Littérature scientifique sur le sujet « AlSb QCLs »

The extension of the available spectral range covered by quantum cascade lasers (QCL) would allow one to address new molecular spectroscopy applications, in particular in the long wavelength domain of the mid-infrared. We report in this paper the realization of distributed feedback (DFB) QCLs, made of InAs and AlSb, that demonstrated a continuous wave (CW) and a single mode emission at a wavelength of 17.7 µm, with output powers in the mW range. This is the longest wavelength for DFB QCLs, and for any QCLs or semiconductor lasers in general, operating in a CW at room temperature.

Abstract InAs/AlSb quantum cascade detectors (QCDs) grown strain-balanced on GaSb substrates are presented. This material system offers intrinsic performance-improving properties, like a low effective electron mass of the well material of 0.026 m 0, enhancing the optical transition strength, and a high conduction band offset of 2.28 eV, reducing the noise and allowing for high optical transition energies. InAs and AlSb strain balance each other on GaSb with an InAs:AlSb ratio of 0.96:1. To regain the freedom of a lattice-matched material system regarding the optimization of a QCD design, submonolayer InSb layers are introduced. With strain engineering, four different active regions between 3.65 and 5.5 µm were designed with InAs:AlSb thickness ratios of up to 2.8:1, and subsequently grown and characterized. This includes an optimized QCD design at 4.3 µm, with a room-temperature peak responsivity of 26.12 mA/W and a detectivity of 1.41 × 108 Jones. Additionally, all QCD designs exhibit higher-energy interband signals in the mid- to near-infrared, stemming from the InAs/AlSb type-II alignment and the narrow InAs band gap.

The InAs/GaSb superlattices (SPLs) was an important component of Quantum Cascade Laser (QCL) and Interband Cascade Laser (ICL). In particular, the upper and lower SPLs waveguide layers and active regions of the ICL were alternately grown from a large number of ultra-film epitaxial layers (nm) by Molecular Beam Epitaxy(MBE). Subtle lattice mismatch may directly lead to the deterioration of material crystal quality, and the thickness, which the composition change of each layer will strongly affect the structural performance of device materials. The optimal growth temperature of InAs/GaSb SPLs were about 420℃. By growing 40× short period GaSb/AlSb and InAs/GaSb SPLs with the substrate rotating, the thickness of GaSb and AlSb layers were 5.448 nm and 3.921 nm, and the thickness of InAs and GaSb layers were 8.998 nm and 13.77 nm, respectively. The error was about 10%, and the optimal growth conditions of InAs/AlSb SPLs were obtained. Due to the lattice matched, the 40× InAs/away as injection on the average lattice constant of InAs/AlSb SPLs were fully considered. Under the condition that the soak time was fixed by 3s, the average lattice constant of SPLs was adjusted by changing the as pressure to 1.7e^-6 mbar to achieve lattice matching on the GaSb substrate. The results showed that the 0 order satellite peak of the SPLs coincides with the peak of the GaSb substrate, indicated perfect lattice matching, and the sharp of second order satellite peak also showed excellent structural quality of the SPLs structure.

