  Two paramount challenges in carbon nanotube research are achieving
chirality-controlled synthesis and understanding chirality-dependent device
physics. High-throughput and in-situ chirality and electronic structural
characterization of individual carbon nanotubes is crucial for addressing these
challenges. Optical imaging and spectroscopy has unparalleled throughput and
specificity, but its realization for single nanotubes on substrates or in
devices has long been an outstanding challenge. Here we demonstrate video-rate
imaging and in-situ spectroscopy of individual carbon nanotubes on various
substrates and in functional devices using a novel high-contrast
polarization-based optical microscopy. Our technique enables the complete
chirality profiling of hundreds of as-grown carbon nanotubes. In addition, we
in-situ monitor nanotube electronic structure in active field-effect devices,
and observe that high-order nanotube optical resonances are dramatically
broadened by electrostatic doping. This unexpected behaviour points to strong
interband electron-electron scattering processes that can dominate ultrafast
dynamics of excited states in carbon nanotubes.
