- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Terahertz generation in quantum-cascade lasers through down-conversion optical nonlinearity: Design and modeling
摘要： In this paper, we propose an electrically driven optically excited laser structure for terahertz (THz) generation in quantum cascade lasers (QCLs) through frequency down-conversion optical nonlinearity. In our distinct design, both the pump and THz radiations are generated simultaneously by optical and electronic intersubband transitions (ISTs) between the quantized states within the conduction band of the same active region of a QCL. The modeling of laser bandstructure is achieved using a self-consistent solution of Schrodinger-Poisson equations, and the detailed analysis of electronic transport of the proposed structure is performed using the density matrix approach and energy-density balance equation that self-consistently consider the optical, electrical and thermal interactions in the structure. Additionally, the waveguide loss for the THz optical mode is considered using the bulk Drude model. Using a stationary solution of the density matrix equations, an expression for the THz intensity gain is derived as a function of pump field intensity, carrier distributions and quantum coherence contributions. Using the presented model, we analyze the steady-state and transient characteristics of the device for two different heatsink temperatures, 220 and 300 K. Simulation results show that the proposed structure has a potential to generate room-temperature THz radiation in QCLs.
关键词： Quantum-cascade laser (QCL),terahertz (THz) generation,down-conversion optical nonlinearity,density-matrix formalism
更新于2025-09-23 15:21:01
-
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
-
Volume Fabrication of Quantum Cascade Lasers on 200 mm-CMOS pilot line
摘要： The manufacturing cost of quantum cascade lasers is still a major bottleneck for the adoption of this technology for chemical sensing. The integration of Mid-Infrared sources on Si substrate based on CMOS technology paves the way for high-volume low-cost fabrication. Furthermore, the use of Si-based fabrication platform opens the way to the co-integration of QCL Mid-InfraRed sources with SiGe-based waveguides, enabling realization of optical sensors fully integrated on planar substrate. We report here the fabrication and the characterization of DFB-QCL sources using top metal grating approach working at 7.4 μm fully implemented on our 200 mm CMOS pilot line. These QCL featured threshold current density of 2.5 kA/cm2 and a linewidth of 0.16 cm?1 with a high fabrication yield. This approach paves the way toward a Mid-InfraRed spectrometer at the silicon chip level.
关键词： Mid-Infrared sources,DFB-QCL sources,Si substrate,CMOS technology,Quantum Cascade Lasers
更新于2025-09-23 15:21:01
-
Advances in Mid-Infrared Spectroscopy-Based Sensing Techniques for Exhaled Breath Diagnostics
摘要： Human exhaled breath consists of more than 3000 volatile organic compounds, many of which are relevant biomarkers for various diseases. Although gas chromatography has been the gold standard for volatile organic compound (VOC) detection in exhaled breath, recent developments in mid-infrared (MIR) laser spectroscopy have led to the promise of compact point-of-care (POC) optical instruments enabling even single breath diagnostics. In this review, we discuss the evolution of MIR sensing technologies with a special focus on photoacoustic spectroscopy, and its application in exhaled breath biomarker detection. While mid-infrared point-of-care instrumentation promises high sensitivity and inherent molecular selectivity, the lack of standardization of the various techniques has to be overcome for translating these techniques into more widespread real-time clinical use.
关键词： point-of-care (POC),infrared lasers,MIR,photoacoustic spectroscopy,biomarkers,exhaled breath analysis,non-invasive diagnostics,QCL,quantum cascade lasers,mid-infrared
更新于2025-09-23 15:21:01
-
Jet-cooled rovibrational spectroscopy of methoxyphenols using two complementary FTIR and QCL based spectrometers
摘要： Methoxyphenols (MPs) are a significant component of biomass burning emissions which mainly exists in our atmosphere in the gas phase where they contribute to the formation of secondary organic aerosols (SOAs). Rovibrational spectroscopy is a promising tool to monitor atmospheric MPs and infer their role in SOA formation. In this study, we bring a new perspective on the rovibrational analysis of MP isomers by taking advantage of two complementary devices combining jet-cooled environments and absorption spectroscopy: the Jet-AILES and the SPIRALES setups. Based on Q-branch frequency positions measured in the Jet-AILES Fourier-transform infrared (FTIR) spectra and guided by quantum chemistry calculations, we propose an extended vibrational and conformational analysis of the different MP isomers in their fingerprint region. Some modes such as far-IR out-of-plane –OH bending or mid-IR in-plane –CH bending allow us to assign individually all the stable conformers. Finally, using the SPIRALES setup with three different external cavity quantum cascade laser sources centered on the 930–990 cm?1 and the 1580–1690 cm?1 ranges, it was possible to proceed to the rovibrational analysis of the ν18 ring in-plane bending mode of the MP meta isomer providing a set of reliable excited state parameters, which confirms the correct assignment of two conformers. Interestingly, the observation of broad Q-branches without visible P- and R-branches in the region of the C–C ring stretching bands was interpreted as being probably due to a vibrational perturbation. These results highlight the complementarity of broadband FTIR and narrowband laser spectroscopic techniques to reveal the vibrational conformational signatures of atmospheric compounds over a large infrared spectral range.
