Abstract:
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High-sensitivity photodetection is at the heart of many optoelectronic applications, including spectroscopy, imaging, surveillance,
remote sensing and medical diagnostics. Achieving the highest possible sensitivity for a given photodetector technology requires the
development of ultra-small-footprint detectors, as the noise sources scale with the area of the detector. This must be accomplished
while sacrificing neither the optically active area of the detector nor its responsivity. Currently, such designs are based on
diffraction-limited approaches using optical lenses. Here, we employ a plasmonic flat-lens bull’s eye structure (BES) to
concentrate and focus light into a nanoscale colloidal quantum dot (CQD) photodetector. The plasmonic lenses function as
nanofocusing resonant structures that simultaneously offer color selectivity and enhanced sensitivity. Herein, we demonstrate the
first CQD photodetector with a nanoscale footprint, the optically active area of which is determined by the BES; this detector represents
an exciting opportunity for high-sensitivity sensing. |