Three-dimensional microfluidic liquid-core/liquid-cladding waveguide

This letter describes a three-dimensional liquid-core/liquid-cladding optical waveguide system. The core fluid was focused in the vertical direction by a transverse secondary flow (produced by a Dean vortex) and focused in the horizontal direction by two parallel sheath flows. The waveguide introduced less optical loss between the core fluid and the channel wall. Diffusion between the core fluid and the cladding fluid was reduced by high fluid velocities. The present system can be considered as a graded-index waveguide due to the diffusion effect. The width of the core fluid was manipulated by adjusting the sheath flow rates. Numerical simulations were conducted to support and interpret the experimental results. (C) 2010 American Institute of Physics. [doi:10.1063/1.3460279]