Low cost fabrication of polymer based optical devices

We present a simple and low-cost fabrication method for polymer based micro-optical devices. The fabricated micro-optical elements include binary gratings, surface relief gratings and optical waveguide structures. For fabrication of these optical elements a maskless optical lithography setup is employed which includes an UV LED and a spatial light modulator to project the desired microstructure on the photoresist coated on silicon substrate. We have used a grayscale photoresist i.e. OrmoComp, for recording the microstructure pattern. For writing of waveguides, a piezo stage is employed to stitch single exposure patterns together to form an extended structure. For replication into polymer foil, i.e. PMMA, to prepare the waveguide cladding, a hot embossing system is utilized. The cladding is then filled with UV curable core material and doctor blading is applied. The final optical devices are characterized for refractive indices and propagation losses. The described method enables low cost fabrication of the optical devices for applications in illumination technology, sensing and optical interconnects.