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

Abstract

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

Photonic crystals comprising selectively grown flat‐topped and sharp‐tipped GaN pyramids

“…Details of the angularly-resolved experiments used here are described in Ref. [5]. All the measurements were performed at room temperature.…”

“…Photonic crystal (PhC) slabs based on III-nitride semiconductors with periods comparable to the optical wavelength of the emission or excitation are promising structures for improving the extraction efficiency of LEDs [1][2][3][4], for enhancing nonlinear optical processes such as second-and third-harmonic generation [5,6], and for optical rectification for terahertz pulse generation [7]. In these contexts, PhCs offer various degrees of freedom for device design and optimisation.…”

Overview of Nonlinear Optics

“…A different approach uses photonic crystal waveguides, which can be tuned to achieve phase-matching for SHG (Martorell, 1997;Broderick, 2000;Mondia, 2003;Torres 2004). …”

Selective growth of GaN on sapphire substrates treated with focused femtosecond laser pulses

“…Such periodical microstructures, for example GaN-air photonic crystals, have been previously fabricated, and nonlinear optical processes such as second-harmonic generation (SHG) [12] has been carried out. Especially, difference frequency generation (DFG) would be useful for realizing a robust and bright mid-infrared light source (l45 mm; ''fingerprint region''), since GaN is characterized by its chemical stability, thermal stability, wide transparency window (0.365-13 mm) [13], and the operation at room temperature.…”