Experimental demonstration of silicon slot waveguide with low transmission loss at 1064 nm

Silicon slot waveguides that can operate at the wavelength of high silicon absorption are experimentally demonstrated on SOI wafer. The measured transmission loss coefficient could be as low as 2.28±0.03 dB/mm at the wavelength of 1064 nm (the slot width of 100 nm), which is much lower than the absorption loss of silicon (5 dB/mm at 1064 nm). According to the simulation, such value is dominated by the surface roughness of sidewalls. The transmission loss is potentially to be reduced to <1 dB/mm if the sidewall roughness could be reduced to ~5 nm. We believe that this work could pave the way to achieving all silicon photonic integrated circuits, which are attractive for future optical interconnect and chemical/biological analysis.