Direct laser writing of optical biosensor based on photonic Floquet topological insulator for protein detection

Photonic Floquet topological insulators (PFTI) allow scatter-free propagation of light along its edges. The PFTI of interest consists of helical waveguides arranged in a honeycomb lattice. When irradiated with an input beam on the edge of the PFTI, light propagates from one end of the waveguide-system to the other along the edges. The intensity and the final position of light is theoretically found to be dependent on the difference in the refractive indices of the core and cladding of the waveguides. For a system of helical-waveguides filled with a solvent, the effective refractive index of the system varies with the concentration of the analyte in the solvent and this can be measured by monitoring the position and intensity of the output-light. This paper discusses the design, principle, simulation and fabrication of such a PFTI based biosensor.