Application of the inclined exposure and molding process to fabricate a micro beam-splitter with nanometer roughness

This paper successfully used inclined exposure technology to fabricate a wafer-level 3D micro cube beam splitter with a 45° optical grade surface (~1.4 mm thick). This research also tests the effect of solvent loss percentage of the SU-8 3035 polymer material (85.45 % solvent removal) to optimum surface roughness on the surface roughness of inclined surfaces. The smallest surface roughness achieved in the experiments using SU-8 3035 material with a thickness of 1.4 mm was less than 34 nm (400 × 400 μm area). And the reflective surface roughness of the molding cube beam-splitter is below 2 nm. The optical power of the fabricated cube beam splitter is about 60.55 and 39.44 % for transmission and reflection, respectively. This type of micro cube beam-splitter can be used as a key component in Pico-projectors, Interferometers, bio detection systems, data storage systems, and linear encoder optic systems. And this novel technology also has the characteristics of high throughput and wafer-level assembly.