Correcting phase errors is key to building low cost, high performance integrated optical phased arrays for mass-market applications such as automotive lidar. In this work, we present a phase interrogator component for optical phased arrays which enables the phase error to be measured immediately before the output array of optical emitters. A 32-element silicon/silicon nitride optical phased array is realized in a dual layer photonics stack to verify the component performance. Silicon enables high density integration of photonic components and the phase interrogator has a compact design which fits between waveguides with a separation of 2.5 μm. The phase interrogators enable correction of the beam without any measurement or evaluation of the far-field.
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.
Fluorescence detection is a commonly used technique to detect particles. Microscopes are used for the fluorescence detection of the micro-particles. However, the conventional microscopes are bulky. It is cumbersome to integrate all the equipment used for detection in one setup. They can be replaced by photonic chips for the detection of micro-particles such as cells. Most of the biological detection techniques require the utilization of the visible range of the spectrum. SiN as a waveguide material stands out for biological applications due to its transparency in the visible spectrum. Specifically designed grating couplers can be exploited to focus from inside SiN waveguides at a designated location above the chip. Those SiN focusing grating couplers can mimic microscope objectives for on-chip biological detection applications such as fluorescence and Raman spectroscopy. In this report, we present a 2D SiN focusing grating coupler. We study the effect of the grating design on the focus properties of visible light using finite-difference time-domain simulations.
The detection and identification of nanoparticles has caught the attention in the last decade due to its potential
application on small bio-particles. Raman spectroscopy stands out as a label-free technique for the detection of such
particles. However, it may require a high concentration of particles. In a solution with low concentration of particles to
detect Raman spectroscopy, the number of particles in the detection area can be increased by optical trapping. The
optical trapping force applied to a dielectric nanoparticle is proportional to the gradient of the optical intensity field.
Plasmonic nanopores are efficient platforms for trapping nanoparticles due to highly enhanced localized field and its
high gradient. Here, we report our work on the optical trapping and assembly of 20 nm polystyrene nanoparticles in a
plasmonic nanopore and its detection by Raman spectroscopy.