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[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) - Fabrication of Gratings in Mid-Infrared Compatible Fibres via Femtosecond Laser Direct Inscription
摘要： We report on research into the fabrication of different types of gratings into optical fibres that are transparent at mid-infrared wavelengths. In particular, we focus on direct femtosecond laser inscription of fibre-Bragg gratings with parallel as well as with tilted grating planes into zirconium and indium fluoride fibres. It is shown that post-annealing of the gratings can lead to an increase or decrease in reflectivity depending on the fabrication method and that even a relatively low concentration of rare-earth ions that are present in active fibres can have a big influence on the inscription process. Further, the feasibility investigating the physical mechanisms that underpin the induced refractive index modulation by utilising argon-beam cross-sectional polishing of the inscribed fibres followed by spatially resolved Raman microscopy and electron probe microanalysis, is discussed.
关键词： tilted fibre Bragg gratings,femtosecond-laser inscription,mid-infrared fibres,fluoride fibres,fibre Bragg gratings
更新于2025-09-16 10:30:52
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Optical spectroscopy studies of atom intermixing in the core versus growth temperature of the claddings in MOCVD-grown quantum cascade lasers
摘要： Here we present optical spectroscopy studies to examine structural and optical properties of active region of quantum cascade lasers grown fully by MOCVD technique. The active part is InGaAs/AlInAs based multilayer structure nominally lattice matched to InP substrate. In this communication we study a set of structures with different growth temperature of the cladding layers and its influence on the properties of active core. The x-ray spectroscopy (XRD) allowed to determine the widths of constituent layers and compare obtained values with nominal ones. Fourier-transformed photoluminescence (FTPL) and photoreflectance (PR) measurements provided high signal to noise spectra, proving good optical and structural properties of investigated samples. A model of atoms interdiffusion processes was presented to explain observed small energy shifts of the transitions energies within the investigated multilayer structures.
关键词： MOCVD,optical spectroscopy,semiconductors,mid infrared,atoms interdiffusion,quantum cascade lasers
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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Tunable passively Q-switched Dy <sup>3+</sup> -doped fiber laser from 271 to 308??μm using PbS nanoparticles
摘要： We present the first widely tunable passively Q-switched Dy3+-doped ZBLAN fiber laser around 3 μm pumped at 1.1 μm using PbS nanoparticles as the saturable absorber (SA) to our knowledge. At 2.87 μm, the modulation depth and saturation intensity of the SA were measured to be 12.5% and 1.10 MW∕cm2, respectively. Stable Q-switching was achieved over a wavelength range of 2.71–3.08 μm (～370 nm), which is a record tuning range from a pulsed rare-earth-doped fiber laser, to our knowledge. A maximum output power of 252.7 mW was obtained, with a pulse energy of 1.51 μJ, a pulse width of 795 ns, and a repetition rate of 166.8 kHz. This demonstration implies that Dy3+ is a promising gain medium for tunable pulsed sources in the 3 μm band and shows for the first time, to the best of our knowledge, the potential of PbS as a mid-infrared SA.
关键词： Dy3+-doped ZBLAN fiber laser,passively Q-switched,PbS nanoparticles,mid-infrared,tunable
更新于2025-09-16 10:30:52
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Si-based GeSn photodetectors towards mid-infrared imaging applications
摘要： The GeSn detector offers the high-performance Si-based infrared photodetectors with complementary metal-oxide-semiconductor (CMOS) technique compatibility. In this work, we reports a comprehensive study of Si-based GeSn mid-infrared photodetectors, which includes: i) the demonstration of a set of photoconductors with Sn compositions ranging from 10.5% to 22.3%, showing the cut-off wavelength has been extended to 3.65 μm. The maximum D* of 1.1×1010 cm?Hz1/2?W-1 measured at 77 K is comparable to that of commercial extended-InGaAs detectors; ii) the development of surface passivation technique on photodiode based on in-depth analysis of dark current mechanism, effectively reducing the dark current. Moreover, mid-infrared images were obtained using GeSn photodetectors, showing the comparable image quality with that acquired by using commercial PbSe detectors. This work is a major step towards Si-based mid-infrared photodetectors for imaging applications.
关键词： surface passivation,GeSn photodetector,high Sn composition,imaging,mid-infrared
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Mid-Infrared Silicon Waveguide-Based Bolometer
摘要： We demonstrate the ?rst waveguide-based bolometers on Silicon-on-Insulator (SOI) platform for mid-infrared (MIR) wavelengths, which use plasmonic antennas as absorbing elements. The bolometer achieves a sensitivity of 0.80 % change in resistance per milliwatt of input power at the 3.8 μm wavelength.
