1
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Han C, Qu F, Wang X, Zhai X, Li J, Yu K, Zhao Y. Terahertz Spectroscopy and Imaging Techniques for Herbal Medicinal Plants Detection: A Comprehensive Review. Crit Rev Anal Chem 2023:1-15. [PMID: 36856792 DOI: 10.1080/10408347.2023.2183077] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Herbal medicine (HM), derived from various therapeutic plants, has garnered considerable attention for its remarkable effectiveness in treating diseases. However, numerous issues including improved varieties selection, hazardous residue detection, and concoction management affect herb quality throughout the manufacturing process. Therefore, a practical, rapid, nondestructive detection technology is necessary. Terahertz (THz) spectroscopy, with low energy, penetration, and fingerprint features, becomes preferable method for herb quality appraisal. There are three parts in our review. THz techniques, data processing, and modeling methods were introduced in Part I. Three primary applications (authenticity, composition and active ingredients, and origin detection) of THz in medicinal plants quality detection in industrial processing and marketing were detailed in Part II. A thorough investigation and outlook on the well-known applications and advancements of this field were presented in Part III. This review aims to bring new enlightenment to the in-depth THz application research in herbal medicinal plants.
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Affiliation(s)
- Chaoyue Han
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Fangfang Qu
- College of Mechanical and Electrical Engineering, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350000, China
| | - Xiaohui Wang
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xuedong Zhai
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Junmeng Li
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Keqiang Yu
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
- Key Laboratory of Agricultural Internet of Things, Ministry of Agriculture and Rural Affairs, Yangling, Shaanxi 712100, China
- Shaanxi Key Laboratory of Agricultural Information Perception and Intelligent Service, Yangling, Shaanxi 712100, China
| | - Yanru Zhao
- College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China
- Key Laboratory of Agricultural Internet of Things, Ministry of Agriculture and Rural Affairs, Yangling, Shaanxi 712100, China
- Shaanxi Key Laboratory of Agricultural Information Perception and Intelligent Service, Yangling, Shaanxi 712100, China
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2
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Direct Observation of Terahertz Frequency Comb Generation in Difference-Frequency Quantum Cascade Lasers. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11041416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Terahertz quantum cascade laser sources based on intra-cavity difference frequency generation from mid-IR devices are an important asset for applications in rotational molecular spectroscopy and sensing, being the only electrically pumped device able to operate in the 0.6–6 THz range without the need of bulky and expensive liquid helium cooling. Here we present comb operation obtained by intra-cavity mixing of a distributed feedback laser at λ = 6.5 μm and a Fabry–Pérot device at around λ = 6.9 μm. The resulting ultra-broadband THz emission extends from 1.8 to 3.3 THz, with a total output power of 8 μW at 78 K. The THz emission has been characterized by multi-heterodyne detection with a primary frequency standard referenced THz comb, obtained by optical rectification of near infrared pulses. The down-converted beatnotes, simultaneously acquired, confirm an equally spaced THz emission down to 1 MHz accuracy. In the future, this setup can be used for Fourier transform based evaluation of the phase relation among the emitted THz modes, paving the way to room-temperature, compact, and field-deployable metrological grade THz frequency combs.
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3
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Santamaria L, Di Sarno V, Aiello R, De Rosa M, Ricciardi I, De Natale P, Maddaloni P. Infrared Comb Spectroscopy of Buffer-Gas-Cooled Molecules: Toward Absolute Frequency Metrology of Cold Acetylene. Int J Mol Sci 2020; 22:E250. [PMID: 33383699 PMCID: PMC7795711 DOI: 10.3390/ijms22010250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/18/2020] [Accepted: 12/24/2020] [Indexed: 11/20/2022] Open
Abstract
We review the recent developments in precision ro-vibrational spectroscopy of buffer-gas-cooled neutral molecules, obtained using infrared frequency combs either as direct probe sources or as ultra-accurate optical rulers. In particular, we show how coherent broadband spectroscopy of complex molecules especially benefits from drastic simplification of the spectra brought about by cooling of internal temperatures. Moreover, cooling the translational motion allows longer light-molecule interaction times and hence reduced transit-time broadening effects, crucial for high-precision spectroscopy on simple molecules. In this respect, we report on the progress of absolute frequency metrology experiments with buffer-gas-cooled molecules, focusing on the advanced technologies that led to record measurements with acetylene. Finally, we briefly discuss the prospects for further improving the ultimate accuracy of the spectroscopic frequency measurement.
