Low-Cost Fabrication of Polymer Based Micro-Optical Devices for Application in Illumination, Sensing, and Optical Interconnects

Summary form only given. Fabrication of desired micro structures in polymers is always of keen interest for applications in illumination optics, sensors and optical interconnects. The challenge is to fabricate structures in the sub-micron range but at low cost. Among other fabrication methods as described in [1], maskless lithography tends to be cost effective and can create sub-micron structures. Here, we present a simple and low-cost fabrication process chain for fabricating desired micro structures in polymer, i.e. PMMA. The microstructures are, for example, grating structures and straight waveguides. The fabrication is done using a maskless lithography setup which employs a spatial light modulator and a UV LED. For recording the microstructure pattern a grayscale photoresist, i.e. OrmoComp, is used, which is coated on the silicon substrate. For writing waveguides, a translation stage is included in the setup to stitch the single exposure patterns together to form a continuous waveguide structure, as can be seen in Fig. 1(c). For replication an intermediate stamp, which is stable at high thermal loads, is obtained by casting Polydimethyl siloxane (PDMS) in an oven for 15 mins at 100 ° C. The stamp is then used to replicate the microstructures onto the Polymethyl methacrylate (PMMA) using a hot embossing system, i.e. Jenoptik HEX03. A 500 gm thick PMMA (Plexiglas XT99524, Thyssen Krupp) foil is placed on the PDMS (ELASTOSIL RT 607A/B) stamp and an embossing pressure of 7 kPa is applied for 4 mins. After cooling to a release temperature of 40 ° C, the PMMA foil is removed manually.