Lithographically defined intersecting optical waveguides and fluidic channels

Many optofluidic devices rely on interfacing optical waveguides with microfluidic channels. Often it can be difficult to realize micron scale waveguides and fluidic channels that are 100 times larger on the same platform. Further, it is often desirable for an optical waveguide intersection to occur at the vertical centre of a fluidic channel rather than at its top or at its bottom where the fluid is effectively stationary. We present a platform for optofluidics which can achieve straightforward integration of large scale fluidic channels and micron scale waveguides in the epoxy material SU8. A soft imprinting technique is used to define the optical waveguides as a thin inverted rib core layer between two thick cladding layers. The core is doped with Rhodamine dye to increase the refractive index and render it optically active for potential use as a lasing material. The fluidic channels are then formed by a single exposure through the core and both claddings.