Optical microstructures fabricated by femtosecond laser two-photon polymerization

We investigated the feasibility of two-photon absorption (TPA) photopolymerization of methyl methacrylate initiated by a bimolecular system composed of 7-diethylamino-3-(2'-benzimidazolyl) coumarin and diphenyliodonium hexafluorophosphate under the irradiation of a Ti:sapphire femtosecond laser. The TPA cross section of the photosensitizer proved to be about 30×10-50 cm4 s/photon for a laser wavelength of 800 nm and the sensitizer/coinitiator system had a 1.4×105 mJ cm-2 threshold for the photopolymerization of methyl methacrylate. Furthermore, this photopolymer system was demonstrated to fabricate several micro-optical components, such as a half-ellipsoid voxel, a waveguide, a coupler and a grating.