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Affiliation(s)
- Luigi Santamaria
- Agenzia Spaziale Italiana, Contrada Terlecchia, 75100 Matera, Italy;
| | - Valentina Di Sarno
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, Italy; (V.D.S.); (R.A.); (M.D.R.); (I.R.)
- Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Roberto Aiello
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, Italy; (V.D.S.); (R.A.); (M.D.R.); (I.R.)
- Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Maurizio De Rosa
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, Italy; (V.D.S.); (R.A.); (M.D.R.); (I.R.)
- Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Iolanda Ricciardi
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, Italy; (V.D.S.); (R.A.); (M.D.R.); (I.R.)
- Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy
| | - Paolo De Natale
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, Italy;
- Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Pasquale Maddaloni
- Consiglio Nazionale delle Ricerche-Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, Italy; (V.D.S.); (R.A.); (M.D.R.); (I.R.)
- Istituto Nazionale di Fisica Nucleare, Sez. di Napoli, Complesso Universitario di M.S. Angelo, Via Cintia, 80126 Napoli, Italy
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4
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Mezzapesa F, Garrasi K, Schmidt J, Salemi L, Pistore V, Li L, Davies AG, Linfield EH, Riesch M, Jirauschek C, Carey T, Torrisi F, Ferrari AC, Vitiello MS. Terahertz Frequency Combs Exploiting an On-Chip, Solution-Processed, Graphene-Quantum Cascade Laser Coupled-Cavity. ACS PHOTONICS 2020; 7:3489-3498. [PMID: 33365362 PMCID: PMC7747868 DOI: 10.1021/acsphotonics.0c01523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Indexed: 05/04/2023]
Abstract
The ability to engineer quantum-cascade-lasers (QCLs) with ultrabroad gain spectra, and with a full compensation of the group velocity dispersion, at terahertz (THz) frequencies, is key for devising monolithic and miniaturized optical frequency-comb-synthesizers (FCSs) in the far-infrared. In THz QCLs four-wave mixing, driven by intrinsic third-order susceptibility of the intersubband gain medium, self-locks the optical modes in phase, allowing stable comb operation, albeit over a restricted dynamic range (∼20% of the laser operational range). Here, we engineer miniaturized THz FCSs, comprising a heterogeneous THz QCL, integrated with a tightly coupled, on-chip, solution-processed, graphene saturable-absorber reflector that preserves phase-coherence between lasing modes, even when four-wave mixing no longer provides dispersion compensation. This enables a high-power (8 mW) FCS with over 90 optical modes, through 55% of the laser operational range. We also achieve stable injection-locking, paving the way to a number of key applications, including high-precision tunable broadband-spectroscopy and quantum-metrology.
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Affiliation(s)
- Francesco
P. Mezzapesa
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Katia Garrasi
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Johannes Schmidt
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Luca Salemi
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Valentino Pistore
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
| | - Lianhe Li
- School
of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, U.K.
| | - A. Giles Davies
- School
of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, U.K.
| | - Edmund H. Linfield
- School
of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, U.K.
| | - Michael Riesch
- Department
of Electrical and Computer Engineering, Technical University of Munich, Arcisstrasse 21, 80333 Munich, DE, Germany
| | - Christian Jirauschek
- Department
of Electrical and Computer Engineering, Technical University of Munich, Arcisstrasse 21, 80333 Munich, DE, Germany
| | - Tian Carey
- Cambridge
Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, U.K.
| | - Felice Torrisi
- Cambridge
Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, U.K.
| | - Andrea C. Ferrari
- Cambridge
Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, U.K.
| | - Miriam S. Vitiello
- NEST,
CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127, Pisa, Italy
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5
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Dunn A, Poyser C, Dean P, Demić A, Valavanis A, Indjin D, Salih M, Kundu I, Li L, Akimov A, Davies AG, Linfield E, Cunningham J, Kent A. High-speed modulation of a terahertz quantum cascade laser by coherent acoustic phonon pulses. Nat Commun 2020; 11:835. [PMID: 32047146 PMCID: PMC7012870 DOI: 10.1038/s41467-020-14662-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 01/23/2020] [Indexed: 11/28/2022] Open
Abstract
The fast modulation of lasers is a fundamental requirement for applications in optical communications, high-resolution spectroscopy and metrology. In the terahertz-frequency range, the quantum-cascade laser (QCL) is a high-power source with the potential for high-frequency modulation. However, conventional electronic modulation is limited fundamentally by parasitic device impedance, and so alternative physical processes must be exploited to modulate the QCL gain on ultrafast timescales. Here, we demonstrate an alternative mechanism to modulate the emission from a QCL device, whereby optically-generated acoustic phonon pulses are used to perturb the QCL bandstructure, enabling fast amplitude modulation that can be controlled using the QCL drive current or strain pulse amplitude, to a maximum modulation depth of 6% in our experiment. We show that this modulation can be explained using perturbation theory analysis. While the modulation rise-time was limited to ~800 ps by our measurement system, theoretical considerations suggest considerably faster modulation could be possible. The typical electronic modulation of terahertz quantum cascade lasers is fundamentally limited at fast timescales by device properties. Here the authors propose and study an alternative, acoustic mechanism for modulating such THz QCLs at high speed.