La détection sensible et sélective des BTEX et du propane présente un grand intérêt pour les applications environnementales, biomédicales et pétrochimiques. Cependant, la détection de ces composés est compliquée à cause des interférences potentielles, soit entre eux, soit avec d'autres composés. Ce problème peut être résolu par la spectroscopie laser à de grandes longueurs d'onde (13-15 µm), où ils présentent des caractéristiques d'absorption très discriminantes. Pourtant, cette gamme spectrale est pratiquement inexplorée en raison du manque de sources appropriées. Cette thèse vise à combler cette lacune en développant des LCQ émettant à des grandes longueurs d'onde élevées et en exploitant le QEPAS pour une détection ultra-sensible et sélective.Un nouveau design est proposé pour améliorer les performances des LCQ à base d'InAs de grande longueurs d'onde. Cette conception nous a permis de démontrer une densité de courant de seuil record de 0,6 kA/cm2 à 300 K. En outre, une nouvelle technique d'isolation utilisant le SOG est également proposée pour améliorer les problèmes de stabilité du dispositif provoqués par l'altération des propriétés de l'isolation de la résine photosensible (généralement utilisée pour les QCL à base d'InAs) à des températures élevées. Par la suite, des QCL DFB monomodes avec un SMSR > 20 dB et une puissance de sortie optique de l'ordre du mW ont été développé, ciblant les lignes d'absorption de ces gaz. En utilisant ces lasers, un système de détection basé sur le QEPAS a été développé, calibré et caractérisé pour la détection du toluène, du benzène et du propane. Des limites de détection exceptionnellement basses de 113 ppb, 3 ppb et 3 ppm sont atteintes dans une matrice d'azote pur sur un temps d'intégration de 10 secondes. Le système conserve sa sélectivité et sa robustesse, même dans des mélanges de gaz complexes. Enfin, une QCL de 13,71 µm est couplée avec succès à un HCW, où les conditions optimales de couplage, la qualité du faisceau et la perte sont explorées. L'étude confirme la transmission efficace d'une telle longueur d'onde à travers le HCW avec une perte minimale et une qualité de faisceau spatial améliorée
Sensitive and selective sensing of BTEX and Propane is of great interest for environmental, biomedical, and petrochemical applications. However, detecting these compounds poses unique challenges due to potential interferences, either among themselves or from other compounds. This issue can be resolved by using laser spectroscopy in the long-wavelength mid-infrared spectral region (13-15 µm), where they exhibit highly discriminating absorption features. Yet, this wavelength range is almost unexplored due to the lack of suitable sources. This thesis aims to bridge this gap by developing high-performing long-wavelength QCLs and leveraging QEPAS for ultra-sensitive and selective detection.A novel design is proposed to improve the performance of long-wavelength InAs-based QCLs, which allowed us to demonstrate a record-breaking low threshold current density of 0.6 kA/cm2 at 300 K. Additionally, a novel insulation technique using SOG is also proposed to improve device stability issues provoked by the alteration of properties of photoresist insulation (typically used for InAs-based QCLs) at elevated temperatures. Subsequently, single-frequency DFB QCLs with SMSR > 20 dB and optical output power in the mW range operating in the continuous wave regime are developed, targeting the absorption lines of these gasses. Using these DFBs, a sensing system based on QEPAS is developed, calibrated, and characterized for Toluene, Benzene, and Propane detection. Exceptionally low detection limits of 113 ppb, 3 ppb, and 3 ppm are achieved in a pure nitrogen matrix over a 10-second integration time. The system maintains selectivity and robustness, even in complex gas mixtures. Finally, a 13.71 µm QCL is successfully coupled with a HCW, where optimal coupling conditions, beam quality, and loss are explored. The study confirms the efficient transmission of such wavelength through HCW with minimal loss and improved spatial beam quality

Disertaciniame darbe nagrinėjamas InAs/AlSb medžiagų sistemos panaudojimas trumpabangių tarppajuostinių lazerių kūrimui. Buvo išplėtota molekulinių pluoštelių epitaksijos technologija, leidžianti auginti daugiaperiodines neįtemptas InAs/AlSb heterosandūras su mažu 1-2 atominių sluoksnių šiurkštumu. Buvo parodyta, jog InAs/AlSb medžiagų sistema yra tinkama kurti trumpabangiams kvantiniams kaskadiniams lazeriams, veikiantiems žemiau 4 µm bangos ilgio ribos. Buvo ištirtas kvantinių kaskadinių lazerių, turinčių tiek plazmoninius bangolaidžius su stipriai legiruotais InAs apdariniais sluoksniais, tiek ir mažo periodo InAs/AlSb supergardelių bangolaidžius, veikimas bei jų įtaka prietaiso parametrams. Šie sprendimai dėl bangolaidžių bei tolimesni aktyviosios terpės patobulinimai, naudojant piltuvėlio formos injektorių, leido sukurti didelio našumo prietaisus, galinčius veikti iki 420 K temperatūros, esant 3,3 µm bangos ilgio emisijai, ir pasiekti maksimalią optinę galią siekiančią 1 W kambario temperatūroje. Šios inovacijos leido sukurti ir InAs/AlSb kvantinį kaskadinį lazerį, emituojantį ~2,6 µm bangos ilgio spinduliuotę  šiai dienai tai yra trumpiausią bangos ilgį spinduliuojantis tokio tipo prietaisas pasaulyje.
Application of InAs/AlSb materials system for development of short-wavelength quantum cascade lasers is explored. Molecular beam epitaxy (MBE) technology allowing to grow multiperiodical unstrained InAs/AlSb heterostructures with roughness of 1-2 monolayers is developed. It is demonstrated that InAs/AlSb materials system is well-suitable for development of short-wavelength quantum cascade lasers operating below 4 µm wavelength. Lasers containing plasmon-enhanced waveguides as well as the short period InAs/AlSb superlattices as waveguides were designed, MBE-grown and studied. The effect of waveguide properties on the device parameters is revealed. Usage of these waveguides and innovations in laser active region introducing “funnel” injector allowed one to reach operation temperature 420 K at the emission wavelength of 3.3 µm. The obtained optical peak power exceeded 1 W per facet. The room temperature operation has been obtained at wavelength below 3 µm. As for wavelength range, applying the new active region design strategy and the short period InAs/AlSb superlattice spacers InAs based quantum cascade lasers emitting at the wavelengths as short as 2.63 µm were developed, which is today the shortest emission wavelength of the operation of semiconductor lasers based on the intersubband transitions.

