Epi-detected hybrid coherent Raman micro-spectroscopy

Abstract

We demonstrate efficient epi-detected coherent Raman micro-spectroscopy using a simple laser system based on a femtosecond mode-locked oscillator. In our experiment, the non-resonant background is eliminated by using a hybrid technique, which combines laser pulse shaping and timing with frequency-resolved detection, and is based on the different temporal behavior of parametric and nonparametric processes. We perform careful analysis to make sure the coherent Raman-resonant signal is generated in the backward direction, and not forward-generated and then back-scattered. This demonstration may have important implications for coherent Raman microscopy.

Keywords:

• Raman spectroscopy
• CARS
• femtosecond lasers
• microscopy

Acknowledgments

This work was supported by Texas Advanced Research Program (Grant No. 010366-0001-2007), National Science Foundation (Grant Nos. PHY 354897 and 722800), the Office of Naval Research, the Army Research Office (Grant No. W911NF-07-1-0475), and the Robert A. Welch Foundation (Grant No. A1547).