Hurricane: A simplified optical resonator for optical-power-based sensing with nano-particle taggants

A simplified reflection-mode optical resonator for high-sensitivity biodetection is presented. Sensing is based on interaction between the optical micro-resonator and a nano-particle taggant attached to the analyte molecule, which causes scattering between resonator modes and a resultant change in broadband output power. The design of the resonator eliminates the need for evanescent coupling between the resonator cavity and bus waveguides, relying instead on direct core coupling, thus simplifying the device fabrication process and facilitating low-cost manufacture. Performance of the resonator sensor has been simulated via Finite Difference Time Domain (FDTD) calculations. Prototype resonator devices have been fabricated and characterized using an Atomic Force Microscope (AFM) probe to simulate a nano-particle; these experiments demonstrate the feasibility of detection using a low-cost broadband optical source and detector. Sensor subsystems incorporating the resonator chip, aminosilane surface functionalization, and microfluidic flow channels have been used to detect gold nano-particles suspended in a buffer solution; these experiments demonstrate the potential of detecting the occurrence of fewer than three particles attached to the active region of the micro-resonator.