The Investigation of Subwavelength Grating Waveguides for Photonic Integrated Circuit Based Sensor Applications

Approaches to provide chip-scale aqueous chemical sensing for environmental and health monitoring via a photonic integrated circuit (PIC) technology are showing promise. To meet future U.S. Army demand, we have investigated waveguide structures compatible with feature sizes offered by modern mass-manufacturing PIC foundries. We have found that wide subwavelength grating (SWG) waveguide structures can maximally interact with an encapsulating analyte capture material with low propagation loss. We describe the analyte/light interaction component of our general integrated photonics chemical detector sensitivity model and use it to compare the effectiveness of waveguide geometries for sensing. The structures we have investigated afford superior detection to strip and slot waveguides. Finally, we introduce a novel tapered SWG waveguide geometry with improved transmission and similar sensitivity to nontapered SWG designs.