Broadband complementary vibrational spectroscopy with cascaded intra-pulse difference frequency generation

TL;DR

This paper introduces a cascaded intra-pulse difference-frequency generation method to significantly expand the spectral bandwidth of complementary vibrational spectroscopy, enabling simultaneous IR and Raman measurements over a broader range.

Contribution

The work demonstrates a simple approach to extend the spectral coverage of CVS to over 2000 cm-1 using cascaded IDFG, doubling previous bandwidth limits.

Findings

Achieved broadband CVS spectra spanning over 2000 cm-1

Expanded spectral coverage beyond previous ~1000 cm-1 limit

Enabled simultaneous IR and Raman measurements over a broader range

Abstract

One of the essential goals of molecular spectroscopy is to measure all fundamental molecular vibrations simultaneously. To this end, one needs to measure broadband infrared (IR) absorption and Raman scattering spectra, which provide complementary vibrational information. A recently demonstrated technique called complementary vibrational spectroscopy (CVS) enables simultaneous measurements of IR and Raman spectra with a single device based on a single laser source. However, the spectral coverage was limited to ~1000 cm-1, which partially covers the spectral regions of the fundamental vibrations. In this work, we demonstrate a simple method to expand the spectral bandwidth of the CVS with a cascaded intra-pulse difference-frequency generation (IDFG). Using the system, we measure broadband CVS spectra of organic liquids spanning over 2000 cm-1, more than double the previous study.