Fabrication of surface plasmon waveguides in CYTOP

Abstract

There is considerable interest in Long-Range Surface Plasmon-Polariton (LRSPP) waves, which inherently have a low attenuation, for sensing applications. LRSPPs propagating along thin metal stripes arranged as integrated optical structures, such as Mach-Zehnder interferometers (MZIs), are or particular interest for biosensing. In order for sensors to be functional, high-quality metal stripe waveguides integrated with microfluidic channels are required. Wafer-based fabrication processes have been developed and implemented to fabricate thin (35 nm) Au stripes and features embedded into CYTOP claddings, with etched microfluidic channels exposing sections of the stripes for sensing. CYTOP is a fluoropolymer having a refractive index close to that of water, motivating its use as a cladding material. The fabrication processes developed are discussed and measurements (physical and optical) on operating sensors are presented.