Pedestaled subwavelength grating metamaterial waveguide for sensitivity enhancement (Conference Presentation)

Silicon photonics has been studied intensively for biosensing applications due to the potential of leveraging the matured fabrication process to integrate thousands of sensors on a single chip and massively produce sensing chips at an affordable cost. However, the high index contrast of silicon does not only enable ultra-compact sensors, but also limits the interaction between optical field and analytes. To enhance the sensitivity, silicon subwavelength grating metamaterial (SGM) microring resonator was proposed to improve the interaction between photons and analytes and has demonstrated significant sensitivity improvement. Due to the asymmetric index profile along the vertical direction, further increasing the sensitivity becomes challenging. To reduce the asymmetricity, in this paper, we propose pedestaled SGM which allows further increasing the interaction between optical field and analytes. We analyzed and demonstrated enhanced bulk sensitivity and limit of detection (LOD) in SGM microring resonators with pedestal structure. To compare the bulk sensitivity and LOD of regular SGM microring resonator (Sample A) and pedestal SGM microring resonators, the devices with same structure design as Sample A were soaked in buffered oxide etch (BOE) for 30 seconds (Sample B) and 50 seconds (Sample C) to make pedestal shape. Real time monitoring of the resonance shift measurement shows the detection of streptavidin at a low concentration of 0.1 ng/mL for Sample C and a similar response for 1 ng/mL, 10 ng/mL, 100 ng/mL, 1 μg/mL, 10 μg/mL, and 100 μg/mL. Our results suggest that such pedestaled SGM microring resonators have great potential for specific biomarkers diagnosis.