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Affiliation(s)
- Aniela Dunn
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
| | - Caroline Poyser
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Paul Dean
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Aleksandar Demić
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Alexander Valavanis
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Dragan Indjin
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Mohammed Salih
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Iman Kundu
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Lianhe Li
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Andrey Akimov
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Alexander Giles Davies
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Edmund Linfield
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - John Cunningham
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Anthony Kent
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
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6
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Alam T, Wienold M, Lü X, Biermann K, Schrottke L, Grahn HT, Hübers HW. Frequency and power stabilization of a terahertz quantum-cascade laser using near-infrared optical excitation. OPTICS EXPRESS 2019; 27:36846-36854. [PMID: 31873456 DOI: 10.1364/oe.27.036846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
We demonstrate a technique to simultaneously stabilize the frequency and output power of a terahertz quantum-cascade laser (QCL). This technique exploits frequency and power variations upon near-infrared illumination of the QCL with a diode laser. It does not require an external terahertz optical modulator. By locking the frequency to a molecular absorption line, we obtain a long-term (one-hour) linewidth of 260 kHz (full width at half maximum) and a root-mean-square power stability below 0.03%. With respect to the free-running case, this stabilization scheme improves the frequency stability by nearly two orders of magnitude and the power stability by a factor of three.
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7
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Li H, Yan M, Wan W, Zhou T, Zhou K, Li Z, Cao J, Yu Q, Zhang K, Li M, Nan J, He B, Zeng H. Graphene-Coupled Terahertz Semiconductor Lasers for Enhanced Passive Frequency Comb Operation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1900460. [PMID: 31637156 PMCID: PMC6794721 DOI: 10.1002/advs.201900460] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 07/20/2019] [Indexed: 05/20/2023]
Abstract
Optical frequency combs, consisting of well-controlled equidistant frequency lines, have been widely used in precision spectroscopy and metrology. Terahertz combs have been realized in quantum cascade lasers (QCLs) by employing either an active mode-locking or phase seeding technique, or a dispersion compensator mirror. However, it remains a challenge to achieve the passive comb formation in terahertz semiconductor lasers due to the insufficient nonlinearities of conventional saturable absorbers. Here, a passive terahertz frequency comb is demonstrated by coupling a multilayer graphene sample into a QCL compound cavity. The terahertz modes are self-stabilized with intermode beat note linewidths down to a record of 700 Hz and the comb operation of graphene-coupled QCLs is validated by on-chip dual-comb measurements. Furthermore, the optical pulse emitted from the graphene-coupled QCL is directly measured employing a terahertz pump-probe technique. The enhanced passive frequency comb operation is attributed to the saturable absorption behavior of the graphene-integrated saturable absorber mirror, as well as the dispersion compensation introduced by the graphene sample. The results provide a conceptually different graphene-based approach for passive comb formation in terahertz QCLs, opening up intriguing opportunities for fast and high-precision terahertz spectroscopy and nonlinear photonics.
