- 标题
- 摘要
- 关键词
- 实验方案
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EXPRESS: Mid-Infrared Reflectance Spectroscopy of Oil Sands Minerals Based on Tunable Quantum Cascade Lasers
摘要： Minerals play an important role in the oil sands extraction efficiency. It is thus important to assess the major mineral abundance in oil sands ores. This paper presents the application of tunable quantum cascade lasers for mid-infrared reflectance spectroscopy on oil sands minerals. The investigations and results show a new tool to determine oil sands mineral type and to determine potentially quartz and clay contents.
关键词： Mid-infrared spectroscopy,mid-IR,reflectance spectroscopy,oil sands,QCL,quantum cascade lasers
更新于2025-09-23 15:21:01
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Biomedical applications of mid-infrared quantum cascade lasers – a review
摘要： Mid-infrared spectroscopy has been applied to research in biology and medicine for more than 20 years and conceivable applications have been identified. More recently, these applications have been shown to benefit from the use of quantum cascade lasers due to their specific properties, namely high spectral power density, small beam parameter product, narrow emission spectrum and, if needed, tuning capabilities. This review provides an overview of the achievements and illustrates some applications which benefit from the key characteristics of quantum cascade laser-based mid-infrared spectroscopy using examples such as breath analysis, the investigation of serum, non-invasive glucose monitoring in bulk tissue and the combination of spectroscopy and microscopy of tissue thin sections for rapid histopathology.
关键词： quantum cascade lasers,glucose monitoring,mid-infrared spectroscopy,histopathology,breath analysis,biomedical applications
更新于2025-09-19 17:15:36
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Efficient Tm:LiYF4 Lasers at ～2.3 lm: Effect of Energy-Transfer Upconversion
摘要： The 3H4 → 3H5 transition of Thulium ions (Tm3+), which features laser emission at ~2.3 μm is studied in details. We revise the conditions for efficient laser operation using a rate- equation model accounting for the ground-state bleaching, cross- relaxation and energy-transfer upconversion (ETU). We show that ETU has a crucial role in reaching more than unity pump quantum efficiency (QE) for ~2.3 μm Tm lasers based on highly- doped crystals. A Ti:Sapphire pumped quasi-continuous-wave 3.5 at.% Tm:LiYF4 laser generated 0.73 W at 2306 nm with a record-high slope efficiency of 47.3% (versus the absorbed pump power, for double-pass pumping) featuring a QE of 1.27. Diode- pumping of this crystal yielded a peak output power of >2 W. The first 2.3 μm Tm waveguide laser is also reported based on Tm:LiYF4 epitaxial layers with even higher doping of 6.2 at.% generating 0.23 W with a slope efficiency of 19.8%. The spectroscopic properties of Tm:LiYF4 relevant for the ~2.3 μm laser operation are revised as well.
关键词： mid-infrared,spectroscopy,laser transitions,Solid-state lasers
更新于2025-09-19 17:13:59
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Dynamic Ligand Surface Chemistry of Excited PbS Quantum Dots
摘要： The ligand shell around colloidal quantum dots mediates the electron and energy transfer processes that underpin their use in optoelectronic and photocatalytic applications. Here, we show that the surface chemistry of carboxylate anchoring groups of oleate ligands passivating PbS quantum dots undergoes significant changes when the quantum dots are excited to their excitonic states. We directly probe the changes of surface chemistry using time-resolved mid-infrared spectroscopy that records the evolution of the vibrational frequencies of carboxylate groups following excitation of the electronic states. The data reveal a reduction of the Pb?O coordination of carboxylate anchoring groups to lead atoms at the quantum dot surfaces. The dynamic surface chemistry of the ligands may increase their surface mobility in the excited state and enhance the ability of molecular species to penetrate the ligand shell to undergo energy and charge transfer processes that depend sensitively on distance.
