InN-Based Optical Waveguides Developed by RF Sputtering for All-Optical Applications at 1.55

We report on the design, fabrication, and optical characterization of InN-based optical waveguides aiming at their application as all-optical limiters at 1.55 μm. The InN guiding layers are grown by radio frequency (RF) sputtering on sapphire substrates. Experimental cutback method and nonlinear optical transmittance measurements were performed for the developed devices. The waveguides present nonlinear behavior associated with two photon absorption process. A nonlinear absorption coefficient ranging from ~43 to 114 cm/GW is estimated from optical measurements. These results open the possibility of using RF sputtering as a low cost and thermally harmless technique for the development and overgrowth of InN-based optical waveguides in future III-nitride all-optical integrated circuits working at telecom wavelengths.