Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 38 for “"quantum cascade laser"”.
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Quantum Cascade Laser Frequency Combs
Quantum cascade lasers (QCLs) have been the dominant source of high-power infrared radiation ever since their invention in 1994. The ability to engineer their emission wavelengths from 3 𝜇m to 300 𝜇m has allowed scientists to use QCLs in a plethora of applications, ranging from spectroscopy to …
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The transistor-injected quantum cascade laser
Since its invention in 1994 the quantum cascade laser has become the most important coherent emission source for mid-infrared and terahertz ranges. The quantum cascade laser is a unipolar semiconductor laser that utilizes electron transitions between quantized states in the conduction band for …
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GaAs/AlGaAs mid-infrared quantum cascade laser
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
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GaAs/AlGaAs far-infrared quantum cascade laser
… pumped inter subband farinfrared (40-100[mu]m) laser, using GaAs/ AlxGal-xAs heterostructures. The proposed design aims to use LO-phonon-mediated depopulation of the lower THz laser level to aid the intersubband laser population inversion. Interband recombination occurs by means of stimulated …
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Terahertz imaging and quantum cascade laser based devices
… demonstrated using recently developed terahertz quantum-cascade laser (QCL) sources, along with commercial, focal plane array thermal detectors. The system uses a high power (48 mW) 4.3-THz QCL, which is also used to characterize the focal plane array, resulting in a noise equivalent power (NEP) …
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Electromagnetic modeling of terahertz quantum cascade laser waveguides and resonators
… and resonators used in terahertz (THz) quantum cascade lasers (QCLs) is presented. Simulations and analysis of two types were performed: two-dimensional waveguides, and two- and three-dimensional resonators. Both metal-metal and semi-insulating (SI) surface-plasmon geometries were …
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Quantum cascade laser-based mid-infrared spectroscopic imaging systems with polarization capabilities
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-08-01
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Epitaxial design, fabrication development, and characterization of transistor-injected quantum cascade laser structures
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01
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The design and fabrication of an inp-based transistor-injected quantum cascade laser
… practical solutions to these problems. While quantum cascade lasers (QCLs) present one appealing solution for these infrared sources, inherent limitations related to efficiency and operational control leave room for improvement. The transistor-injected quantum cascade laser (TI-QCL) presents a …
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Development of a quantum cascade laser based spectrometer for high-resolution spectroscopy of gas phase C60
This thesis research details the development of a quantum cascade laser (QCL) based continuous-wave cavity ringdown spectrometer (cw-CRDS) coupled to an oven supersonic expansion source. This is the first such work that uses a QCL in conjunction with the cw-CRD technique and a supersonic expansion …
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Discrete-frequency infrared imaging with a quantum cascade laser and diffuse optical Raman tomography: methods toward improving clinically relevant label-free chemical contrast
… with significant potential include the use of quantum cascade laser technology for mid-infrared spectral imaging and diffuse Raman tomography for three dimensional chemical analysis. In this thesis, we constructed and evaluated two analytical instruments which represent the first steps toward …
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Metal-insulator-insulator-metal plasmonic waveguides and devices
… polymer)-assisted MIM waveguides and terahertz quantum cascade laser MIM waveguides are numerically analyzed. The numerical analysis of finite planar MIM waveguides using the transfer matrix formalism reveals both bound and leaky SP modes: three lowest energy bound modes and the highest energy …
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Trace gas spectrometry using quantum cascade lasers
… absorption of light from a rapid frequency swept laser. A bench mounted two channel quantum cascade laser absorption spectrometer was used during experiments to observe and reduce nonlinear effects that arise from tuning the lasers during the absorption of light by several atmospherically …
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Exhaled breath analysis using laser absorption spectroscopy
… and therapeutic monitoring. For this thesis, laser spectroscopic techniques were employed to measure exhaled nitric oxide (NO), carbonyl sulfide (OCS) and carbon dioxide (CO2). A pulsed quantum cascade laser operating at 4.86 microns was coupled to a 36-m optical path length Herriott cell for …
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Towards terahertz dual-comb spectroscopy based on quantum cascade lasers
In this thesis, terahertz (THz) laser frequency combs are improved and THz dual-comb spectroscopy method is demonstrated. To achieve better performance of THz quantum cascade laser (QCL) frequency combs, several broadband homogeneous and heterogeneous gain media are characterized, and corresponding …
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Development of Broadband Semiconductor Laser Frequency Combs
Quantum Cascade Laser (QCL) is a compact, mature and flexible coherent radiation source in both terahertz (THz) and mid-infrared (midIR) frequency range. Many molecules have rotational-vibrational absorption bands in midIR, making QCL-based dual comb spectroscopy (DCS) systems the ideal tool for …
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Long-wave infrared frequency combs based on quantum cascade lasers
Ever since the invention of quantum cascade laser (QCL), the performance and the flexibility in design has made it a desirable source for a wide range of applications, such as trace-chemical sensing, health monitoring, frequency metrology, noninvasive imgaing and infrared countermeasures. The LWIR …
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The application of quantum cascade lasers to mid-infrared gas sensing
This thesis explains the development of a quantum cascade laser based gas sensor and the verification of performance of the resulting product. The capability to detect trace levels of multiple species in varying physical conditions, specifically high temperature is shown.Optical designs capable of …
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Development of terahertz quantum-cascade lasers
… remarkable development of mid-infrared ( ... ) quantum-cascade lasers (QCLs) in the past decade, this thesis describes the development of electrically-pumped terahertz quantum-cascade lasers in GaAs/AlsGal_.As heterostructures that span a spectral range of 1.59 - 5.0 THz ( ... ). A …
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Surface-emitting distributed feedback terahertz quantum-cascade phase-locked laser arrays
… THz emission from metal-metal waveguide quantum-cascade laser is proposed and implemented. Several surface-emitting distributed feedback terahertz lasers are coupled through the connection phase sectors between them. Through carefully choosing the length of phase sectors, each laser will …
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