Broadband stimulated Raman hyperspectral imaging of cells and semiconductors with synchronized fiber and solid-state sources
Shun Takahashi, Kento Kamei, Kenichi Oguchi, Kazuhiro Kuruma, Spencer J. Spratt, Hikaru Akaboshi, Yusuke Wakamoto, Takuya Maeda, Yasuyuki Ozeki
Abstract
We demonstrate broadband hyperspectral stimulated Raman scattering (SRS) microscopy covering over 2000 cm −1 , which is achieved by two tunable Stokes light sources synchronized with a pump light source. Specifically, a fiber optical parametric oscillator and a fiber laser, both equipped with automatic wavelength tuning capabilities, are employed to acquire SRS signals in the ranges of 270–2040 cm −1 and 2800–3100 cm −1 , respectively. Using this system, we perform hyperspectral SRS imaging of live HeLa cells, covering the entire fingerprint and C–H stretching regions. Furthermore, the spectral coverage in the lower fingerprint region (<1000 cm −1 ) enables SRS signal acquisition of wide bandgap semiconductors. We succeed in obtaining the SRS spectra of 4H-silicon carbide (SiC) and gallium nitride and demonstrate SRS imaging of the longitudinal optical phonon-plasmon coupled mode of 4H-SiC. We anticipate that the present method will further expand the applications of SRS in various scientific fields.