- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Mid infrared gas spectroscopy using efficient fiber laser driven photonic chip-based supercontinuum
摘要： Directly accessing the middle infrared, the molecular functional group spectral region, via supercontinuum generation processes based on turn-key fiber lasers offers the undeniable advantage of simplicity and robustness. Recently, the assessment of the coherence of the mid-IR dispersive wave in silicon nitride (Si3N4) waveguides, pumped at telecom wavelength, established an important first step towards mid-IR frequency comb generation based on such compact systems. Yet, the spectral reach and efficiency still fall short for practical implementation. Here, we experimentally demonstrate that large cross-section Si3N4 waveguides pumped with 2 μm fs-fiber laser can reach the important spectroscopic spectral region in the 3–4 μm range, with up to 35% power conversion and milliwatt-level output powers. As a proof of principle, we use this source for detection of C2H2 by absorption spectroscopy. Such result makes these sources suitable candidate for compact, chip-integrated spectroscopic and sensing applications.
关键词： mid infrared,photonic chip,gas spectroscopy,supercontinuum generation,fiber laser
更新于2025-11-28 14:23:57
-
Open-path Halon 1301 NDIR sensor with temperature compensation
摘要： Halon 1301 (bromotrifluoromethane) is a kind of fire extinguishing agent in aviation industry. Volume concentration measurement of Halon 1301 is necessary in the design of aircraft fire protection systems. In this research, an open-path Halon 1301 non-dispersive infrared (NDIR) sensor has been developed for in-situ measurement, a novel cavity-type absorption module was designed to get fast response and more compact structure. Experiment results show that measurement was remarkably affected by temperature. Therefore, temperature compensation algorithm was also studied in this thesis, which was proven to be effective within the range of 25 oC-105 oC.
关键词： non-dispersive infrared (NDIR),mid-infrared absorption spectrum,Halon 1301,temperature compensation,concentration measurement
更新于2025-09-23 15:23:52
-
High-temperature mid-infrared absorption spectra of methanol (CH3OH) and ethanol (C2H5OH) between 930 and 1170?cm-1
摘要： A methodology was recently developed with a broad-tuning, rapid-scan external-cavity quantum-cascade-laser in conjunction with shock tube facilities to measure the high-temperature mid-infrared absorption spectra of gaseous molecules. This technique is deployed to measure the cross section profiles in the C-O stretching band for methanol (CH3OH) and ethanol (C2H5OH) between 930 and 1170 cm-1. Methanol spectra are presented from 620 to 1304K between 0.98-3.30 atm with distinctive P, Q, and R branches of the ν8 vibrational band. At elevated temperatures, the emergence of hotbands and high-J ro-vibrational transitions are clearly observed. The absorption cross sections of ethanol are measured from 296 to 1018K between 0.90-3.27 atm. The peak strength decreases with temperature, with the peak location shifting to lower wavenumbers. These measurements are compared with existing empirical models, illustrating a strong need for the development of a high-temperature spectroscopic database.
关键词： Absorption spectra,Ethanol,Mid-infrared,High-temperature,Shock tube,Methanol
更新于2025-09-23 15:23:52
-
Deeply subwavelength phonon-polaritonic crystal made of a van der Waals material
摘要： Photonic crystals (PCs) are periodically patterned dielectrics providing opportunities to shape and slow down the light for processing of optical signals, lasing and spontaneous emission control. Unit cells of conventional PCs are comparable to the wavelength of light and are not suitable for subwavelength scale applications. We engineer a nanoscale hole array in a van der Waals material (h-BN) supporting ultra-confined phonon polaritons (PhPs)—atomic lattice vibrations coupled to electromagnetic fields. Such a hole array represents a polaritonic crystal for mid-infrared frequencies having a unit cell volume of 10??λ?3 (with λ? being the free-space wavelength), where PhPs form ultra-confined Bloch modes with a remarkably flat dispersion band. The latter leads to both angle- and polarization-independent sharp Bragg resonances, as verified by far-field spectroscopy and near-field optical microscopy. Our findings could lead to novel miniaturized angle- and polarization-independent infrared narrow-band couplers, absorbers and thermal emitters based on van der Waals materials and other thin polar materials.
