Ultraviolet spectroscopy is crucial for exploring electronic and rovibronic transitions in atoms and molecules, serving a wide range of scientific pursuits, from verifying fundamental physical principles to supporting atmospheric chemistry and astrophysics. Leveraging high-resolution linear-absorption dual-comb spectroscopy within the ultraviolet spectrum, the MPQ team, under Nathalie Picque's guidance, has effectively overcome the challenges associated with low-light experiments. This development paves the path for innovative applications across numerous scientific and technological domains.
Predominantly applied in infrared absorption studies of small gas-phase molecules, dual-comb spectroscopy analyzes the interference between two laser frequency combs with slightly varying repetition frequencies. This approach, unhindered by the geometric constraints typical of traditional spectrometers, is renowned for its precision and accuracy. The MPQ researchers have now demonstrated that dual-comb spectroscopy can operate effectively in conditions characterized by significantly reduced light levels, using a photon-level interferometer that captures photon counting statistics with optimal signal-to-noise ratios.
This endeavor tackled the complexities involved in generating ultraviolet frequency combs and establishing dual-comb interferometers capable of maintaining long coherence times. By finely tuning the mutual coherence between two comb lasers, each emitting one femtowatt per comb line, the team achieved an exceptional build-up of interference signal statistics over periods extending beyond an hour. Bingxin Xu, the postdoctoral scientist who spearheaded these experiments, emphasized the technique's breakthrough in low-light interferometry, which is instrumental for extending dual-comb spectroscopy to shorter wavelengths.
Anticipating the future, this research holds the promise of facilitating dual-comb spectroscopy at short wavelengths, which could revolutionize precision vacuum- and extreme-ultraviolet molecular spectroscopy across broad spectral spans. Until now, such endeavors have been hampered by resolution and accuracy limitations, reliant on specialized equipment available only at dedicated facilities.
Nathalie Picque highlights the significance of their findings, suggesting that ultraviolet dual-comb spectroscopy, once a formidable challenge, is now within reach. This advancement not only extends dual-comb spectroscopy's full capabilities to low-light settings but also unlocks potential applications in areas such as precision spectroscopy, biomedical sensing, and environmental atmospheric monitoring.
Research Report:Near-ultraviolet photon-counting dual-comb spectroscopy
Related Links
Max Planck Institute of Quantum Optics
Understanding Time and Space
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