We report on the fabrication and characterization of low-loss, single-mode GaN-InAlN rib waveguides. The entire
waveguide is lattice matched to GaN and is grown by metalorganic vapor phase epitaxy. Waveguide bars are characterized
at 1.55μm wavelength using a lensed silica fiber. Propagation losses of samples with diced facets were measured by the
cut-back method to be < 3dB/mm for very wide waveguides. A second series with dry-etched facets shows insertion loss of
15 dB. By evaluating the contrast in Fabry-Perot fringes in spectra from 1.5-1.58μm the propagation loss is determined
to be as low as 1.8 dB/mm for TE and 4.7 dB/mm for TM. Such waveguides should be useful in integrated guided-wave intersubband components.
Wavelength dependent propagation losses in GaN/InAlN waveguides