THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing

Consolino, Luigi; Bartalini, S.; Beere, Harvey E.; Ritchie, D. A.; Vitiello, Miriam S.; Natale, P. De

doi:10.3390/s130303331

Cited by 55 publications

(42 citation statements)

References 31 publications

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“…THz QCLs have recently demonstrated good performances in high-resolution molecular spectroscopy [81–85]. Many gases have absorption strengths that are of the same order of magnitude as those observed in the mid-IR spectral range and three to six orders of magnitude stronger than those measured in the microwave region.…”

Section: Terahertz Qepasmentioning

confidence: 99%

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Patimisco

Scamarcio

Tittel

et al. 2014

Sensors

362

286

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A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

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Section: Terahertz Qepasmentioning

confidence: 99%

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Patimisco

Scamarcio

Tittel

et al. 2014

Sensors

362

286

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“…The ability to operate terahertz frequency quantum cascade lasers 1 (THz QCLs) in continuous-wave (CW) is essential for many applications, including their use in local oscillator systems, 2 spectroscopy/trace-gas detection, [3][4][5][6] and direct bolometric imaging. 7 It is also often important to ensure that the lasers have low dissipated power.…”

mentioning

confidence: 99%

Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

Isac

et al. 2014

Appl. Phys. Lett.

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We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20-25 mW at 15 K and maximum operating temperatures of 80-85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally singlemode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons. V C 2014 AIP Publishing LLC.

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“…in the field of THz metrology. Indeed, they combine an inherently high spectral purity (with intrinsic linewidths as low as 100 Hz [13,14]) with mW-level output powers, a mix that makes them ideal candidates for high-resolution and high-sensitivity spectroscopy [15] as well as for local oscillators in astronomical THz spectrometers [16]. Another recent achievement has been the extension to the THz region of optical frequency comb synthesizers [17][18][19], enabling direct and broadband phase/frequency referencing for any THz source and providing a new tool for high-precision measurements of THz frequencies.…”

Section: Introductionmentioning

confidence: 99%

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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THz QCL-Based Cryogen-Free Spectrometer for in Situ Trace Gas Sensing

Cited by 55 publications

References 31 publications

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

High-Q resonant cavities for terahertz quantum cascade lasers

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