High-quality porous-silicon buried waveguides

This letter reports a method to produce porous-silicon waveguides by means of a laser local oxidation process. The estimated losses of the waveguides are below 1 dB/cm. This demonstrates the applicability of this material in integrated optics and telecommunications. Moreover, our results disclose the opportunity to integrate optoelectronic devices onto Si substrates. The laser writing method is achievable at low laser power, thus it is highly efficient and achievable with the standard equipment present in most laboratories. Another advantage is that oxidation is achieved without heating the complete chip, thus simplifying the integration process, i.e., the oxidation is inherently local through the direct-write process. This method opens the opportunity to build microstructures, like channel and membrane filters, in a flexible manner by R&D laboratories.