Nanoplasmonic waveguides utilizing surface plasmon polaritons (SPPs) propagation have been investigated for more than 15 years and are now well understood. Many researchers make their efforts to find the best ways of using light and overcoming the speed limit of integrated circuits by means of SPPs. Here, we introduce the simulation results and fabrication technology of dielectric-metal-dielectric long-range nanoplasmonic waveguides, which consists of a multilayer stack based on ultrathin noble metals in between alumina thin films. Various waveguide topologies are simulated to optimize all the geometric and multilayer stack parameters. We demonstrate the calculated propagation length of L_prop = 0.27 mm at the 785 nm wavelength for the Al₂O₃/Ag/Al₂O₃ waveguides. In addition, we numerically show the possibility to eliminate signal cross-talks (less than 0.01%) between two crossed waveguides. One of the key technology issues of such waveguides’ nanofabrication is a dry, low-damage-etching of a multilayer stack with extremely sensitive ultrathin metals. In this paper, we propose the fabrication process flow, which provides both dry etching of Al₂O₃/Au(Ag)/Al₂O₃ waveguides nanostructures with high aspect ratios and non-damage ultrathin metal films patterning. We believe that the proposed design and fabrication process flow provides new opportunities in next-generation photonic interconnects, plasmonic nanocircuitry, quantum optics and biosensors.

A series of long-range plasmonic waveguides based on a thin three-layer Al $_2$ O $_3$ /gold/Al $_2$ O $_3$ film operating in the visible spectral range have been studied experimentally and theoretically. For long-range plasmonic waveguides having identical structure but different lengths, the propagation length of plasmonic waves was determined to be 250±15 μm at λ=765 nm and was in a very good agreement with the theoretical value obtained through numerical modeling. The demonstrated propagation length is the highest one for the gold film-based plasmonic waveguides described in the literature for a uniform (non-photonic-crystal) substrate in the UV, visible, and near IR (up to 1 μm) spectral ranges, which is due to high technological quality of the fabricated waveguides and optimized three-layer structure. The proposed waveguides could find applications in optical interconnects and guided-wave optical sensors.