Tip‐enhanced broadband CARS spectroscopy and imaging using a photonic crystal fiber based broadband light source

Abstract

We report tip‐enhanced broadband coherent anti‐Stokes Raman scattering (CARS) spectroscopy and imaging based on a broadband light source using a photonic crystal fiber. Multiplexing from 900 cm–1 to 2200 cm–1 is achieved by optimizing the supercontinuum generation process at a high numerical aperture focus. By combining this system with a shear‐force microscope, semiconducting carbon nanotubes are imaged with a spatial resolution of 60 nm. Our results show that tip‐enhanced broadband CARS image exhibits a positive contrast even though the enhancement effect has not been fully optimized. Analyses of delay‐dependent tip‐enhanced broadband CARS spectra suggest the possibilities of multiple carrier interactions that uniquely occur at high intensities within the nanotubes. Copyright © 2012 John Wiley & Sons, Ltd.