Optimally shaped narrowband pulses for Femtosecond Stimulated Raman Spectroscopy in the range 330-750 nm

TL;DR

This paper presents a simple spectral filtering modification to enhance narrowband pulse generation via second harmonic generation for femtosecond stimulated Raman spectroscopy, improving spectral resolution, gain, and tunability.

Contribution

The authors introduce a spectral filtering technique that significantly improves the spectral and temporal qualities of narrowband pulses used in FSRS.

Findings

Increased Raman gain at a given pulse energy.

Enhanced spectral resolution of the pulses.

Extended tunable range from 330 to 750 nm.

Abstract

Spectral compression of femtosecond pulses by second harmonic generation in the presence of substantial group velocity dispersion provides a convenient source of narrowband Raman pump pulses for femtosecond stimulated Raman spectroscopy (FSRS). We discuss here a simple and efficient modification that dramatically increases the versatility of the second harmonic spectral compression technique. Adding a spectral filter following second harmonic generation produces narrowband pulses with a superior temporal profile. This simple modification i) increases the Raman gain for a given pulse energy, ii) improves the spectral resolution, iii) suppresses coherent oscillations associated with slowly dephasing vibrations, and iv) extends the useful tunable range to at least 330-750 nm.