Polymer based nano- and micro-photonic devices for three-dimensional optical interconnects



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The demand for higher bandwidth and higher speed driven by semiconductor technology development draws a great deal of research efforts devoted to the development of high speed data communication. Challenges on electrical copper interconnects at high frequency make optical interconnect technologies become a promising alternative to conventional electrical interconnects at different levels. This doctoral dissertation describes polymer based nano- and micro-photonic devices for three-dimensional optical interconnects. Two areas are focused, (1) polymer based two-dimensional (2D) and three-dimensional (3D) photonic crystal fabrication and simulation for laser beam steering applications, (2) polymer based optical waveguide array and shared bus waveguide with embedded 45° micro-mirrors for board level optical interconnects. A three-dimensional (3D) face-centered cubic (FCC) type polymer based photonic crystal using the polymer material SU-8 was simulated and successfully fabricated using a polygonal prism based holographic fabrication method. The theoretical study of polymer based photonic crystals was carried out for laser beam steering, which is based on the superprism effect. Horizontally stacked two-dimensional (2D) photonic crystal was fabricated by a double exposure holographic interference method. The k-vector superprism effect, the principle for beam steering, was studied in detail through EFC (Equi-frequency Contour) analysis. A polymer based optical waveguide array with embedded 45° micro-mirrors for board level optical interconnects was prepared using a Ni metal hard mold by a UV imprint technique. A nickel based metal mold with 45º tilted surfaces on both ends of the channel waveguide was prepared through the electroplating process. To obtain a precise 45º tilted angle, a 50µm thick SU-8 layer was exposed under de-ionized water. High speed optical testing (10Gb/s) was carried out on the polymeric optical waveguide array with embedded 45º micro-mirrors on flexible substrate for out-of-plane optical interconnects. A polymer based 3-to-3 shared optical bus waveguide with opposite 45º micro-mirrors was designed and fabricated using the metallic hard mold method. The Ni metal hard mold was successfully prepared using the Ni electroplating method. This metallic hard mold provides a convenient way to fabricate the polymeric optical bus waveguide devices through the imprint technique.