关键词： surface chemistry,PbS quantum dots,ligand shell,colloidal quantum dots,time-resolved mid-infrared spectroscopy
更新于2025-09-19 17:13:59
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Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source
摘要： Fourier transform infrared (FT-IR) spectrometers have been the dominant technology in the field of mid-infrared (mid-IR) spectroscopy for decades. Supercontinuum laser sources operating in the mid-IR spectral region now offer the potential to enrich the field of FT-IR spectroscopy due to their distinctive properties, such as high-brightness, broadband spectral coverage and enhanced stability. In our contribution, we introduce this advanced light source as a replacement for conventional thermal emitters. Furthermore, an approach to efficient coupling of pulsed mid-IR supercontinuum sources to FT-IR spectrometers is proposed and considered in detail. The experimental part is devoted to pulse-to-pulse energy fluctuations of the applied supercontinuum laser, performance of the system, as well as the noise and long-term stability. Comparative measurements performed with a conventional FT-IR instrument equipped with a thermal emitter illustrate that similar noise levels can be achieved with the supercontinuum-based system. The analytical performance of the supercontinuum-based FT-IR spectrometer was tested for a concentration series of aqueous formaldehyde solutions in a liquid flow cell (500 mm path length) and compared with the conventional FT-IR (130 mm path length). The results show a four-times-enhanced detection limit due to the extended path length enabled by the high brightness of the laser. In conclusion, FT-IR spectrometers equipped with novel broadband mid-IR supercontinuum lasers could outperform traditional systems providing superior performance, e.g., interaction path lengths formerly unattainable, while maintaining low noise levels known from highly stable thermal emitters.
关键词： Mid-infrared spectroscopy,mid-IR,supercontinuum laser source,Fourier transform infrared spectroscopy,FT-IR
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Breath Signatures of Cerebral Palsy Patients Revealed with Mid-Infrared FTIR Spectroscopy
摘要： In the absence of “broadband” objective medical diagnostics, photonics technologies are now considered as a promising way to establish it. For example, being applied to human breath, under right conditions they should allow for unambiguous identification of metabolites circulating in blood and released in lungs alveoli as volatile organic compounds (VOCs). Nowadays, tremendous progress is achieved in developing laser-based mid-infrared spectrometers highly sensitive to VOCs [1,2]. Still, the spectral range covered by the laser spectrometers demonstrated so far, and signal-to-nose ratio (SNR) are not superior to conventional FTIR spectrometers based on thermal source. A significant amount of water vapour in breath is another, though general for all techniques, severe problem for VOCs detection. In addition to the detection, data analysis should be advanced in order to accurately compare healthy and diseased cohorts under study.
关键词： cerebral palsy,FTIR spectroscopy,mid-infrared spectroscopy,breath analysis,VOCs
更新于2025-09-16 10:30:52
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Enhanced RDX Detection Studies on Various Types of Substrates via Tunable Quantum Cascade Laser Spectrometer Coupled with Grazing Angle Probe
摘要： Owing to scientific advances in the field of materials sciences and engineering, researchers have developed new energy sources used for spectroscopic applications and measurements of properties resulting from the interaction of matter and electromagnetic radiation in the mid-infrared (MIR) region. MIR lasers, such as quantum cascade lasers (QCLs), used for spectroscopy have quickly found numerous applications in a wide cadre of IR techniques. This provides the opportunity to study properties of highly energetic materials (HEM), among many other applications. MIR laser spectroscopy based detection experiments of HEMs were carried out using a QCL optically coupled to compact grazing angle probe mount (QCL-GAP) enabling reflection-absorption infrared spectroscopy (RAIRS) measurements of thin films of HEMs. A saturated solution of RDX in acetone was prepared, and aliquots of subsequent dilutions of the stock solutions were transferred to test surfaces for QCL-GAP back-reflectance measurements. RDX reflectance signals were monitored as function as the decreasing surface concentration until the signal/noise was ~ 3. Stainless steel (SS) plates were used as reflective substrates, and anodized aluminum (AN-Al), cardboard, and Teflon were used as non-reflective (matte) substrates. Using generated calibration curves a low limit of detection (LOD) of 1.7 ng/cm2 for RDX/SS and 95 μg/cm2 for RDX/AN-Al were found. Based on the area of laser spot (0.3 cm2) we conclude the minimum masses detected were 490 pg (RDX/SS) and 28 μg (RDX/AN-Al).
