Tunable and compact dispersion compensation of broadband THz quantum cascade laser frequency combs

Mezzapesa, Francesco P.; Pistore, Valentino; Garrasi, Katia; Li, Lianhe; Davies, A. G.; Linfield, E. H.; Dhillon, Sukhdeep; Vitiello, Miriam S.

doi:10.1364/oe.27.020231

Cited by 35 publications

(58 citation statements)

References 20 publications

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“…THz QCLs have been shown both to emit ultrashort pulses via active mode locking [10,11] and/or RF switching techniques [12] and also to present wide spectral bandwidth coverage [13][14][15] in comb emission without pulses [16,17]. Comb operation can be controlled with dispersion compensation [7,18,19] and/or with efficient RF injection locking to metrological sources [20,21].…”

Section: Introductionmentioning

confidence: 99%

RF Injection of THz QCL Combs at 80 K Emitting over 700 GHz Spectral Bandwidth

et al. 2020

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We report about RF injection locking of an homogeneous THz quantum cascade laser operating at 3 THz central frequency. The extremely diagonal nature of the optical transition, combined with low-loss copper-based double-metal waveguides, allow CW operation up to 105 K and CW power in excess of 5.6 mW measured at 80 K. Terahertz emission spanning up to 600 GHz, together with a narrow beatnote, indicate comb operation at 80 K, and strong RF injection clearly modifies the laser spectrum up to 700 GHz spectral bandwidth making these devices ideal candidates for an on-chip dual comb spectrometer.

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Section: Introductionmentioning

confidence: 99%

RF Injection of THz QCL Combs at 80 K Emitting over 700 GHz Spectral Bandwidth

et al. 2020

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“…Francesco P. Mezzapesa 1 We also demonstrate a tunable scheme for lithographically independent compensation of the GDD over the majority of the laser operational range and spectral bandwidth, while achieving evenly spaced optical modes with similar intensities [4]. As most dispersion compensation techniques in the THz range are not tunable [1,[5][6], this limits the spectral coverage of the comb and the emitted output power, restricting potential applications in, for example, metrology and ultrashort THz pulse generation.…”

Section: Resultsmentioning

confidence: 99%

THz quantum cascade laser frequency combs

Mezzapesa

Garrasi

Pistore³

et al. 2019

2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)

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We demonstrate THz optical frequency comb (FC) operation based on ultra-broadband, record dynamic range Quantum Cascade Lasers (QCLs) which exploit a heterogeneous active region design to achieve low and flat chromatic dispersion at the center of the gain curve. By implementing a Gires-Tournois Interferometer (GTI), as tightly coupled at one end of the QCL cavity, we provide lithographically-independent control of the free-running coherence properties of such THz-QCL FC and attain wide dispersion compensation regions, where stable and narrow (~3 kHz linewidth) single beatnotes extend over an operation range that is significantly larger than that of dispersiondominated bare laser cavity counterparts.

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“…modes of the QCL device with temperature/current scans, that in our case is of few hundreds MHz, can be more than enough to perform high-accuracy acquisitions on selected molecular transitions, but might be a limitation in the analysis of complex gas mixtures. For these challenging applications, our spectrometer can in principle be equipped with an array of slightly frequency detuned THz QCLs, as well as broader dynamic range devices, such as dispersion compensated lasers 56 , or saturable-absorbers-equipped QCL-FCs. These devices can provide a broader spectral coverage and, at the same time, FC operation at higher driving currents, providing higher output power and broader frequency scans.…”

Section: Discussionmentioning

confidence: 99%

Quantum cascade laser based hybrid dual comb spectrometer

et al. 2020

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Four-wave-mixing-based quantum cascade laser frequency combs (QCL-FC) are a powerful photonic tool, driving a recent revolution in major molecular fingerprint regions, i.e. mid-and far-infrared domains. Their compact and frequency-agile design, together with their high optical power and spectral purity, promise to deliver an all-in-one source for the most challenging spectroscopic applications. Here, we demonstrate a metrological-grade hybrid dual comb spectrometer, combining the advantages of a THz QCL-FC with the accuracy and absolute frequency referencing provided by a free-standing, optically-rectified THz frequency comb. A proof-of-principle application to methanol molecular transitions is presented. The multi-heterodyne molecular spectra retrieved provide state-of-the-art results in line-center determination, achieving the same precision as currently available molecular databases. The devised setup provides a solid platform for a new generation of THz spectrometers, paving the way to more refined and sophisticated systems exploiting full phase control of QCL-FCs, or Doppler-free spectroscopic schemes.

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Tunable and compact dispersion compensation of broadband THz quantum cascade laser frequency combs

Cited by 35 publications

References 20 publications

RF Injection of THz QCL Combs at 80 K Emitting over 700 GHz Spectral Bandwidth

RF Injection of THz QCL Combs at 80 K Emitting over 700 GHz Spectral Bandwidth

THz quantum cascade laser frequency combs

Quantum cascade laser based hybrid dual comb spectrometer

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