1. Single Molecule Raman Detection with a Composite Microresonator and Metal Nanocavity System Xudong Fan (University of Missouri – Columbia) WGM field profile LCORR Laser light Sample Resonant surface plasmons Target analyte Ag nanoclusters Raman signal Concept: Raman signal is enhanced multiplicatively by both metal nanoclusters and a ring resonator. Based on this, a liquid Raman laser with an ultralow threshold can be achieved. LCORR: Liquid Core Optical Ring Resonator

2. Experimental Setup Fiber taper or waveguide sample 785 nm laser photodetector To spectrometer LCORR Fiber probe 200  m LCORR Fiber taper Radiative scattering (A)(B)

3. Raman laser Gain medium: carbon disulfide Excitation: 785 nm We have achieved Raman laser in carbon disulfide is flowed through the LCORR. Our next step will be to add silver nanoclusters to enhance the Raman scattering. The lasing threshold is expected to much lower.