title: Multimode interference devices for focusing in microfluidic channels.
abstract: Low-cost, compact, automated optical microsystems for chemical analysis, such as microflow cytometers for identification of individual biological cells, require monolithically integrated microlenses for focusing in microfluidic channels, to enable high-resolution scattering and fluorescence measurements. The multimode interference device (MMI), which makes use of self-imaging in multimode waveguides, is shown to be a simple and effective alternative to the microlens for microflow cytometry. The MMIs have been designed, realized, and integrated with microfluidic channels in a silica-based glass waveguide material system. Focal spot sizes of 2.4 μm for MMIs have been measured at foci as far as 43.7 μm into the microfluidic channel.
authors.affiliation: Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Hamish C
authors.initials: HC
authors.lastname: Hunt
authors.forename: James S
authors.initials: JS
authors.lastname: Wilkinson
mesh_terms: D004867:Equipment Design; D005434:Flow Cytometry / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D055620:Optical Phenomena