Open AccessEfficient second harmonic generation in low-loss planar GaN waveguides
Author(s) -
Maksym Gromovyi,
J. Brault,
Aimeric Courville,
S. Rennesson,
F. Sèmond,
G. Feuillet,
Pascal Baldi,
P. Boucaud,
JeanYves Duboz,
Marc de Micheli
Publication year - 2017
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.023035
Subject(s) - materials science , optics , planar , cladding (metalworking) , optoelectronics , second harmonic generation , sapphire , broadband , wavelength , energy conversion efficiency , laser , physics , computer graphics (images) , computer science , metallurgy
We demonstrate low-loss GaN/AlGaN planar waveguides grown by molecular beam epitaxy on sapphire substrates. By using a proper AlGaN cladding layer and reducing surface roughness we reach <1dB/cm propagation losses at 633nm. These low propagation losses allow an efficient second harmonic generation using modal phase matching between a TM0 pump at 1260nm and a TM2 second harmonic at 630nm. A maximal power conversion of 2% is realized with an efficiency of 0.15%·W -1 cm -2 . We provide a modelling that demonstrates broadband features of GaN/AlGaN platform by showing second harmonic wavelengths tunability from the visible up to the near-infrared spectral region. We discuss drawbacks of modal phase matching and propose a novel solution which allows a drastic improvement of modal overlaps with the help of a planar polarity inversion. This new approach is compatible with low propagation losses and may allow as high as 100%·W -1 cm -2 conversion efficiencies in the future.