Optofluidic ring resonator switch for optical particle transport.

In this work, we demonstrate an optofluidic switch using a microring resonator architecture to direct particles trapped in the evanescent field of a solid-core waveguide. When excited at the resonant wavelength, light inserted into the bus waveguide becomes amplified within the ring structure. The resulting high optical intensities in the evanescent field of the ring generate a gradient force that diverts particles trapped on the bus to the ring portion of the device. We show that this increase in optical energy translates to an increase of 250% in the radiation pressure induced steady-state velocity of particles trapped on the ring. We also characterize the switching fraction of the device, showing that 80% of particles are diverted onto the ring when the device is at an on-resonance state. The optofluidic switch we present here demonstrates the versatility in exploiting planar optical devices for integrated particle manipulation applications.