关键词： SPIRALES,Jet-AILES,methoxyphenols,FTIR,vibrational perturbation,conformational analysis,rovibrational spectroscopy,QCL
更新于2025-09-16 10:30:52
-
[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Active Hyperspectral Mid-Infrared Imaging Based on Widely Tunable QCL Laser
摘要： Thermal imaging and the recent availability of widely tunable infrared QCL lasers (Quantum Cascade Laser) allow us to propose an active hyperspectral imaging system operating in mid-infrared (MIR) band to obtain simultaneously large amounts of spatial and spectral information on the samples. In order to evaluate more precisely the capacities of the active hyperspectral imaging, we propose a system composed of four powerful QCL tunable lasers (in order to cover 3 – 5 μm and 7 – 11 μm wavelengths) and three cameras: a visible and near-infrared (NIR) range, a bolometer for 7 – 13 μm range and an InSb cooled camera for 3 – 5 μm range. We present the algorithm for image acquisition, image and data processing. Finally, we present and discuss some preliminary results using this system to characterize plant leaves under controlled growing conditions.
关键词： plant monitoring,tunable QCL laser,mid-infrared,hyperspectral imaging,image processing
更新于2025-09-16 10:30:52
-
[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) - Extended-Cavity-Quantum-Cascade-Laser-Voltage Intracavity Sensing and Application to Atmospheric Gas Detection
摘要： Laser spectrometers based on Quantum Cascade Lasers (QCL) provide good results for gas sensing in terms of sensibility and selectivity thanks to the characteristics of these sources. Distributed feedback (DFB) configuration provides narrow linewidth that enhances selectivity and their emission in the mid-IR enables to reach the fundamental absorption bands of molecules. The main limitation of these sources is their narrow tuning range (~ 10 cm-1) that prevents from monitoring complex species with broad absorption spectra or realizing multi-gas sensing. To obtain a broader tuning range, one solution consists of QCL DFB array with an arrayed waveguide grating to perform multi-species spectroscopy [1]. A more common technique is to implement the laser in an external cavity system. In GSMA, a commercial Extended-Cavity Quantum Cascade Laser emitting at 10.5 μm has been used to demonstrate photoacoustic gas sensing of heavy molecules such as butane [2] and a lab-made EC-QCL emitting at 7.5 μm was developed for detection of acetone and POCl3 in gas phase [3]. Moreover, the use of an external cavity allows the possibility to perform Intra-Cavity Laser Absorption Spectroscopy (ICLAS). In this method the sample is placed within the laser resonator. Absorption lines of the sample imprint signatures on the spectrum because they influence it during many round trips. The cavity output light is detected to perform spectroscopy. The used QCL developed by mirSense is operated in cw operation at room temperature and emits from 7.4 to 7.8 μm. A technique using the QCL compliance voltage [4] called EVIS (EC-QCL Voltage Intracavity Sensing) is used to retrieve the spectrum of the gas inside the cavity. This way no detector outside the cavity is needed. With gas inside the cavity, losses rise implies a variation of intracavity intensity thus a variation of laser voltage. The large wavenumber sweeping is performed through the grating rotation and the variation of QCL current supply permits to obtain a small wavelength variation. In order to suppress the QCL mode hops influence, a current ramp is applied so that the small wavelength total variation is equal to 1 QCL mod hop. Then QCL voltage is recorded during the current ramp, for all grating positions, and a numerical treatment is performed to improve the signal. Fig. 1 presents a result of this measurement (on the left) compared with the absorption coefficient calculated from the HITRAN database [www.hitran.org] (on the right). This measurement corresponds to a cavity filled with 0.3% of CH4 in air (containing water vapor) at atmospheric pressure. This preliminary result shows a good agreement between the voltage difference and the calculated absorption coefficient. The resolution is estimated to approx. 0.1 cm-1.
