All-fiber multimodal CARS microscopy of live cells

Coherent anti-Stokes Raman scattering (CARS) microscopy is a promising tool for live cell imaging and has been applied to the study of diseases such as multiple sclerosis, atherosclerosis and hepatitis. Combining PCFs with optimally chirped fs pulses, high performance multimodal (i.e. simultaneous two-photon fluorescence (TPF), second harmonic generation (SHG) and CARS) imaging of live cells and tissues is possible using only a single laser. Here the paper demonstrates a fully operational multimodal live cell and tissue imaging system based on a compact fs Er fiber oscillator system. A key component is a newly developed ultra-highly nonlinear silica fiber (UHNLF) which greatly reduces the peak power requirement for Stokes pulse generation. A commercial fully integrated frequency doubled fs Er fiber laser (IMRA F100) was the pump for TPF and SHG imaging. Here, in this paper a multimodal image of a fixed rabbit atherosclerotic arterial sample where TPF (elastin), SHG (collagen) and CARS (lipid) signals were collected simultaneously. This demonstrates for the first time the feasibility of a compact all-fiber source for multimodal CARS microscopy of live cells and tissue.