Proceedings Article | 15 March 2018
Proc. SPIE. 10506, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XV
KEYWORDS: Optical components, Visible radiation, Waveguides, Silicon, Life sciences, Flow cytometry, Photonics, Integrated optics, Integrated photonics, Diffraction gratings
For many applications in life sciences, the biologically relevant information is probed by means of visible light. Many of the critical optical components have, unfortunately, still a large footprint and heavy price tag. Silicon nitride integrated waveguide optics –allowing for complex routing schemes of visible light across a chip– assumes a promi-nent role in the progressing miniaturization of optical devices. However, in order to have the light in the chip interro-gate a distant biological entity, diffraction gratings have to be used to couple light out of the chip.
Ideally, all the light from a waveguide would be coupled out into a beam with a predefined polarization, phase, and intensity profile. As such they should be able to produce any functional beam that is typically prepared by free space optical components. For a standard, linear grating an exponential intensity decay is observed along the grating, i.e., more light is coupled out at the start than at the end.
Here, we present a specially designed metasurface that is able to deliver highly uniform illumination escaping the photonics chip in a collimated beam at a predesigned angle. Because of its integrated nature, a component like this is highly relevant for the miniaturization of, e.g., flow cytometry applications. We therefore include microfluidic chan-nels on top of the photonics chip and demonstrate the cytometric capabilities with fluorescent polystyrene beads. The opto-fluidic chips are processed in a CMOS pilot line. Our work demonstrates the potential of integrated visible pho-tonics and flat optics for life science applications.
