title: High-density channel alignment of graded index core polymer optical waveguide and its crosstalk analysis with ray tracing method.
abstract: We fabricate graded index (GI) multi-channel polymer optical waveguides comprised of poly methyl methacrylate (PMMA)-poly benzyl methacrylate copolymer for the purpose of achieving high thermal stability in the GI profiles. The waveguides obtained show slightly higher propagation loss (0.033 dB/cm at 850 nm) than doped PMMA based GI-core polymer waveguides we have reported, due to the excess scattering loss inherent to the mixture of copolymer and homo-polymer in the core area. In this paper, we focus on the influence of the excess scattering loss on mode conversion and inter-channel crosstalk. We simulate the behavior of light propagating inside the core with and without the scattering effect. Using the simulation, the excess loss experimentally observed in the copolymer-core waveguide is successfully reproduced, and then, we find that the excess scattering loss of 0.008 dB/cm could increase the inter-channel crosstalk from -30 dB to -23 dB which agrees with the experimentally observed value. Although the simulation of the inter-channel crosstalk was performed only on our GI-core polymer optical waveguides, it is capable of modeling the conventional SI rectangular-core waveguides. Some amount of excess scattering is generally observed in the conventional SI-core waveguides, and thus, the application of this simulation to SI-core waveguides allows a feasible design for high-density alignment of the waveguides.
authors.affiliation: Graduate School of Science and Technology, Keio University, Kohoku-ku, Yokohama, Japan. hhhsu@z6.keio.jp
authors.forename: Hsiang-Han
authors.initials: HH
authors.lastname: Hsu
authors.forename: Takaaki
authors.initials: T
authors.lastname: Ishigure
mesh_terms: D004581:Electronics / Q000379:methods*; D008027:Light; D008853:Microscopy; D008962:Models, Theoretical; D011109:Polymethacrylic Acids / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012031:Refractometry; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D011109:Polymethacrylic Acids; C098156:polybenzylmethacrylate; D019904:Polymethyl Methacrylate