Low-loss silicon wire waveguides for optical integrated circuits

Low-propagation-loss silicon wire waveguides are key components of optical integrated circuits. In this paper, we clarified, through assessment of the relationship between waveguide loss and fabrication technology that high-resolution lithography and an adjusted lithography process window are important for low-loss waveguides. The silicon wire waveguides fabricated by high-resolution lithography technology using ArF immersion lithography process showed world-record low propagation losses of 0.40 dB/cm for the C-band and 1.28 dB/cm for the O-band. Analysis with Barwicz and Haus's theory indicated that sidewall scattering is the main cause of propagation loss even in such low-loss waveguides.