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Affiliation(s)
- Hua Li
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Ming Yan
- State Key Laboratory of Precision SpectroscopyEast China Normal UniversityShanghai200062China
| | - Wenjian Wan
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
| | - Tao Zhou
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
| | - Kang Zhou
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Ziping Li
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Juncheng Cao
- Key Laboratory of Terahertz Solid State TechnologyShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Qiang Yu
- i‐LabSuzhou Institute of Nano‐Tech and Nano‐BionicsChinese Academy of Sciences398 Ruoshui RoadJiangsu215123SuzhouChina
| | - Kai Zhang
- i‐LabSuzhou Institute of Nano‐Tech and Nano‐BionicsChinese Academy of Sciences398 Ruoshui RoadJiangsu215123SuzhouChina
| | - Min Li
- School of Optical Electrical and Computer EngineeringUniversity of Shanghai for Science and TechnologyShanghai200093China
| | - Junyi Nan
- State Key Laboratory of Precision SpectroscopyEast China Normal UniversityShanghai200062China
| | - Boqu He
- State Key Laboratory of Precision SpectroscopyEast China Normal UniversityShanghai200062China
| | - Heping Zeng
- State Key Laboratory of Precision SpectroscopyEast China Normal UniversityShanghai200062China
- School of Optical Electrical and Computer EngineeringUniversity of Shanghai for Science and TechnologyShanghai200093China
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8
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Consolino L, Nafa M, Cappelli F, Garrasi K, Mezzapesa FP, Li L, Davies AG, Linfield EH, Vitiello MS, De Natale P, Bartalini S. Fully phase-stabilized quantum cascade laser frequency comb. Nat Commun 2019; 10:2938. [PMID: 31270325 PMCID: PMC6610094 DOI: 10.1038/s41467-019-10913-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 06/07/2019] [Indexed: 11/09/2022] Open
Abstract
Miniaturized frequency comb sources across hard-to-access spectral regions, i.e. mid- and far-infrared, have long been sought. Four-wave-mixing based Quantum Cascade Laser combs (QCL-combs) are ideal candidates, in this respect, due to the unique possibility to tailor their spectral emission by proper nanoscale design of the quantum wells. We demonstrate full-phase-stabilization of a QCL-comb against the primary frequency standard, proving independent and simultaneous control of the two comb degrees of freedom (modes spacing and frequency offset) at a metrological level. Each emitted mode exhibits a sub-Hz relative frequency stability, while a correlation analysis on the modal phases confirms the high degree of coherence in the device emission, over different power-cycles and over different days. The achievement of fully controlled, phase-stabilized QCL-comb emitters proves that this technology is mature for metrological-grade uses, as well as for an increasing number of scientific and technological applications.
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Affiliation(s)
- Luigi Consolino
- CNR-Istituto Nazionale di Ottica and LENS, Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy.
| | - Malik Nafa
- CNR-Istituto Nazionale di Ottica and LENS, Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Francesco Cappelli
- CNR-Istituto Nazionale di Ottica and LENS, Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Katia Garrasi
- NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza S. Silvestro 12, 56127, Pisa, Italy
| | - Francesco P Mezzapesa
- NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza S. Silvestro 12, 56127, Pisa, Italy
| | - Lianhe Li
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - A Giles Davies
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Edmund H Linfield
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Miriam S Vitiello
- NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza S. Silvestro 12, 56127, Pisa, Italy
| | - Paolo De Natale
- CNR-Istituto Nazionale di Ottica and LENS, Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Saverio Bartalini
- CNR-Istituto Nazionale di Ottica and LENS, Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
- ppqSense Srl, Via Gattinella 20, 50013, Campi Bisenzio, FI, Italy
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9
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Liehl A, Sulzer P, Fehrenbacher D, Rybka T, Seletskiy DV, Leitenstorfer A. Deterministic Nonlinear Transformations of Phase Noise in Quantum-Limited Frequency Combs. PHYSICAL REVIEW LETTERS 2019; 122:203902. [PMID: 31172766 DOI: 10.1103/physrevlett.122.203902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Indexed: 06/09/2023]
Abstract
Optical phase noise of femtosecond lasers is analyzed over various steps of broadband nonlinear frequency conversion. The intrinsic phase jitter of our system originates from quantum statistics in the mode-locked oscillator. Supercontinuum generation by four-wave-mixing processes preserves a noise minimum at the optical carrier frequency. From there, a quadratic increase of the comb linewidth results with mutually anticorrelated phase fluctuations of both spectral wings. Passive phase locking by difference frequency generation strongly enhances the optical phase noise to a level equaling the carrier-envelope phase jitter of the fundamental comb. The same value results from quadratic extrapolation of the optical phase noise to radio frequencies. Our findings are consistent with a fully deterministic transformation of phase noise according to the elastic tape model.