关键词： mid-infrared,silicon photonics,bolometer,optical antenna
更新于2025-09-16 10:30:52
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Lipid Droplet Composition Varies Based on Medaka Fish Eggs Development as Revealed by NIR-, MIR-, and Raman Imaging
摘要： In fertilized fish eggs, lipids are an energy reservoir for the embryo development and substrate for organogenesis. They occur in the cytoplasmic area and form lipid droplets (LDs), but also the yolk egg is composed of lipids and proteins. Insight on the LD formation and distribution and their interactions with other cellular organelles could provide information about the role based on the egg development. For non-destructive, macro-scale visualization of biochemical components of fish eggs, such as lipids proteins and water, near-infrared (NIR) imaging is the method of choice. Mid-infrared (MIR) and Raman spectroscopy imaging were used to provide details on chemical composition of LDs and other egg organelles. NIR imaging illustrated main compartments of the egg including membrane, LDs, yolk, relative protein, and lipid content in well-localized egg structures and their interactions with water molecules. In the yolk, a co-existence of lipids and proteins with carotenoids and carbohydrates was detected by Raman spectroscopy. Results showed a prominent decrease of unsaturated fatty acids, phospholipids, and triglycerides/cholesteryl esters content in the eggs due to the embryo development. An opposite trend of changes was observed by MIR spectroscopy for the glycogen, suggesting that consumption of lipids occurred with production of this carbohydrate. The comprehensive vibrational spectroscopic analysis based on NIR, MIR, and Raman imaging is a unique tool in studying in situ dynamic biological processes.
关键词： near- and mid-infrared spectroscopic imaging,Raman spectroscopic imaging,lipids,lipid bodies,fertilized egg
更新于2025-09-16 10:30:52
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Quantitative measurements of formaldehyde in the low-temperature oxidation of iso-octane using mid-infrared absorption spectroscopy
摘要： Time-resolved quantitative measurements of formaldehyde (HCHO) in the low-temperature oxidation of iso-octane using a rapid compression machine have been performed with mid-infrared laser absorption spectroscopy. Due to the weak interference of the broadband absorption of iso-octane, a two-color detection scheme was applied to HCHO detection. The cross-sections of HCHO and iso-octane in two colors were measured using the rapid compression machine in the temperature range of 450–737 K and pressure range of 100–700 kPa. The time-resolved quantitative HCHO profiles in the low-temperature oxidation of iso-octane at 0.77 MPa, 645 K, and an equivalence ratio of 1.0 were successfully obtained. The calculated HCHO profiles using the latest chemical kinetic model of iso-octane show the same tendency as the experimental profiles.
关键词： formaldehyde,mid-infrared absorption spectroscopy,iso-octane,low-temperature oxidation,rapid compression machine
更新于2025-09-16 10:30:52
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Analysis of Si3N4 waveguides for on-chip gas sensing by optical absorption within the mid-infrared region between 2.7 and 3.4???μm
摘要： We theoretically investigated the use of a Si3N4 on SiO2 waveguide as an optical interaction part with sensed molecules for multi-gas wideband on-chip spectroscopic sensing. From the analysis, we show that a simple strip Si3N4 waveguide can be employed to achieve acceptable values of performance in term of detection limit, compactness, polarization, and fabrication tolerance for the detection of water vapor (H2O), carbon dioxide (CO2), Nitrous oxide (N2O), Ammonia (NH3), Ethylene (C2H4), and Methane (CH4) gas molecules, with a wideband operation between 2.7 and 3.4 μm optical wavelength. The results show that a simple Si3N4 waveguide structure could attain competitive performance required for generic on-chip spectroscopic sensing for environmental and agricultural usage.
关键词： gas sensing,optical absorption,mid-infrared,on-chip spectroscopic sensing,Si3N4 waveguide
更新于2025-09-16 10:30:52
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[ACS Symposium Series] Fundamentals and Applications of Phosphorus Nanomaterials Volume 1333 || Black Phosphorus Based Photodetectors
摘要： The layered two-dimensional (2D) black phosphorus (BP) has found significant applications in nanoelectronics and nanophotonics. In particular, it has been proven as a promising material for photodetectors due to its narrow direct bandgap ranging from 0.3 eV to 2 eV, high carrier mobility, modulation capability, and polarization sensitivity. The modulation capability of BP based photodetector is achieved by gate control using field effect transistor structure. Homojunction and heterojunction have been demonstrated to suppress dark current while enhancing carrier collection efficiency. Plasmonic effect and avalanche breakdown are exploited to boost the responsivity further. To extend the detection wavelength of BP, electric field modulation and arsenide doping are investigated, leading to a wide detection wavelength up to 8 μm. Owing to the ease of integrating BP with diverse substrates due to BP’s 2D nature, waveguide-integrated BP based photodetectors are realized in the near-infrared (NIR) for telecommnunication applications and in the mid-infrared (MIR) for on-chip sensing applications. High speed and high responsivity can be achieved by optimizing the device design. Despite that the mechanical robustness of BP on waveguide remains challenging, nevertheless, wafer-level growth of BP is highly desirable to realize scalable integration for mass production.
关键词： near-infrared,black phosphorus,waveguide-integrated,nanoelectronics,nanophotonics,photodetectors,mid-infrared
更新于2025-09-12 10:27:22