Fine embossing of chalcogenide glasses – a new fabrication route for photonic integrated circuits

Abstract

For the first time embossing of ribs, from 1 to 10μm wide and ∼10mm long, has been carried out in chalcogenide glass layers sputtered onto semiconductor wafer substrates, with potential to act as monomode waveguides; these features have been similarly embossed in the surface of bulk chalcogenide glasses. The embossing shows very good replication of the GaAs mould patterning to 1μm definition, with evidence also for sub-micron replication. For the embossing, thin coatings of the chalcogenide glasses were sputtered onto wafer substrates as follows: (i) a 6μm layer of Ge17As18Se65 (at.%) onto porous Si-on-Si wafer substrates and (ii) a 4μm layer of Ge15As15Se17Te53 onto uncoated GaAs substrates. The Ge17As18Se65 sputtered glass layer on porous Si-on-Si was demonstrated to slab waveguide at 1.55μm wavelength; it was designed to achieve monomode waveguiding at 1.55μm after embossing, for the 5μm wide rib. The series of ribs, 1–10μm wide, were successfully embossed in the Ge17As18Se65 glass sputtered layer on porous Si-on-Si, but cracking of the glass layer occurred during the embossing process. Successful embossing of ribs without the glass layer cracking was achieved for the Ge15As15Se17Te53 sputtered glass layer on uncoated GaAs. Due to its relative simplicity, it is likely that hot embossing of this type of glass-based matrix offers an extremely promising route for producing high-resolution, guided-wave optical components and circuitry at low-cost, high-volume, and for a wide wavelength range.