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Affiliation(s)
- A Liehl
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - P Sulzer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - D Fehrenbacher
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - T Rybka
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
| | - D V Seletskiy
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
- Department of Engineering Physics, Polytechnique Montréal, Montréal, H3T 1J4, Canada
| | - A Leitenstorfer
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany
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10
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Morohashi I, Katayama I, Kirigaya M, Irimajiri Y, Sekine N, Hosako I. High precision frequency measurement of terahertz waves using optical combs from a Mach-Zehnder-modulator-based flat comb generator. OPTICS LETTERS 2019; 44:487-490. [PMID: 30702660 DOI: 10.1364/ol.44.000487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 12/12/2018] [Indexed: 06/09/2023]
Abstract
Using a frequency-tunable optical comb generated from a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) and a nonlinear optical fiber, we demonstrated a frequency measurement of continuous terahertz wave sources with the frequency of 0.1 and 0.6 THz by an electro-optic sampling method. We clearly observed beat signals between the terahertz source and the optical two-tone extracted from the optical comb, allowing us to determine the absolute frequency. Owing to the wide comb spacing of the MZ-FCG, this method has a high potential for the high-speed measurement of the frequency of terahertz wave sources.
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11
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Waveguided Approach for Difference Frequency Generation of Broadly-Tunable Continuous-Wave Terahertz Radiation. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8122374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The 1–10 terahertz (THz) spectral window is emerging as a key region for plenty of applications, requiring not yet available continuous-wave room-temperature THz spectrometers with high spectral purity and ultra-broad tunability. In this regard, the spectral features of stabilized telecom sources can actually be transferred to the THz range by difference frequency generation, considering that the width of the accessible THz spectrum generally scales with the area involved in the nonlinear interaction. For this reason, in this paper we extensively discuss the role of Lithium Niobate (LN) channel-waveguides in the experimental accomplishment of a room-temperature continuous wave (CW) spectrometer, with μW-range power levels and a spectral coverage of up to 7.5 THz. To this purpose, and looking for further improvements, a thought characterization of specially-designed LN waveguides is presented, whilst discussing its nonlinear efficiency and its unprecedented capability to handle high optical power (107 W/cm2), on the basis of a three-wave-mixing theoretical model.
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12
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Khudchenko A, Pavelev D, Vaks V, Baryshev A. Overview of Techniques for THz QCL phase-locking. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201819504003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Consolino L, Jung S, Campa A, De Regis M, Pal S, Kim JH, Fujita K, Ito A, Hitaka M, Bartalini S, De Natale P, Belkin MA, Vitiello MS. Spectral purity and tunability of terahertz quantum cascade laser sources based on intracavity difference-frequency generation. SCIENCE ADVANCES 2017; 3:e1603317. [PMID: 28879235 PMCID: PMC5580883 DOI: 10.1126/sciadv.1603317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 08/05/2017] [Indexed: 05/20/2023]
Abstract
Terahertz sources based on intracavity difference-frequency generation in mid-infrared quantum cascade lasers (THz DFG-QCLs) have recently emerged as the first monolithic electrically pumped semiconductor sources capable of operating at room temperature across the 1- to 6-THz range. Despite tremendous progress in power output, which now exceeds 1 mW in pulsed and 10 μW in continuous-wave regimes at room temperature, knowledge of the major figure of merits of these devices for high-precision spectroscopy, such as spectral purity and absolute frequency tunability, is still lacking. By exploiting a metrological grade system comprising a terahertz frequency comb synthesizer, we measure, for the first time, the free-running emission linewidth (LW), the tuning characteristics, and the absolute center frequency of individual emission lines of these sources with an uncertainty of 4 × 10-10. The unveiled emission LW (400 kHz at 1-ms integration time) indicates that DFG-QCLs are well suited to operate as local oscillators and to be used for a variety of metrological, spectroscopic, communication, and imaging applications that require narrow-LW THz sources.
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Affiliation(s)
- Luigi Consolino
- Consiglio Nazionale delle Ricerche (CNR)–Istituto Nazionale di Ottica and European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy
| | - Seungyong Jung
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Annamaria Campa
- Consiglio Nazionale delle Ricerche (CNR)–Istituto Nazionale di Ottica and European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy
| | - Michele De Regis
- Consiglio Nazionale delle Ricerche (CNR)–Istituto Nazionale di Ottica and European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy
| | - Shovon Pal
- National Enterprise for nanoScience and nanoTechnology (NEST), CNR–Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Jae Hyun Kim
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA
| | - Kazuue Fujita
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita-ku, Hamamatsu 434-8601, Japan
| | - Akio Ito
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita-ku, Hamamatsu 434-8601, Japan
| | - Masahiro Hitaka
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita-ku, Hamamatsu 434-8601, Japan
| | - Saverio Bartalini
- Consiglio Nazionale delle Ricerche (CNR)–Istituto Nazionale di Ottica and European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy
| | - Paolo De Natale
- Consiglio Nazionale delle Ricerche (CNR)–Istituto Nazionale di Ottica and European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino (Firenze), Italy
| | - Mikhail A. Belkin
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA
- Corresponding author. (M.A.B.); (M.S.V.)
| | - Miriam Serena Vitiello
- National Enterprise for nanoScience and nanoTechnology (NEST), CNR–Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
- Corresponding author. (M.A.B.); (M.S.V.)