关键词： Quantum Cascade Lasers,gas sensing,ICLAS,Intra-Cavity Laser Absorption Spectroscopy,EVIS,EC-QCL Voltage Intracavity Sensing,QCL
更新于2025-09-12 10:27:22
-
[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) - Wavelength Stabilized External Cavity Quantum Cascade Lasers using Cavity Resonator Integrated Grating Filters
摘要： External cavity diode lasers (ECDLs) are a standard way of building single-mode and narrow-linewidth sources [1], while keeping the intrinsic benefits of semiconductor lasers like compactness, low-cost and high-modulation capability. Traditional ECDLs design uses a bulk diffraction grating in Littrow or Littman/Metcalf configurations. In this paper, we report on the use of recently demonstrated MIR Cavity Resonator Integrated Grating Filters (MIR-CRIGFs) [2] to implement an alternative configuration using a compact and stable cat’s-eye configuration. The external cavity under study is made of a 4.5 μm QCL laser grown on InP substrate with an HR coating on the rear facet and an optimized AR coating on the front facet. An intracavity lens (f=1.87 mm) images the AR coated facet onto a CRIGF used both as a cavity end-mirror and a spectral filter. The total cavity length is short, estimated around 4.2 cm. The initial cavity alignment is straightforward thanks to the high sensitivity of the QCL gain chip to optical feedback, monitored through injection voltage. On figure 1, the different CRIGFs are clearly visible (large white rectangles arranged on two 6x10 matrices with varying geometrical parameters). CRIGFs where the central GC appears as a dark narrow vertical stripe are the one inducing the highest optical feedback in the QCL. They correspond to the CRIGFs spectrally matched with the QCL gain medium and able to stabilize the emitted frequency.
关键词： External cavity diode lasers,MIR Cavity Resonator Integrated Grating Filters,wavelength stabilisation,QCL laser
更新于2025-09-11 14:15:04
-
[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) - Advances in MOEMS-Based External Cavity QCLs
摘要： The combination of broadband quantum cascade lasers (QCLs) with a micro-electro-mechanical system (MOEMS) scanner with integrated diffraction grating as a wavelength-selective and optical feedback providing element enables the realization of compact, portable and robust spectroscopy systems. As previously showed [1–2], such MOEMS-based external cavity (EC)-QCLs configurations lead to measurement times as low as ~1 millisecond per QCL-tuning range (hundreds of cm-1) while eliminating the need of homodyne detection systems, such as lock-in electronics. Also non-resonant (quasistatic) MOEMS grating scanners providing scan rates of tens of Hz as well as static setting of arbitrary wavelengths are possible, keeping the advantage of using small MOEMS footprints, ruggedness, and low power consumption. Here we review our latest developments in MOEMS-based EC-QCLs made by Fraunhofer IAF and IPMS. We present a miniaturized, non-resonant MOEMS EC-QCL that allows scan frequencies of few tens of Hz (as well as static operation) together with an excellent wavelength reproducibility within a small and compact device. Static-controllable MOEMS EC-QCLs are of high interest for spectroscopy applications that require both arbitrary tuning speeds (e.g. large time constants as in photothermal or photoacoustic spectroscopy) and discrete wavelength tuning. Such tuning speeds are not achievable with resonantly-driven MOEMS scanners, as their mechanical resonance frequency remains >120 Hz. Both requirements can be well fulfilled with static-controllable MOEMS EC-QCLs independently of the QCL gain bandwidth characteristics. We also present a resonantly-driven continuous wave (cw) MOEMS EC-QCL with cavity-length control to enable fast high-resolution fast spectroscopy over a spectral range of >100 cm-1 and discuss our progress towards a dispersion-free beam spot radius for MOEMS EC-QCLs and our approach to operate MOEMS EC-QCLs in a permanent low-noise regime.
关键词： wavelength tuning,QCL,external cavity,spectroscopy,MOEMS
更新于2025-09-11 14:15:04
-
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