Related Experiment Video
Updated: Mar 2, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Mapping anomalous dispersion of air with ultrashort mid-infrared pulses
A V Mitrofanov1,2,3,4, A A Voronin1,2,5,6, D A Sidorov-Biryukov1,2,6
1Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 143025, Russia.
Abstract:
We present experimental studies of long-distance transmission of ultrashort mid-infrared laser pulses through atmospheric air, probing air dispersion in the 3.6-4.2-μm wavelength range. Atmospheric air is still highly transparent to electromagnetic radiation in this spectral region, making it interesting for long-distance signal transmission. However, unlike most of the high-transmission regions in gas media, the group-velocity dispersion, as we show in this work, is anomalous at these wavelengths due to the nearby asymmetric-stretch rovibrational band of atmospheric carbon dioxide. The spectrograms of ultrashort mid-infrared laser pulses transmitted over a distance of 60 m in our experiments provide a map of air dispersion in this wavelength range, revealing clear signatures of anomalous dispersion, with anomalous group delays as long as 1.8 ps detected across the bandwidth covered by 80-fs laser pulses.
Related Concept Videos
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
IR Frequency Region: X–H Stretching
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
IR Absorption Frequency: Delocalization
In IR...