Application of InAs/AlSb materials system for development of short-wavelength quantum cascade lasers is explored. Molecular beam epitaxy (MBE) technology allowing to grow multiperiodical unstrained InAs/AlSb heterostructures with roughness of 1-2 monolayers is developed. It is demonstrated that InAs/AlSb materials system is well-suitable for development of short-wavelength quantum cascade lasers operating below 4 µm wavelength. Lasers containing plasmon-enhanced waveguides as well as the short period InAs/AlSb superlattices as waveguides were designed, MBE-grown and studied. The effect of waveguide properties on the device parameters is revealed. Usage of these waveguides and innovations in laser active region introducing “funnel” injector allowed one to reach operation temperature 420 K at the emission wavelength of 3.3 µm. The obtained optical peak power exceeded 1 W per facet. The room temperature operation has been obtained at wavelength below 3 µm. As for wavelength range, applying the new active region design strategy and the short period InAs/AlSb superlattice spacers InAs based quantum cascade lasers emitting at the wavelengths as short as 2.63 µm were developed, which is today the shortest emission wavelength of the operation of semiconductor lasers based on the intersubband transitions.
Disertaciniame darbe nagrinėjamas InAs/AlSb medžiagų sistemos panaudojimas trumpabangių tarppajuostinių lazerių kūrimui. Buvo išplėtota molekulinių pluoštelių epitaksijos technologija, leidžianti auginti daugiaperiodines neįtemptas InAs/AlSb heterosandūras su mažu 1-2 atominių sluoksnių šiurkštumu. Buvo parodyta, jog InAs/AlSb medžiagų sistema yra tinkama kurti trumpabangiams kvantiniams kaskadiniams lazeriams, veikiantiems žemiau 4 µm bangos ilgio ribos. Buvo ištirtas kvantinių kaskadinių lazerių, turinčių tiek plazmoninius bangolaidžius su stipriai legiruotais InAs apdariniais sluoksniais, tiek ir mažo periodo InAs/AlSb supergardelių bangolaidžius, veikimas bei jų įtaka prietaiso parametrams. Šie sprendimai dėl bangolaidžių bei tolimesni aktyviosios terpės patobulinimai, naudojant piltuvėlio formos injektorių, leido sukurti didelio našumo prietaisus, galinčius veikti iki 420 K temperatūros, esant 3,3 µm bangos ilgio emisijai, ir pasiekti maksimalią optinę galią siekiančią 1 W kambario temperatūroje. Šios inovacijos leido sukurti ir InAs/AlSb kvantinį kaskadinį lazerį, emituojantį ~2,6 µm bangos ilgio spinduliuotę  šiai dienai tai yra trumpiausią bangos ilgį spinduliuojantis tokio tipo prietaisas pasaulyje.

