A 2.7 $\mu$m Backward Wave Optical Parametric Oscillator Source for CO$_2$ Spectroscopy

TL;DR

This paper presents a narrowband backward wave optical parametric oscillator at 2.7 μm for CO₂ and H₂O spectroscopy, demonstrating stable, tunable mid-infrared output suitable for atmospheric sensing applications.

Contribution

It introduces a novel BWOPO source with direct mid-infrared output, characterized for the first time with new linewidth and stability measurement methods, eliminating the need for spectral stabilization.

Findings

Achieved 43 pm linewidth and 65 MHz stability limit without active stabilization.

Generated 2.3 μJ pulses at 2712 nm with temperature tuning of -1.77 GHz/K.

Demonstrated potential for robust DIAL atmospheric sensing systems.

Abstract

In this study, we demonstrated the direct use of an inherently narrowband backward wave in the mid-infrared for CO$_2$ and H$_2$O vapor spectroscopy in ambient air. This wave is generated in a backward wave optical parametric oscillator (BWOPO) pumped by a multi longitudinal mode laser at 1030 nm, eliminating the need for additional spectral narrowing or wavelength stabilization. A full characterization of the source is presented, revealing a central output at 2712 nm, showcasing temperature tuning of -1.77 GHz/K, and achieving an output pulse energy of 2.3 $\mu$J. Novel methods are introduced for measuring the linewidth and wavelength stability using lab air. These approaches demonstrate a narrow output of 43 pm and establish an upper limit of stability at 65 MHz, with no active means of stabilization. These findings underscore the potential of BWOPOs as a robust platform for future DIAL systems.