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14
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Mapping of electromagnetic waves generated by free-running self-oscillating devices. Sci Rep 2017; 7:9203. [PMID: 28835623 PMCID: PMC5569046 DOI: 10.1038/s41598-017-09802-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/28/2017] [Indexed: 11/08/2022] Open
Abstract
Near-field mapping has proven to be a powerful technique for characterizing and diagnosing antennas in the microwave frequency range. However, conventional measurement methods based on a network analyzer cannot be applied to on-chip antenna devices extensively studied for future wireless communication in the millimeter wave (mm-wave) (30-300 GHz) and terahertz (THz) wave (0.1-10 THz) frequency regions. Here, we present a new asynchronous mapping technique to investigate the spatial distribution of not only the amplitude but also the phase of the electric field generated by free-running, self-oscillating generators including CMOS oscillators, Gunn oscillators, resonant tunneling diodes, and quantum cascaded lasers. Using a photonic-electronic hybrid measurement system, a wide frequency coverage, minimal invasiveness of the field to be measured, and phase distribution measurements with a theoretically-limited sensitivity are simultaneously achieved. As a proof-of-concept experiment, we demonstrate the mapping of a mm-wave (77 GHz) generated by a free-running Gunn oscillator and antenna characterization based on near-to-far field transformation.
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15
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Ashtiani F, Aflatouni F. Integrated electro-optical phase-locked loop for high resolution optical synthesis. OPTICS EXPRESS 2017; 25:16171-16181. [PMID: 28789125 DOI: 10.1364/oe.25.016171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
Electrical frequency synthesizers have been in existence for several decades and are an integral part of almost every communication and sensing system. In the optical domain, however, despite promising bench-top demonstration of frequency synthesizers, large size, high-power consumption, and high-cost have significantly limited their large deployment compared to their electrical counterparts. Here we report an integrated electro-optical phase locked loop (EOPLL) as the core of an optical synthesizer where photonic and electronic devices are integrated in a standard silicon-on-insulator (SOI) process. A sophisticated integrated electronic-photonic architecture is proposed enabling reliable, low-cost, and high resolution optical synthesis. The small on-chip optical delay and electronically assisted frequency detection and acquisition provide tunable phase and frequency locking. The integrated EOPLL consumes 28.5 mW with total chip area of 2.4 mm2 making it comparable with electrical synthesizers enabling large-scale deployment in applications such as low-cost optical spectroscopy, detection, sensing, and optical communication.
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16
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Qi X, Agnew G, Kundu I, Taimre T, Lim YL, Bertling K, Dean P, Grier A, Valavanis A, Linfield EH, Giles Davies A, Indjin D, Rakić AD. Multi-spectral terahertz sensing: proposal for a coupled-cavity quantum cascade laser based optical feedback interferometer. OPTICS EXPRESS 2017; 25:10153-10165. [PMID: 28468390 DOI: 10.1364/oe.25.010153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/20/2017] [Indexed: 06/07/2023]
Abstract
We propose a laser feedback interferometer operating at multiple terahertz (THz) frequency bands by using a pulsed coupled-cavity THz quantum cascade laser (QCL) under optical feedback. A theoretical model that contains multi-mode reduced rate equations and thermal equations is presented, which captures the interplay between electro-optical, thermal, and feedback effects. By using the self-heating effect in both active and passive cavities, self-mixing signal responses at three different THz frequency bands are predicted. A multi-spectral laser feedback interferometry system based on such a coupled-cavity THz QCL will permit ultra-high-speed sensing and spectroscopic applications including material identification.
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17
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Jackson M, Zink LR. Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies. J Vis Exp 2015:e53399. [PMID: 26709957 DOI: 10.3791/53399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is ± 5 parts in 10(7). Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH2F2, was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO2 pump laser, and strength.
