  We report fabrication of optical waveguides embedded in oxidised porous
silicon in a mask-less 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
microns. Measured values of the intensity attenuation at these wavelengths were
2.5 dB/cm and below 1.3 dB/cm respectively
