Publication | Open Access
Mid-Infrared Frequency Comb Fourier Transform Spectrometer
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2010
Year
EngineeringAbsorption SpectroscopyMid-infrared Laser TechnologyChemistryOptical Frequency-comb-based-high-resolution SpectrometersSpectrochemical AnalysisOptical DiagnosticsInfrared OpticInstrumentationMolecular SpectroscopyBiophysicsInfrared TechnologyInfrared SpectroscopyFrequency CombsTrace Gas DetectionInfrared SensorSpectroscopyMass SpectrometryMolecular FingerprintingMedicineSpectroscopic Method
Optical frequency‑comb‑based high‑resolution spectrometers hold great promise for spectroscopy, yet the lack of suitable mid‑infrared comb sources has limited molecular fingerprinting. The study introduces the first mid‑infrared frequency‑comb Fourier transform spectrometer covering 2100–3700 cm⁻¹, enabling rapid, simultaneous broadband absorption spectra at up to 0.0056 cm⁻¹ resolution. The instrument couples a frequency‑comb source with Fourier transform detection to acquire broadband spectra across the mid‑infrared region with high resolution. It achieves part‑per‑billion detection limits in 30 s for methane, ethane, isoprene, and nitrous oxide, allowing precise concentration measurements in complex gas mixtures and real‑time trace‑gas detection for atmospheric science and medical diagnostics.
Optical frequency-comb-based-high-resolution spectrometers offer enormous potential for spectroscopic applications. Although various implementations have been demonstrated, the lack of suitable mid-infrared comb sources has impeded explorations of molecular fingerprinting. Here we present for the first time a frequency-comb Fourier transform spectrometer operating in the 2100-to-3700-cm-1 spectral region that allows fast and simultaneous acquisitions of broadband absorption spectra with up to 0.0056 cm-1 resolution. We demonstrate part-per-billion detection limits in 30 seconds of integration time for various important molecules including methane, ethane, isoprene, and nitrous oxide. Our system enables precise concentration measurements even in gas mixtures that exhibit continuous absorption bands, and it allows detection of molecules at levels below the noise floor via simultaneous analysis of multiple spectral features. This system represents a near real-time, high-resolution, high-bandwidth mid-infrared spectrometer which is ready to replace traditional Fourier transform spectrometers for many applications in trace gas detection, atmospheric science, and medical diagnostics.