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Affiliation(s)
- Michael Jackson
- Department of Physics, Central Washington University; College of Science and Technology, Millersville University;
| | - Lyndon R Zink
- Department of Physics, University of Wisconsin-La Crosse
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Vitiello MS, Scalari G, Williams B, De Natale P. Quantum cascade lasers: 20 years of challenges. OPTICS EXPRESS 2015; 23:5167-82. [PMID: 25836550 DOI: 10.1364/oe.23.005167] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We review the most recent technological and application advances of quantum cascade lasers, underlining the present milestones and future directions from the Mid-infrared to the Terahertz spectral range. Challenges and developments, which are the subject of the contributions to this focus issue, are also introduced.
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Bachmann D, Leder N, Rösch M, Scalari G, Beck M, Arthaber H, Faist J, Unterrainer K, Darmo J. Broadband terahertz amplification in a heterogeneous quantum cascade laser. OPTICS EXPRESS 2015; 23:3117-3125. [PMID: 25836170 DOI: 10.1364/oe.23.003117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate a broadband terahertz amplifier based on ultrafast gain switching in a quantum cascade laser. A heterogeneous active region is processed into a coupled cavity metal-metal waveguide device and provides broadband terahertz gain that allows achieving an amplification bandwidth of more than 500 GHz. The temporal and spectral evolution of a terahertz seed pulse, which is generated in an integrated emitter section, is presented and an amplification factor of 21 dB is reached. Furthermore, the quantum cascade amplifier emission spectrum of the emerging sub-nanosecond terahertz pulse train is measured by time-domain spectroscopy and reveals discrete modes between 2.14 and 2.68 THz.
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20
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Campa A, Consolino L, Ravaro M, Mazzotti D, Vitiello MS, Bartalini S, De Natale P. High-Q resonant cavities for terahertz quantum cascade lasers. OPTICS EXPRESS 2015; 23:3751-3761. [PMID: 25836227 DOI: 10.1364/oe.23.003751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
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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21
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Gambetta A, Cassinerio M, Coluccelli N, Fasci E, Castrillo A, Gianfrani L, Gatti D, Marangoni M, Laporta P, Galzerano G. Direct phase-locking of a 8.6-μm quantum cascade laser to a mid-IR optical frequency comb: application to precision spectroscopy of N2O. OPTICS LETTERS 2015; 40:304-307. [PMID: 25680033 DOI: 10.1364/ol.40.000304] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We developed a high-precision spectroscopic system at 8.6 μm based on direct heterodyne detection and phase-locking of a room-temperature quantum-cascade-laser against an harmonic, 250-MHz mid-IR frequency comb obtained by difference-frequency generation. The ∼30 dB signal-to-noise ratio of the detected beat-note together with the achieved closed-loop locking bandwidth of ∼500 kHz allows for a residual integrated phase noise of 0.78 rad (1 Hz-5 MHz), for an ultimate resolution of ∼21 kHz, limited by the measured linewidth of the mid-IR comb. The system was used to perform absolute measurement of line-center frequencies for the rotational components of the ν2 vibrational band of N2O, with a relative precision of 3×10(-10).
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Burghoff D, Yang Y, Hayton DJ, Gao JR, Reno JL, Hu Q. Evaluating the coherence and time-domain profile of quantum cascade laser frequency combs. OPTICS EXPRESS 2015; 23:1190-202. [PMID: 25835878 DOI: 10.1364/oe.23.001190] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Recently, much attention has been focused on the generation of optical frequency combs from quantum cascade lasers. We discuss how fast detectors can be used to demonstrate the mutual coherence of such combs, and present an inequality that can be used to quantitatively evaluate their performance. We discuss several technical issues related to shifted wave interference Fourier Transform spectroscopy (SWIFTS), and show how such measurements can be used to elucidate the time-domain properties of such combs, showing that they can possess signatures of both frequency-modulation and amplitude-modulation.
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23
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Galli I, Bartalini S, Cancio P, Cappelli F, Giusfredi G, Mazzotti D, Akikusa N, Yamanishi M, De Natale P. Mid-infrared frequency comb for broadband high precision and sensitivity molecular spectroscopy. OPTICS LETTERS 2014; 39:5050-3. [PMID: 25166071 DOI: 10.1364/ol.39.005050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a nonlinear downconversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase-locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multifrequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Perot cavity.
