Equifrequency surfaces in a two-dimensional GaN-based photonic crystal.
We established the angular conditions that maintain the quasi-phase matching conditions for enhanced second-harmonic generation. To do that, we investigated the equifrequency surfaces of the resonant Bloch modes of a two-dimensional periodic, hole-array photonic crystal etched into a GaN/sapphire epitaxial structure. The equifrequency surfaces exhibit remarkable shapes, in contrast to the simpler surfaces of a one-dimensional structure. The observed anisotropy agrees well with the surfaces calculated by a scattering matrix method. The equifrequency surfaces at fundamental and second-harmonic frequencies provide the values of polar and azimuthal angles that maintain quasi-phase matching conditions for enhanced second-harmonic generation over an extended tuning range. The predicted values for quasi phase-matching conditions show that frequency tuning for the two-dimensional case covers an about two times larger fractional bandwidth relative to the one-dimensional case.
Coquillat
D
D
Torres
J
J
Peyrade
D
D
Legros
R
R
Lascaray
J
J
Le Vassor d'Yerville
M
M
Centeno
E
E
Cassagne
D
D
Albert
J
J
Chen
Y
Y
De La Rue
R
R