title: Fabrication of three-dimensional polymer quadratic nonlinear grating structures by layer-by-layer direct laser writing technique.
abstract: We demonstrate the fabrication of a three-dimensional (3D) polymer quadratic nonlinear (χ(2)) grating structure. By performing layer-by-layer direct laser writing (DLW) and spin-coating approaches, desired photobleached grating patterns were embedded in the guest-host dispersed-red-1/poly(methylmethacrylate) (DR1/PMMA) active layers of an active-passive alternative multilayer structure through photobleaching of DR1 molecules. Polyvinyl-alcohol and SU8 thin films were deposited between DR1/PMMA layers serving as a passive layer to separate DR1/PMMA active layers. After applying the corona electric field poling to the multilayer structure, nonbleached DR1 molecules in the active layers formed polar distribution, and a 3D χ(2) grating structure was obtained. The χ(2) grating structures at different DR1/PMMA nonlinear layers were mapped by laser scanning second harmonic (SH) microscopy, and no cross talk was observed between SH images obtained from neighboring nonlinear layers. The layer-by-layer DLW technique is favorable to fabricating hierarchical 3D polymer nonlinear structures for optoelectronic applications with flexible structural design.
authors.affiliation: Department of Physics, National Chung Cheng University, Ming Hsiung, Chiayi, Taiwan.
authors.forename: Danh Bich
authors.initials: DB
authors.lastname: Do
authors.forename: Jian Hung
authors.initials: JH
authors.lastname: Lin
authors.forename: Ngoc Diep
authors.initials: ND
authors.lastname: Lai
authors.forename: Hung-Chih
authors.initials: HC
authors.lastname: Kan
authors.forename: Chia Chen
authors.initials: CC
authors.lastname: Hsu