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24
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Haase C, Agner JA, Merkt F. High-resolution laser spectroscopy between 0.9 and 14.3 THz in a supersonic beam: Rydberg-Rydberg transitions of atomic Xe at intermediate n values. J Chem Phys 2013; 138:244202. [DOI: 10.1063/1.4809740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Nagano S, Ito H, Kumagai M, Kajita M, Hanado Y. Microwave synthesis from a continuous-wave terahertz oscillator using a photocarrier terahertz frequency comb. OPTICS LETTERS 2013; 38:2137-2139. [PMID: 23939002 DOI: 10.1364/ol.38.002137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report low-noise microwave synthesis from radiation with a frequency of 0.3 THz using a photocarrier frequency comb in a photoconductive antenna. The synthesized microwave signal at 1 GHz is phase coherent to the 0.3 THz radiation and has a fractional instability of 1×10(-15) within 300 s averaging times and single-sideband phase noise of -105 dB/Hz at a 100 Hz offset from the carrier. This terahertz (THz)-to-microwave synthesizer is capable of being a THz frequency divider, which would be indispensable to not only THz metrology but also future high-speed wireless networks.
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Affiliation(s)
- Shigeo Nagano
- National Institute of Information and Communications Technology, Koganei, Tokyo, Japan.
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26
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Mezzapesa FP, Columbo LL, Brambilla M, Dabbicco M, Borri S, Vitiello MS, Beere HE, Ritchie DA, Scamarcio G. Intrinsic stability of quantum cascade lasers against optical feedback. OPTICS EXPRESS 2013; 21:13748-13757. [PMID: 23736628 DOI: 10.1364/oe.21.013748] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We study the time dependence of the optical power emitted by terahertz and mid-IR quantum cascade lasers in presence of optical reinjection and demonstrate unprecedented continuous wave (CW) emission stability for strong feedback. We show that the absence of coherence collapse or other CW instabilities typical of diode lasers is inherently associated with the high value of the photon to carrier lifetime ratio and the negligible linewidth enhancement factor of quantum cascade lasers.
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27
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Consolino L, Bartalini S, Beere HE, Ritchie DA, Vitiello MS, De Natale P. THz QCL-based cryogen-free spectrometer for in situ trace gas sensing. SENSORS 2013; 13:3331-40. [PMID: 23478601 PMCID: PMC3658749 DOI: 10.3390/s130303331] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/02/2013] [Accepted: 03/08/2013] [Indexed: 11/22/2022]
Abstract
We report on a set of high-sensitivity terahertz spectroscopy experiments making use of QCLs to detect rotational molecular transitions in the far-infrared. We demonstrate that using a compact and transportable cryogen-free setup, based on a quantum cascade laser in a closed-cycle Stirling cryostat, and pyroelectric detectors, a considerable improvement in sensitivity can be obtained by implementing a wavelength modulation spectroscopy technique. Indeed, we show that the sensitivity of methanol vapour detection can be improved by a factor ≈ 4 with respect to standard direct absorption approaches, offering perspectives for high sensitivity detection of a number of chemical compounds across the far-infrared spectral range.
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Affiliation(s)
- Luigi Consolino
- CNR, Istituto Nazionale di Ottica and LENS (European Laboratory for Non-linear Spectroscopy), Via Carrara 1, Sesto Fiorentino (FI) 50019, Italy; E-Mails: (S.B.); (M.S.V.); (P.D.N.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +39-55-457-2227; Fax: +39-55-457-2451
| | - Saverio Bartalini
- CNR, Istituto Nazionale di Ottica and LENS (European Laboratory for Non-linear Spectroscopy), Via Carrara 1, Sesto Fiorentino (FI) 50019, Italy; E-Mails: (S.B.); (M.S.V.); (P.D.N.)
| | - Harvey E. Beere
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK; E-Mails: (H.E.B.); (D.A.R.)
| | - David A. Ritchie
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK; E-Mails: (H.E.B.); (D.A.R.)
| | - Miriam Serena Vitiello
- CNR, Istituto Nazionale di Ottica and LENS (European Laboratory for Non-linear Spectroscopy), Via Carrara 1, Sesto Fiorentino (FI) 50019, Italy; E-Mails: (S.B.); (M.S.V.); (P.D.N.)
- NEST, CNR, Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa 56127, Italy
| | - Paolo De Natale
- CNR, Istituto Nazionale di Ottica and LENS (European Laboratory for Non-linear Spectroscopy), Via Carrara 1, Sesto Fiorentino (FI) 50019, Italy; E-Mails: (S.B.); (M.S.V.); (P.D.N.)
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28
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Cancio P, Bartalini S, De Rosa M, Giusfredi G, Mazzotti D, Maddaloni P, Vitiello M, De Natale P. Atomic and molecular spectroscopy with optical-frequency-comb-referenced IR coherent sources. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20135702003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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