Low-Loss Waveguide Fabrication by Inkjet Printing on Porous Silicon

We report fabrication of optical waveguides embedded in oxidized porous silicon in a maskless process. Patterned pore-filling was attained by means of inkjet printing, enabling lateral modification of the waveguide's index of refraction, and other optical properties, thus providing full two-dimensional refractive index control of the optical waveguide. The waveguides were created by applying a KDP salt solution over a porous silicon film by means of a material printer. Light guiding was demonstrated at wavelengths 1.064 and 1.550 μm. Measured values of the propagation loss at these wavelengths were 2.4 dB/cm and below 0.5 dB/cm, respectively.