Gallium-nitride (GaN) is a promising material platform for integrated electro-optic devices due to its wide direct bandgap, pronounced nonlinearities and high optical damage threshold. Low-loss ridge waveguides in GaN layers were recently demonstrated. In this work we provide a first report of four-wave mixing in a GaN waveguide at telecommunication wavelengths, and observe comparatively high nonlinear propagation parameters. The nonlinear coefficient of the waveguide is measured as 1.6±0.45 [Wm] -1 , and the corresponding third-order nonlinear parameter of GaN is estimated as 3.4±1e-18 [m 2 /W]. The results suggest that GaN waveguides could be instrumental in nonlinear-optical signal processing applications.

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We report the fabrication and characterization of GaN/AlGaN ridge waveguides (WG). The "ridge" design was chosen to ensure low propagation loss. The fabrication process included four steps that could be easily regulated. GaN and AlGaN cladding layers were grown on a sapphire substrate by MOCVD. Shallow ridges were formed in the top cladding layer using ICP-RIE. After etching, samples were diced and WG facets were formed by polishing the samples opposite sides. The propagation loss at 1.56 mm was evaluated by measuring Fabry-Perot resonances from end-facet reflections. Losses as low as 1 dB/cm were measured for single mode WGs. Such low-loss two-dimensional WG could advance the use of GaN in integrated optoelectronics wave guiding components.Schematic illustration of GaN ridge WG structure (left) and a SEM image of a 10 mm wide ridge WG structure (right).

A molecular beam epitaxy-grown InGaAsSb p–n photodetector lattice matched to GaSb for extended short wave infrared is reported. Electrical and optical characteristics were analyzed at temperatures from 200 K to room temperature. The photodetectors exhibit dark current densities of 2.9 × 10−6 A/cm2 at 200 K and 4.6 mA/cm2 at 300 K (−0.1 V bias) and a high quantum efficiency of 73% at room temperature under front side illumination. High detectivity (D*) values of 2.2 × 1010 cm·Hz1/2 W−1 and 7.4 × 1011 cm·Hz1/2 W−1 were observed at 200 K and room temperature, respectively.