Spectroscopic Applications of Terahertz Quantum-Cascade Lasers
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| Title: | Spectroscopic Applications of Terahertz Quantum-Cascade Lasers |
|---|---|
| Description: | Quantum cascade lasers (QCLs) are attractive for high-resolution spectroscopy because they can provide high power and a narrow linewidth. They are particularly promising in the terahertz (THz) range since they can be used as local oscillators for heterodyne detection as well as transmitters for direct detection. However, THz QCL-based technologies are still under development and are limited by the lack of frequency tunability as well as the frequency and output power stability for free-running operation. In this dissertation, frequency tuning and linewidth of THz QCLs are studied in detail by using rotational spectroscopic features of molecular species. In molecular spectroscopy, the Doppler eff ect broadens the spectral lines of molecules in the gas phase at thermal equilibrium. Saturated absorption spectroscopy has been performed that allows for sub-Doppler resolution of the spectral features. One possible application is QCL frequency stabilization based on the Lamb dip. Since the tunability of the emission frequency is an essential requirement to use THz QCL for high-resolution spectroscopy, a new method has been developed that relies on near-infrared (NIR) optical excitation of the QCL rear-facet. A wide tuning range has been achieved by using this approach. The scheme is straightforward to implement, and the approach can be readily applied to a large class of THz QCLs. The frequency and output stability of the local oscillator has a direct impact on the performance and consistency of the heterodyne spectroscopy. A technique has been developed for a simultaneous stabilization of the frequency and output power by taking advantage of the frequency and power regulation by NIR excitation. The results presented in this thesis will enable the routine use of THz QCLs for spectroscopic applications in the near future. |
| Authors: | Alam, Tasmim |
| Resource Type: | eBook. |
| Subjects: | Spectroscope, Lasers, Terahertz spectroscopy |
| Categories: | SCIENCE / Spectroscopy & Spectrum Analysis |
| Database: | eBook Collection (EBSCOhost) |
| FullText | Links: – Type: ebook-pdf Text: Availability: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Spectroscopic Applications of Terahertz Quantum-Cascade Lasers – Name: Abstract Label: Description Group: Ab Data: Quantum cascade lasers (QCLs) are attractive for high-resolution spectroscopy because they can provide high power and a narrow linewidth. They are particularly promising in the terahertz (THz) range since they can be used as local oscillators for heterodyne detection as well as transmitters for direct detection. However, THz QCL-based technologies are still under development and are limited by the lack of frequency tunability as well as the frequency and output power stability for free-running operation. In this dissertation, frequency tuning and linewidth of THz QCLs are studied in detail by using rotational spectroscopic features of molecular species. In molecular spectroscopy, the Doppler eff ect broadens the spectral lines of molecules in the gas phase at thermal equilibrium. Saturated absorption spectroscopy has been performed that allows for sub-Doppler resolution of the spectral features. One possible application is QCL frequency stabilization based on the Lamb dip. Since the tunability of the emission frequency is an essential requirement to use THz QCL for high-resolution spectroscopy, a new method has been developed that relies on near-infrared (NIR) optical excitation of the QCL rear-facet. A wide tuning range has been achieved by using this approach. The scheme is straightforward to implement, and the approach can be readily applied to a large class of THz QCLs. The frequency and output stability of the local oscillator has a direct impact on the performance and consistency of the heterodyne spectroscopy. A technique has been developed for a simultaneous stabilization of the frequency and output power by taking advantage of the frequency and power regulation by NIR excitation. The results presented in this thesis will enable the routine use of THz QCLs for spectroscopic applications in the near future. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Alam%2C+Tasmim%22">Alam, Tasmim</searchLink> – Name: TypePub Label: Resource Type Group: TypPub Data: eBook. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Spectroscope%22">Spectroscope</searchLink><br /><searchLink fieldCode="DE" term="%22Lasers%22">Lasers</searchLink><br /><searchLink fieldCode="DE" term="%22Terahertz+spectroscopy%22">Terahertz spectroscopy</searchLink> – Name: SubjectBISAC Label: Categories Group: Su Data: <searchLink fieldCode="ZK" term="%22SCIENCE+%2F+Spectroscopy+%26+Spectrum+Analysis%22">SCIENCE / Spectroscopy & Spectrum Analysis</searchLink> |
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| RecordInfo | BibRecord: BibEntity: Classifications: – Code: 535.8 Scheme: ddc Type: prePub Languages: – Code: eng Text: English Subjects: – SubjectFull: Spectroscope Type: general – SubjectFull: Lasers Type: general – SubjectFull: Terahertz spectroscopy Type: general Titles: – TitleFull: Spectroscopic Applications of Terahertz Quantum-Cascade Lasers Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Alam, Tasmim – PersonEntity: Name: NameFull: Alam, Tasmim IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 01 Type: published Y: 2020 – D: 07 M: 09 Type: profile Y: 2022 Identifiers: – Type: isbn-print Value: 9783736972971 – Type: isbn-electronic Value: 9783736962972 Titles: – TitleFull: Spectroscopic Applications of Terahertz Quantum-Cascade Lasers Type: main |
| ResultId | 1 |
