Particle counting based on high-order Fano resonance in an optofluidic microcavity

We demonstrate particle counting based on high-order Fano resonance (FR) in an optofluidic microcavity. The high-order FR excited by a thin fiber taper can penetrate the liquid core of a microcapillary. An optical pulse is generated due to the resonant spectrum shift when a particle crosses the microcavity. Analogous to other methods, such a pulse can be used for particle counting. The sampled particles of PS microspheres and super-absorbent polymer broken beads are used for particle-counting experiments. All results confirm the feasibility of such a counting method.