Photonic crystal slab and waveguide design for biological detection

In this work we have designed, fabricated, and tested a photonic crystal slab (PCS) with a line defect waveguide for the detection and identification of pathogenic DNA. A PCS is constructed by fabricating a material with 2-dimensional dielectric periodicity sandwiched between two semi-infinite cladding regions of lower effective index [1]. In order to uniquely identify pathogens critical to medical and homeland defense applications, the PCS was functionalized with a single stranded probe molecule providing highly specific binding for the target DNA. Integrated microfluidic channels provide delivery of the pathogen DNA resulting in hybridization and binding in the PCS holes. The binding event changes the refractive index of the PCS which results in a measurable change in the transmitted power. We will discuss design parameters and the suite of modeling tools used to optimize the PCS, defect waveguide, and coupling devices. An overview of the fabrication methods and tools will be provided and we will also report preliminary experimental results.