Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

Consolino, Luigi; Campa, Annamaria; Ravaro, M.; Mazzotti, D.; Vitiello, Miriam S.; Bartalini, S.; Natale, P. De

doi:10.1063/1.4905872

Cited by 18 publications

(14 citation statements)

References 17 publications

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“…Doppler-free spectroscopy using a THz QCL was first shown in ref. [134], where saturation effects could be detected using a 2.5-THz device emitting in the mW power range, even though the Lamb dip lineshape was not recorded due to radiation feedback onto the QCL. This limitation was recently overcome by Wienold and co-workers [135], proving QCL-based Doppler-free spectroscopy for the first time.…”

Section: Metrological Grade Thz Qclsmentioning

confidence: 99%

QCL-based frequency metrology from the mid-infrared to the THz range: a review

et al. 2018

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Quantum cascade lasers (QCLs) are becoming a key tool for plenty of applications, from the mid-infrared (mid-IR) to the THz range. Progress in related areas, such as the development of ultra-low-loss crystalline microresonators, optical frequency standards, and optical fiber networks for time and frequency dissemination, is paving the way for unprecedented applications in many fields. For most demanding applications, a thorough control of QCLs emission must be achieved. In the last few years, QCLs' unique spectral features have been unveiled, while multifrequency QCLs have been demonstrated. Ultra-narrow frequency linewidths are necessary for metrological applications, ranging from cold molecules interaction and ultra-high sensitivity spectroscopy to infrared/THz metrology. A review of the present status of research in this field is presented, with a view of perspectives and future applications.

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Section: Metrological Grade Thz Qclsmentioning

confidence: 99%

QCL-based frequency metrology from the mid-infrared to the THz range: a review

et al. 2018

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“…In fact, even with very good signal-to-noise ratios, the MHz-level linewidth of the acquired line profiles did not allow to achieve the nominal precision of the THz spectrometer (about 5 × 10 −11 ). Fortunately, the high output power provided by THz QCLs can enable sub-Doppler spectroscopic techniques based on non-linear saturation of molecular transition [21] in analogy to what happened in the past years with mid-IR QCLs [22].…”

Section: Introductionmentioning

confidence: 97%

High-Q resonant cavities for terahertz quantum cascade lasers

Campa¹,

Consolino²,

Ravaro³

et al. 2015

Opt. Express

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We report on the realization and characterization of two different designs for resonant THz cavities, based on wire-grid polarizers as input/output couplers, and injected by a continuous-wave quantum cascade laser (QCL) emitting at 2.55 THz. A comparison between the measured resonators parameters and the expected theoretical values is reported. With achieved quality factor Q ≈ 2.5 × 10(5), these cavities show resonant peaks as narrow as few MHz, comparable with the typical Doppler linewidth of THz molecular transitions and slightly broader than the free-running QCL emission spectrum. The effects of the optical feedback from one cavity to the QCL are examined by using the other cavity as a frequency reference.

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“…In this framework, THz molecular spectroscopy has a key role and high precision measurements on different molecular transitions have been reported in the lower part of the THz spectrum, e.g. at 0.29 THz [17], 0.62 THz [18], 1.1 THz [19], 2.5 THz [13,20,21] and 3.3 THz [22]. Recent technologies, such as Frequency-Comb-based Photo-mixers [8,23] and Quantum Cascade Lasers (QCLs) [13,21,22] have demonstrated their capability to perform metrological grade THz spectroscopic measurements.…”

Section: Introductionmentioning

confidence: 99%

Room-Temperature Continuous-Wave Frequency-Referenced Spectrometer up to 7.5 THz

et al. 2018

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The lack of coherent room-temperature sources in the whole terahertz spectral window (0.3-10 THz) has significantly hampered the growth of scientific and technological applications in this range. Among them, highprecision frequency measurements of molecular transitions play a central role but remain an open challenge. Here, room-temperature generation and detection of continuous-wave, broadly tunable, narrow-linewidth THz radiation are presented, and their application to high-resolution spectroscopy in the broad 1-7.5 THz spectral range is demonstrated. This result has been achieved by implementing a Cherenkov phase-matching scheme into a channel waveguide in a nonlinear crystal. This simple approach, entirely based on robust telecom technology, unprecedently merges in a single source an ultra-broad continuous wave spectral coverage and a state-of-the-art accuracy (∼ 10 −9 ) in molecular transition center determination.

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Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

Cited by 18 publications

References 17 publications

QCL-based frequency metrology from the mid-infrared to the THz range: a review

QCL-based frequency metrology from the mid-infrared to the THz range: a review

High-Q resonant cavities for terahertz quantum cascade lasers

Room-Temperature Continuous-Wave Frequency-Referenced Spectrometer up to 7.5 THz

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