Micro and Nanoscale Optical Surface Replication

In this study, we will report recent progresses in fabrication of precision chalcogenide glass micro and metalenses using PDMS (polydimethylsiloxane) molds. First a microlens or metalens design is established using geometric optics software or RCWA/FDTD (rigorous coupled wave analysis and finite-difference time-domain) methods. Masters with optical structures are first fabricated using deep UV or two photon lithography on silicon wafer and PDMS mold were replicated off silicon wafer and split into proper size (~3/4 inch for example). To construct chalcogenide sol precursor, As2S3 (arsenic sulfide) powder and propylamine (C3H9N) are mixed and placed or spin coated on (chalcogenide) glass substrate. Solvent and other small molecule additives are removed via low heat while the PDMS mold is pressed against the As2S3 sol using a non iso-thermal forming process. Surface measurements and optical testing will demonstrate that the replicated optical surface structures have high tolerances with desired optical performance. Characterizations using instruments such as Raman spectroscopy and XRD (X-ray diffraction) will further confirm material properties of the molded optics. Optical performance of these structures was evaluated using standard optical setup. Results in this research demonstrate a high volume, high precision and cost-effective micro and nano optical fabrication process.