Abstract
To fully exploit the power of coherent Raman imaging, techniques are needed to image more than one vibrational frequency simultaneously. We describe a method for switching between two vibrational frequencies based on a single fiber‐laser source.
Stokes pulses were generated by soliton self‐frequency shifting in a photonic crystal fiber. Pump and Stokes pulses were stretched to enhance vibrational resolution by spectral focusing. Stokes pulses were switched between two wavelengths on the millisecond time scale by a liquid‐crystal retarder. Proof‐of‐principle is demonstrated by coherent anti‐Stokes Raman imaging of polystyrene beads embedded in a poly(methyl methacrylate) (PMMA) matrix. The Stokes shift was switched between 3,050 cm−1, where polystyrene has a Raman transition, and 2,950 cm−1, where both polystyrene and PMMA have Raman resonances. The method can be extended to multiple vibrational modes.
Description
This is the peer reviewed version of the following article: Rentchler EC, Xie R, Hui R, JohnsonCK. Two-frequency CARS imaging by switching fiber laser excitation. Microsc Res Tech. 2018;81:413–418. https://doi.org/10.
1002/jemt.22993, which has been published in final form at https://doi.org/10.1002/jemt.22993. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.