Integrated Photonic Sensors

In 2017, this project began development of generalized PIC sensors in which silicon nitride (Si3N4) waveguides and waveguide-derived structures such as ring resonators probe the surrounding analyte via the evanescent field of the propagating TE (transverse electric) mode. The utilization of Si3N4 provides a lower refractive index contrast, therefore providing (i) tolerable evanescent exposure factor (Γ = 0.10) even in TE mode, and (ii) a reduction in the backscattering amplitude resulting from waveguide line-edge roughness. These structures are ideal choices since their fabrication is analogous to Datacom PICs, and they can undergo heterogeneous integration with III-V active SOA gain media without the need for on-chip polarization rotators. We also initiated development of grating couplers fabricated in silicon, for probing molecules in solution beyond the useful range of the evanescent field. Work in 2018 will expand on these efforts, provide an opportunity for corporate partners (IBM, OCD, OndaVia, Lockheed) to test devices directly in their product areas of interest, increase capability via spectrometer integration, and develop essential packaging solutions.