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Frequency stable and low phase noise THz synthesis for precision spectroscopy
Léo Djevahirdjian1, Loïc Lechevallier2, Marie-Aline Martin-Drumel3
1Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble, France. leo.djevahirdjian@univ-grenoble-alpes.fr.
Nature Communications
|November 7, 2023
Summary
We developed a terahertz (THz) emission source with Hz-level linewidth and mHz/s stability, ideal for ultra-high resolution molecular physics. This tunable THz source operates from 0.1 to 1.4 THz, offering precise spectral analysis.
Area of Science:
- Physics
- Spectroscopy
- Quantum Optics
Background:
- Terahertz (THz) spectroscopy requires stable, narrow-linewidth sources for high-resolution molecular analysis.
- Existing THz sources often face limitations in tunability, phase noise, and spectral resolution.
Purpose of the Study:
- To present a robust method for generating continuously tunable, low phase noise THz emission.
- To demonstrate the source's capability for ultra-high resolution molecular spectroscopy.
Main Methods:
- Photomixing two commercial distributed feedback (DFB) lasers locked to a V-shaped optical cavity.
- Optical feedback stabilization for enhanced laser coherence.
- Absorption spectroscopy of methanol and water vapors up to 1.4 THz.
- Saturation spectroscopy for hyperfine structure analysis.
Main Results:
- Achieved continuously tunable THz emission from 0.1 to 1.4 THz.
- Demonstrated Hz-level linewidth and mHz/s frequency stability.
- Recorded low-pressure absorption lines of methanol and water vapors.
- Resolved hyperfine structure of a water line at 556.9 GHz with 10 kHz FWHM.
Conclusions:
- The developed THz source offers exceptional spectral performance and agility.
- This technology is well-suited for ultra-high resolution molecular physics applications.
- The source enables detailed investigation of molecular spectral features.
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