This chapter focuses on the rise of Chicago's gospel quartets, hailed as the “rock stars of religious music” by music historian Al Young, after World War II. The postwar migration to Chicago coincided with the rise to national prominence of the male gospel quartet. Quartets such as the Soul Stirrers, the Pilgrim Travelers, and the Harmonizing Four were packing auditoriums with exciting live performances, singing on hundreds of radio stations, and sellling records by the tens of thousands. This chapter first takes a look at the gospel music of the Soul Stirrers before turning to churches and venues featuring local and traveling quartets. It then considers other quartets and gospel singers, including Sam Cooke and Paul Foster, R. H. Harris and the Christland Singers, the Highway QCs, Johnnie Taylor, James Phelps and the Clefs of Calvary, and Roscoe Robinson. It also discusses three quartets that formed in the South, migrated to Chicago, and became nationally recognized artists: the Pilgrim Jubilee Singers, the Kelly Brothers, and the Norfleet Brothers.

This chapter describes the most commonly used approaches for computing the band structure of active materials with intersubband optical transitions. The physics of quantum cascade lasers (QCLs) is discussed in detail, including the mechanisms that limit the threshold current density, threshold voltage, wall-plug efficiency, and temperature sensitivity of state-of-the-art devices. The important roles of phonon and interface roughness scattering in determining threshold are emphasized. The chapter also compares the performance of QCLs to other mid-IR lasers in considerable detail and makes some conclusions as to which sources are preferred depending on the emission wavelength and application. Finally, the physical principles of laser-based frequency combs, including self-starting frequency-modulated QCL combs, are discussed.

Economic emission dispatch (EED) problems are one of the most crucial problems in power systems. Growing energy demand, limited reserves of fossil fuel and global warming make this topic into the center of discussion and research. In this chapter, we will discuss the use and scope of different quantum inspired computational intelligence (QCI) methods for solving EED problems. We will evaluate each previously used QCI methods for EED problem and discuss their superiority and credibility against other methods. We will also discuss the potentiality of using other quantum inspired CI methods like quantum bat algorithm (QBA), quantum cuckoo search (QCS), and quantum teaching and learning based optimization (QTLBO) technique for further development in this area.

Economic emission dispatch (EED) problems are one of the most crucial problems in power systems. Growing energy demand, limited reserves of fossil fuel and global warming make this topic into the center of discussion and research. In this chapter, we will discuss the use and scope of different quantum inspired computational intelligence (QCI) methods for solving EED problems. We will evaluate each previously used QCI methods for EED problem and discuss their superiority and credibility against other methods. We will also discuss the potentiality of using other quantum inspired CI methods like quantum bat algorithm (QBA), quantum cuckoo search (QCS), and quantum teaching and learning based optimization (QTLBO) technique for further development in this area.

We meet our hosts, Alice and Bob, and an undergraduate student, Cardy. Alice and Bob tell Cardy why QC is “the next big thing.” They give a brief introduction to quantum information science (QIS) and its relation to quantum computing (QC). They also provide an overview of the rest of the book and how the book should be used to come to grips with quantum ideas that allow QCs to do things unimaginable for traditional computers. Alice and Bob emphasize that with perseverance everyone can understand the fundamentals of QC and how quantum physics enables entirely new ways of thinking about computational algorithms. They explain the book’s overarching narrative: quantum states, quantum entanglement, and quantum measurements provide the essential resources for QC and QIS.

THz quantum cascade lasers (QCLs) [1,2] are promising high output power semiconductor THz sources to over Watt order peak power [3] with narrow bandwidth. It is still quite limited for the THz applications caused by the large cryogenic system and low duty cycle with low output power at high operation temperature. Output power is one of the most critical parameters for real applications. We demonstrated a 77 K liquid nitrogen Dewar condenser as a compromised compact portable THz source unit with our fabricated QCLs. They showed a stable few ten mW peak power with sub mW average power operation. Analysis the temperature performance of structures by Non-Equilibrium Green’s Function (NEGF) method are discussed. The improvement of the active region and waveguide fabrication will also be discussed for high output power operation in order to exhibit the best performance of the compact 77 K Dewar system.

In the last decade, quantum confined semiconductor structures (QCSS) have attracted much attention because of their novel properties and their potential for electronic and photonic applications [1]. Quantum size effects appear in a semiconductor structure when one of its dimensions is in the range 10Å <L<500 Å. In these materials the typical values of group and phase velocities of elementary excitations are such that the corresponding times are in the range 10fs<t<500fs. Therefore reduced dimensionality also implies ultrafast dynamics. In this talk we review the most significant results obtained in the investigation of ultrafast processes in QCSS. We also describe recent experiments that reveal some open questions in ultrafast physics of QCSS, which we discuss. The present summary gives a flavor of the topics covered by the lecture.

