Lattice-Matched GaN–InAlN Waveguides at λ = 1.55 <i>μ</i>m Grown by Metal–Organic Vapor Phase Epitaxy

We report on the demonstration of low-loss, single-mode GaN-InAlN ridge waveguides (WGs) at fiber-optics telecommunication wavelengths. The structure grown by metal-organic vapor phase epitaxy contains AlInN cladding layers lattice-matched to GaN. For slab-like WGs propagation losses are below 3 dB/mm and independent of light polarization. For 2.6-<i>μ</i>m-wide WGs the propagation losses in the 1.5- to 1.58-<i>μ</i>m spectral region are as low as 1.8 and 4.9 dB/mm for transverse-electric- and transverse-magnetic-polarization, respectively. The losses are attributed to the sidewall roughness and can be further reduced by the optimization of the etching process.