Rapid Infrared Spectroscopic Nanoimaging with nano-FTIR Holography

Scattering-type scanning near-field optical microscopy (s-SNOM) and its derivate, Fourier transform infrared nanospectroscopy (nano-FTIR), are emerging techniques for infrared (IR) nanoimaging and spectroscopy, with applications in diverse fields ranging from nanophotonics, chemical imaging, and materials science. However, spectroscopic nanoimaging is still challenged by the limited acquisition rate of current nano-FTIR technology. Here we combine s-SNOM, nano-FTIR, and synthetic optical holography (SOH) to achieve infrared spectroscopic nanoimaging at unprecedented speed (eight spectroscopically resolved images in 20 min), which we demonstrate with a polymer composite sample. Beyond being fast, our method promises to enable nanoimaging in the far IR spectral range, which is covered by IR supercontinuum and synchrotron sources, but not by current quantum cascade laser technology.