Fs-laser-induced Fabrication of Polymeric Optical and Fluidic Microstructures

In this paper first experimental results are presented on the fabrication of integrated-optical microstructures by femtosecond-laser irradiation at the surface or in the volume of a polymeric substrate. Thereby the refractive index or the optical absorption coefficient of the polymer material is locally modified in a controllable way due to nonlinear optical effects like multi-photon absorption. By this way surface relief grating structures, volume grating structures and linear waveguiding structures are generated. The surface relief gratings have diffraction efficiencies about 0.2 (first diffraction order), the diffraction efficiencies of the volume gratings are approximately smaller by one order of magnitude. Besides experiments have been performed on the modification of the polymeric surface by fs-laser irradiation followed by subsequent development of the irradiated area by an etching liquid generating linear groove structures. By this way simple linear microstructures are generated into the polymer substrate. The results of these experiments are relevant for the fabrication of three-dimensional structures in the polymeric substrate in the future. All the gratings and the linear microstructures can be considered as basic components for the fabrication of complex micro-optical and fluidic systems in a polymeric substrate (photonic lab-on-the-chip).