Peter Randolph Hazard Stark

Emerging tools for real-time label-free detection of interactions on functional protein microarrays.

The availability of extensive genomic information and content has spawned an era of high‐throughput screening that is generating large sets of functional genomic data. In particular, the need to understand the biochemical wiring within a cell has introduced novel approaches to map the intricate networks of biological interactions arising from the interactions of proteins. The current technologies for assaying protein interactions – yeast two‐hybrid and immunoprecipitation with mass spectrometric detection – have met with considerable success. However, the parallel use of these approaches has identified only a small fraction of physiologically relevant interactions among proteins, neglecting all nonprotein interactions, such as with metabolites, lipids, DNA and small molecules. This highlights the need for further development of proteome scale technologies that enable the study of protein function. Here we discuss recent advances in high‐throughput technologies for displaying proteins on functional protein microarrays and the real‐time label‐free detection of interactions using probes of the local index of refraction, carbon nanotubes and nanowires, or microelectromechanical systems cantilevers. The combination of these technologies will facilitate the large‐scale study of protein interactions with proteins as well as with other biomolecules.

Integrated high quality factor lithium niobate microdisk resonators.

Lithium Niobate (LN) is an important nonlinear optical material. Here we demonstrate LN microdisk resonators that feature optical quality factor ~10(5), realized using robust and scalable fabrication techniques, that operate over a wide wavelength range spanning visible and near infrared. Using our resonators, and leveraging LNs large second order optical nonlinearity, we demonstrate on-chip second harmonic generation with a conversion efficiency of 0.109 W(-1).

Breaking the diffraction barrier outside of the optical near-field with bright, collimated light from nanometric apertures

The optical diffraction limit has been the dominant barrier to achieving higher optical resolution in the fields of microscopy, photolithography, and optical data storage. We present here an approach toward imaging below the diffraction barrier. Through the exposure of photosensitive films placed a finite and known distance away from nanoscale, zero-mode apertures in thin metallic films, we show convincing, physical evidence that the propagating component of light emerging from these apertures shows a very strong degree of collimation well past the maximum extent of the near-field (λ0/4n–λ0/2n). Up to at least 2.5 wavelengths away from the apertures, the transmitted light exhibits subdiffraction limit irradiance patterns. These unexpected results are not explained by standard diffraction theory or nanohole-based “beaming” rationalizations. This method overcomes the diffraction barrier and makes super-resolution fluorescence imaging practical.

Integrated lithium niobate nonlinear optical devices

We demonstrate robust and scalable fabrication of lithium niobate nanophotonic devices including microdisk and microring resonators. Our devices feature optical quality factors over 105 and are promising for nonlinear optical applications.