Silicon-based horizontal nanoplasmonic slot waveguides for on-chip integration

Horizontal metal/insulator/Si/insulator/metal nanoplasmonic slot waveguide (PWG), which is inserted in a conventional Si wire waveguide, is fabricated using the standard Si-CMOS technology. A thin insulator between the metal and the Si core plays a key role: it not only increases the propagation distance as the theoretical prediction, but also prevents metal diffusion and/or metal-Si reaction. Cu-PWGs with the Si core width of similar to 134-21 nm and similar to 12-nm-thick SiO2 on each side exhibit a relatively low propagation loss of similar to 0.37-0.63 dB/mu m around the telecommunication wavelength of 1550 nm, which is similar to 2.6 times smaller than the Al-counterparts. A simple tapered coupler can provide an effective coupling between the PWG and the conventional Si wire waveguide. The coupling efficiency as high as similar to 0.1-0.4 dB per facet is measured. The PWG allows a sharp bending. The pure bending loss of a Cu-PWG direct 90 degrees bend is measured to be similar to 0.6-1.0 dB. These results indicate the potential for seamless integration of various functional nanoplasmonic devices in existing Si electronic photonic integrated circuits (Si-EPICs). (C) 2011 Optical Society of America