Mesoscopic particles with resonant and anti-resonant optical properties in microjluidics

One of the major pitfalls of multi liquid phase optofluidics is that it is difficult to adjust and tune the physical properties of the liquids that flow through these systems, on the fly. In this work, we demonstrate a viable solution through the use of a single mode polymeric waveguide integrated with dielectrophoretically controlled mesoparticles. We show a promising way of achieving fluidic property tuning of liquid optical waveguides and present the interaction between these well-controlled mesoparticles and light propagating in the polymeric waveguide. By packing and dispersing these particles near a single mode waveguiding core, homogenous media of desired refractive indices are formed. Changing the particle packing density allows this hybrid optofluidic waveguiding system to switch between the fundamental mode, when the refractive index of the media does not exceed that of the core to the first and second order modes. We attribute the modal transitions due to the formation of very specific packed particles conditions induced by dielectrophoresis, which have resonant and anti-resonant properties with respect to the light propagating in the single mode waveguide. These unique interactions can be used as a means for developing this device into an optofluidic sensor with high sensitivity and selectivity.