancement achieved to the double resonance was 5000 times with respect to the unpatterned GaN layer. A smaller, but still substantially enhanced SHG level was also observed when the fundamental field is coupled into a resonant mode, while the second-harmonic field is not.

Giant second‐harmonic generation due to quasi‐phase matching in a one‐dimensional GaN photonic crystal

AbstractWe have demonstrated the giant enhancement of second‐harmonic generation in a one‐dimensional GaN photonic crystal structure caused by the simultaneous achievement of strong fundamental field confinement and quasi‐phase matching conditions. We have firstly measured the linear dispersive properties of the resonant modes for various azimuthal directions to predict the quasi‐phase matching conditions. The theory based on a rigorous scattering matrix method has provided a good description of the equi‐frequency surfaces. We have then shown that the equi‐frequency surfaces may be used to identify the angular situations for which the quasi‐phase matching conditions can be satisfied. The SHG enhancement achieved due to the double resonance was 5000 times greater than for the unpatterned GaN layer. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Equifrequency surfaces in GaN/sapphire photonic crystals

Photonic crystals are a new class of materials where photonic band gaps, large dispersion and anisotropy occur. By exploiting these properties GaN photonic crystals should have important potential for optoelectronic applications, principally in the areas of high-efficiency light emitters and second-harmonic generators. We present measurements of the equifrequency surfaces of the radiative Bloch modes for a photonic crystal etched in a GaN/sapphire film. The photonic band structure is calculated by using a scattering matrix method that reproduces well the anisotropy of the equifrequency surfaces exhibited by the photonic crystal.

Fabrication of GaN photonic crystals for 400 nm wavelength

We report on results of the fabrication and the micro-reflectance measurement of GaN photonic crystals. The etching performance of GaN has been studied with a conventional reactive ion etching system and SiCl 4 plasma. We obtained an etch rate of 100 nm/min and etching depth of 600 nm for dense GaN pillars. With graphite lattice of 270 nm period we observed a high reflection peak in the region of 400 nm wavelengths, depending strongly on the incident light polarization, which is in a good agreement with the theoretical calculation.