From fundamental physics to the clinic

Film-coupled nanocube cavities enhance the emission rate of embedded emitters more than a thousandfold while keeping the light bright and directional. This work identified the mechanisms behind the enhancement and showed that extreme Purcell enhancement need not come at the cost of brightness or directionality — the combination the group’s later single-photon sources depend on.

A single colloidal quantum dot in a nanogap cavity emits single photons at 1550 nm with a lifetime of tens of picoseconds — a spontaneous emission rate enhanced up to 10,000-fold, with blinking almost entirely suppressed — at room temperature and made entirely from solution-processed components.

Diamond is centrosymmetric and has no bulk second-order nonlinearity. Inside nanogap cavities, a diamond film only 12 nanometers thick becomes a bright source of second-harmonic light, enhanced more than ten-million-fold, while several nonlinear processes run in the same cavity at once — a nanoscale frequency converter in a material with no bulk second-order response.

Pyroelectric detectors are limited by how fast heat can move. By structuring the absorber as a metasurface only nanometers thick, we made a pyroelectric photodetector with sub-nanosecond response and built-in spectral selectivity — and have since pushed the same idea to gigahertz speeds.

Silver nanocube metasurfaces patterned into micrometer-scale pixels, with six resonances spanning the visible and near-infrared, can be combined into 9,261 colors — enough to reconstruct a photograph in absorption at 560 dpi. The bird above is 2 mm across and made entirely of nanoscale cavities.

An inkjet-printed immunoassay for the cardiac biomarker BNP, built directly inside nanogap cavities: antibodies on a nanometer-thin polymer brush over gold, capped with silver nanocubes. The cavity brightens the fluorescence more than a hundredfold and lowers the detection limit fourteen-fold. With Ashutosh Chilkoti’s group; supported by an NIH R01.