Fabrication of Mach-Zehnder optical waveguide structures in PDMS thin films using proton beam writing

プロトン・ビーム・ライティングによるPDMS薄膜内のマッハツェンダー光導波路構造の製作

狩野 圭佑*; 猿谷 良太*; 川端 駿介*; 新木 潤*; 野口 克也*; 加田 渉*; 三浦 健太*; 加藤 聖*; 佐藤 隆博; 江夏 昌志; 石井 保行; 神谷 富裕; 西川 宏之*; 花泉 修*

Kano, Keisuke*; Saruya, Ryota*; Kawabata, Shunsuke*; Araki, Jun*; Noguchi, Katsuya*; Kada, Wataru*; Miura, Kenta*; Kato, Hijiri*; Sato, Takahiro; Koka, Masashi; Ishii, Yasuyuki; Kamiya, Tomihiro; Nishikawa, Hiroyuki*; Hanaizumi, Osamu*

Proton beam writing (PBW) has been applied to fabricate Mach-Zehnder (MZ) optical waveguides which is expected to be an optical switch with small power consumption, because only one processing of PBW enables us to fabricate such waveguides even inside of plastic materials. Such waveguides were fabricated in thin poly-methyl-methacrylate (PMMA) films by PBW. However, they had low transmittance. In order to fabricate MZ optical waveguides with higher transmittance, PBW was applied to poly-dimethyl-siloxane (PDMS) with higher transparency than PMMA. Thirty-micrometer thick PDMS films formed on silicon wafers were irradiated at different beam fluences using a 750-keV proton microbeam which reaches the half depth of the entire film thickness. The single mode propagation of the fabricated optical waveguide was checked by the 1.55-m light. The observation results showed that the single-mode propagation was detected only for the waveguide fabricated with the fluence of 100 nC/mm and that the propagated light intensity was higher than that of PMMA. The waveguide structure has been successfully fabricated in thin PDMS films by PBW.