Polymer microring resonators for biosensing applications by nanoimprint lithography

Nowadays there is a permanently growing demand and need for simple, low cost, user friendly and real-time monitoring devices in biosensing technologies. In this context our contribution aims to demonstrate a fast fabrication process of centimeter-scale polymer microring resonators by UV nanoimprint lithography. A negative photoresist (SU-2) patterned by photolithography acts as a master mold in the imprinting process flow. High quality devices were designed and fabricated using rib waveguides with 1 μm by 1 μm width and height quadratic geometry. A controllable thickness of the residual layer with values down to 200 nm was achieved by tuning the thickness of the initial layer before imprint and the pattern dimensions of the master mold. The microrings with 1μm gap in a racetrack configuration are targeted for operation in a single mode at visible wavelengths, where cheap light sources are available and water absorption is much lower than at infrared wavelengths.