(초청강연논문) Design and Fabrication of Micro/Nano-scale Plasmonic Waveguide Devices aimed for VLSI Photonic Circuit Application

초록

We present an overview of our work on the theory, design, fabrication, and integration of micro/nano-scale plasmonic waveguide devices for VLSI photonic integrated circuit applications. We examine the characteristics and use of the slow light propagation and the fast light propagation on the design of various functions. We design both horizontally parallel directional couplers and vertically parallel directional couplers and compare their performances. For this, we designed and fabricated vertical directional couplers consisting of metal stripe waveguides embedded in polymer. The fabricated vertical directional couplers were 9mm long in total length with the arm separation of 200um at the input/output section. We also designed and fabricated a novel metal-waveguide structure for sustaining long-range surface-plasmon-polaritons(LR-SPP), which is basically composed of two asymmetric metal layers. Mode cut-off of LR-SPPs excited on the asymmetric double-metal waveguides is characterized by their dispersion relations and mode profiles. We confirm experimentally the existence of low-loss, well-confined LR-SPP modes by measuring far-field outputs emerging from an edge of the asymmetric double-metal waveguides. We also fabricated several types of SPP waveguide devices including straight line, S-bend, Y-branch, and couplers for the gold strip patterns. The overall propagation loss of the asymmetric double-metal waveguides is comparable to that of single metal-strip waveguides. These plasmonic devices are then integrated with other micro/nano-photonic devices, either on a board on on a chip, for VLSI photonic integrated circuit applications. We will present examples of devices and integrated circuits along with the scientific and engineering issues arising from the various mismatches between devices of diverse functional characteristics and properties.