Porous Waveguide in the Kretschmann Configuration for Small Molecule Detection

In this work, we theoretically and experimentally demonstrate a highly sensitive porous silicon membrane waveguide biosensor in the Kretschmann configuration, and show how the cladding material directly impacts the waveguide sensor detection sensitivity and resonance width. Dielectric and metal-clad porous waveguides in the Kretchmann configuration have the potential to achieve significantly enhanced performance for small molecule detection compared to planar waveguide and surface plasmon resonance sensors due to increased surface area and strong field confinement in the porous waveguide layer. First order perturbation theory calculations predict that the quality factors of polymer-cladded porous silicon waveguides with porous silicon losses less than ~500 dB/cm are at least two times larger than the quality factors of gold-cladded porous silicon waveguides and traditional surface plasmon resonance sensors.