关键词： Quantum Cascade Laser,RDX detection,Grazing Angle Probe,Highly Energetic Materials,Mid-Infrared Spectroscopy
更新于2025-09-16 10:30:52
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EXPRESS: External Cavity Quantum Cascade Laser-Based Mid-Infrared Dispersion Spectroscopy for Qualitative and Quantitative Analysis of Liquid-Phase Samples
摘要： Acquisition of classical absorption spectra of liquids in the mid-IR range with quantum cascade lasers (QCLs) is often limited in sensitivity by noise from the laser source. Alternatively, measurement of molecular dispersion (i.e., refractive index) spectra poses an experimental approach that is immune to intensity fluctuations and further offers a direct relationship between the recorded signal and the sample concentration. In this work, we present an external cavity quantum cascade laser (EC-QCL) based Mach–Zehnder interferometer setup to determine dispersion spectra of liquid samples. We present two approaches for acquisition of refractive index spectra and compare the qualitative experimental results. Furthermore, the performance for quantitative analysis is evaluated. Finally, multivariate analysis of a spectrally complex mixture comprising three different sugars is performed. The obtained figures of merit by partial least squares (PLS) regression modelling compare well with standard absorption spectroscopy, demonstrating the potential of the introduced dispersion spectroscopic method for quantitative chemical analysis.
关键词： liquid phase,Mid-infrared spectroscopy,QCL,quantum cascade laser,dispersion spectroscopy,mid-IR spectroscopy
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Mid-Infrared Sensing by Induced Coherence in a Single Nonlinear Waveguide
摘要： Induced coherence (IC) between two spatially separated but indistinguishable spontaneous parametric down conversion (SPDC) processes underpins the recent revival of nonlinear interferometry and has led to new applications in quantum imaging and mid-infrared (MIR) spectroscopy [1,2]. These applications exploit induced coherence and the spectral or spatial correlations between signal and idler photons generated through SPDC. Here, we theoretically describe the phenomenon of IC in a general way by making use of a quantum-mechanical approach based on the classical Green’s function (GF) of the system [3,4]. Our formalism is well suited for treating generic linear optical properties of a system, including loss, and studying their influence on the IC phenomena. Moreover, our approach can account for arbitrary spatial profiles of the nonlinearity and hence can be used to describe generalized IC experiments with different number of photon-pair sources. Here we propose a sensing experiment using a single nonlinear waveguide [5] and investigate IC using our formalism. We find that in this case a substance under test inside or surrounding the waveguide can affect the IC during the generation stage along the nonlinear waveguide, making this a compact scheme for MIR spectroscopy without the need for MIR detectors.
关键词： spontaneous parametric down conversion,quantum imaging,nonlinear interferometry,mid-infrared spectroscopy,induced coherence
更新于2025-09-11 14:15:04
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Flattened fiber-optic ATR sensor enhanced by silver nanoparticles for glucose measurement
摘要： This paper proposes a novel fiber attenuated total reflection (ATR) sensor with silver nanoparticles (AgNPs) on the flattened structure based on mid-infrared spectroscopy for detecting low concentration of glucose with high precision. The flattened structure was designed to add the effective optical path length to improve the sensitivity. AgNPs were then deposited on the surface of the flattened area of the fiber via chemical silver mirror reaction for further improving the sensitivity by enhancing the infrared absorption. Combining the AgNPs modified flattened fiber ATR sensor with a CO2 laser showed a strong mid-infrared glucose absorption, with an enhancement factor of 4.30. The glucose concentration could be obtained by a five-variable partial least-squares model with a root-mean-square error of 4.42 mg/dL, which satisfies clinical requirements. Moreover, the fiber-based technique provides a pretty good method to fabricate miniaturized ATR sensors that are suitable to be integrated into a microfluidic chip for continuous glucose monitoring with high sensitivity.
关键词： Attenuated total reflection sensor,Mid-infrared spectroscopy,Flattened structure,AgNPs,Continuous glucose monitoring
更新于2025-09-04 15:30:14