Femtosecond-Laser-Pulse Characterization and Optimization for CARS Microscopy

PLoS One. 2016 May 25;11(5):e0156371. doi: 10.1371/journal.pone.0156371. eCollection 2016.

Abstract

We present a simple method and its experimental implementation to determine the pulse durations and linear chirps of the pump-and-probe pulse and the Stokes pulse in a coherent anti-Stokes Raman scattering microscope at sample level without additional autocorrelators. Our approach exploits the delay line, ubiquitous in such microscopes, to perform a convolution of the pump-and-probe and Stokes pulses as a function of their relative delay and it is based on the detection of the photons emitted from an appropriate non-linear sample. The analysis of the non-resonant four-wave-mixing and sum-frequency-generation signals allows for the direct retrieval of the pulse duration on the sample and the linear chirp of each pulse. This knowledge is crucial in maximizing the spectral-resolution and contrast in CARS imaging.

MeSH terms

  • Equipment Design
  • Image Enhancement / methods
  • Lasers
  • Microscopy / methods*
  • Spectrum Analysis, Raman / methods*

Grants and funding

This research was supported exclusively by internal funds of Istituto Italiano di Tecnologia.