Qualitative Choice Logic (QCL) and Conjunctive Choice Logic (CCL) are formalisms for preference handling, with especially QCL being well established in the field of AI. So far, analyses of these logics need to be done on a case-by-case basis, albeit they share several common features. This calls for a more general choice logic framework, with QCL and CCL as well as some of their derivatives being particular instantiations. We provide such a framework, which allows us, on the one hand, to easily define new choice logics and, on the other hand, to examine properties of different choice logics in a uniform setting. In particular, we investigate strong equivalence, a core concept in non-classical logics for understanding formula simplification, and computational complexity. Our analysis also yields new results for QCL and CCL. For example, we show that the main reasoning task regarding preferred models is ϴ₂P-complete for QCL and CCL, while being Δ₂P-complete for a newly introduced choice logic.

<div class="section abstract"><div class="htmlview paragraph">The Euro 7 emission regulations currently under consideration by the EU will adopt on-road emissions test as the main Type Approval procedure, and it has been proposed that the number of gas components to be measured will be increased. Therefore, the Portable Emissions Measurement System (PEMS) used for on- road emissions testing must be able to simultaneously measure more components with higher precision while maintaining the same compact and lightweight structure as in the existing PEMS. The authors have applied a relatively new technique, quantum cascade laser infrared spectroscopy (QCL-IR), to an on-board multi-component gas analyzer. Comparison with laboratory tests on a gasoline passenger car on a dynamometer showed that the newly developed QCL- IR PEMS correlated well with conventional PEMS and stationary conventional analyzers. Signal noise and interference from other gases was also confirmed to show the expected performance, which was equal to or better than that of conventional analyzers.</div></div>

Abstract A new method was developed on High Performance Liquid Chromatography (HPLC) instrument equipped with a Photodiode Array UV detector to determine the Nitrite-Nitrogen and Nitrate-Nitrogen in seawater, industrial wastewater, and groundwater at very low concentrations. This HPLC used a reverse phase system with polar mobile phase and nonpolar C-18 Column. The split mechanism of the HPLC Chromatography was accomplished by employing acetonitrile and acidified water with pH 2.5, at 55:45 ACN: H2O v/v as a mobile phase, long HPLC Column (C-18, 0.5 μm, 250 × 4.6 mm) and at 1 mL/min flow rate. The calibration curves of nitrate-nitrogen and nitrite-nitrogen in the range of 0.05 to 1.0 mg/L were exceptionally linear with correlation coefficients greater than 0.999 and with low Method Detection Limit (MDL) of 0.02 mg/L for both of NO2-n and NO3-n. This developed method also showed comparable results to the ones obtained by the traditional SKALAR instrument which follows ASTM D3867 Automated Cadmium Reduction Method. The results of the nitrate-n and nitrite-n for the Quality Control Samples (QCS) and the average recoveries percentage of the spiked samples demonstrated high accuracy values 99.20% - 101.40% & 98.4% - 99.1% respectively. The very low detection limit is what set this study apart from the previous conducted studies on nitrate and nitrite determination by HPLC. This new developed method is safer and with minimal cost compared to the traditional cadmium reduction method. It doesn't consume water, or require preparation of many hazardous reagents that contain and generate cadmium wastes.

Performance of current NOx sensors is problematic, in particular drift and cross-sensitivity to other species. Many lean burn engines are operated based on earlier calibrations. Operators must allow for drift and use large margins to meet emissions. Laser sensors (based on absorption at target wavelengths) are self-calibrating and immune to interferences. In particular, recently developed Quantum Cascade Lasers (QCLs) allow measurements at mid-infrared (MIR) wavelengths thereby allowing stronger signals, better schemes to mitigate interferences, and fast time response. This project evaluated a commercial QCL-based NOx (NO, NO2) and CO sensor for use in gas engine applications. The project also developed and performed bench top testing of a custom sensor which uses a �pitch and catch� design.