Critical setup parameter for ultrafast whitelight coherent antistokes raman scattering spectroscopy of living plankton in sea water

Abstract

The health and growth rates of shellfish depends critically on the precise chemical and biological makeup of the surrounding seawater. Rapid and continuous sensing of the marine environment enables improved harvests and better profits. However, underwater spectroscopy is still in its infancy. Our research aim is to develop a new sensor that is well-suited for marine environments and one that is capable of working at depths of up to 20 metres. We discuss a modified high intensity femtosecond coherent anti-Stokes Raman Scattering (CARS) system, which removes the usual limitations such as a limited wavenumber range and a low signal-to-noise ratio (SNR) due to non-resonant background. A particular set of Probe and Stokes pulses aim to investigate the spectra of various living plankton in seawater. It also determines critical parameters for the underwater CARS system such as signal dependent on the pulse energies, vibrational dephasing times and numerical aperture dependencies in forward CARS. This links to theory and greatly expands the understanding of CARS parameters for future underwater CARS experiments.