关键词： van der Waals material,near-field microscopy,phonon-polaritonic crystal,mid-infrared,hexagonal boron nitride,Bragg resonance
更新于2025-09-23 15:23:52
-
Fabrication and mid-infrared property of Er:CaF2 transparent ceramics
摘要： High doped Er:CaF2 transparent ceramics (up to 10.0 at.%) were fabricated by hot pressing nanopowders which were synthesized by co-precipitation method. The composition and micrographs of the powders were characterized. The mid-infrared emission spectra and lifetimes of the 4I13/2 energy level of Er:CaF2 transparent ceramics were investigated for the first time. The mechanisms of energy transfer processes based on the emission spectra of different wavelengths were discussed. The enhanced 2.7 μm emission intensity and the reductions of near-infrared fluorescence lifetimes were observed indicating that the high concentrations of Er3+ ions are beneficial to overcome the self-termination effect and realize 2.7 μm laser output. It can be seen from these results that high concentrations Er-doped CaF2 transparent ceramics can be considered as promising host materials for the applications of mid-infrared lasers.
关键词： Transparent ceramic,Mid-infrared,Luminescence lifetime,Nanoparticle
更新于2025-09-23 15:23:52
-
2.01～ 2.42 μm all-fiber femtosecond Raman soliton generation in a heavily germanium doped fiber
摘要： We demonstrated that an all-fiber system generates high-performance mid-infrared Raman solitons in a heavily germanium doped fiber (HGDF). A 10 m-long HGDF with a 12 μm core diameter and 64 mol.% GeO2 dopant is designed and pumped by a home-made 1.96 μm femtosecond fiber laser in the strong anomalous dispersion region. Stable and single-color Raman solitons are therefore obtained with a continuous wavelength tunability from 2.01 to 2.42 μm. The pulse duration of the mid-infrared Raman solitons can be as short as ~220 fs. The efficiency of energy transfer to a Raman soliton is about 32.5%, while the maximum average power, peak power and pulse energy are up to 27 mW, 3.6 kW and ~1 nJ, respectively. Different from previous multi-color Raman or supercontinuum-like generation from HGDFs pumped in the near-zero or normal dispersion regime, such pure mid-infrared Raman solitons exhibit excellent stability with a radio-frequency signal-to-noise ratio of ~60 dB. This is, to the best of our knowledge, the first demonstration of >2.4 μm stable Raman solitons in an all-fiber system. This work may pave a path towards compact and high-performance mid-infrared femtosecond fiber laser sources.
关键词： soliton self-frequency shift,Ultrafast fiber lasers,heavily germanium doped fiber,mid-infrared
更新于2025-09-23 15:22:29
-
Generation of polarization-sensitive modulated optical vortices with all-dielectric metasurfaces
摘要： Optical vortices (OVs) created from helical modes of light have extensive applications in optical manipulation, imaging and optical communications. Moreover, modulated optical vortices (MOVs) with modified wavefronts could provide new opportunities for fractionating particles and actuating microelectromechanical systems. Traditional devices for generating MOVs include spatial light modulators, spiral phase plates etc. However, such bulky devices are difficult to be applied to high-level integrated optical systems. Besides, other MOV generators are typically static and polarization-insensitive. Here, we proposed an all-dielectric metasurface to generate polarization-sensitive MOVs. The intensity patterns of the OVs can be modulated by adding a tangential modulation factor in the phase profile. Independent manipulation of two orthogonal polarizations was adopted via tailoring the geometric parameters of silicon (Si) pillars. We experimentally demonstrated that the metasurface could generate a doughnut and an actinomorphic vortex beams for different polarization inputs. In addition, the intensity pattern of the MOVs can be dynamically tuned by adjusting the polarization angle. This work can benefit optical manipulation and can be further extended to visible and near-infrared bands.
关键词： propagation phase,all-dielectric metasurfaces,mid-infrared,polarizations,modulated optical vortices
更新于2025-09-23 15:22:29
-
Metabolic profiling of early lactation dairy cows using milk mid-infrared spectra
摘要： Metabolic disorders in early lactation have negative effects on dairy cow health and farm profitability. One method for monitoring the metabolic status of cows is metabolic profiling, which uses associations between the concentrations of several metabolites in serum and the presence of metabolic disorders. In this cross-sectional study, we investigated the use of mid-infrared (MIR) spectroscopy of milk for predicting the concentrations of these metabolites in serum. Between July and October 2017, serum samples were taken from 773 early-lactation Holstein Friesian cows located on 4 farms in the Gippsland region of south-eastern Victoria, Australia, on the same day as milk recording. The concentrations in sera of β-hydroxybutyrate (BHB), fatty acids, urea, Ca, Mg, albumin, and globulins were measured by a commercial diagnostic laboratory. Optimal concentration ranges for each of the 7 metabolites were obtained from the literature. Animals were classified as being either affected or unaffected with metabolic disturbances based on these ranges. Milk samples were analyzed by MIR spectroscopy. The relationships between serum metabolite concentrations and MIR spectra were investigated using partial least squares regression. Partial least squares discriminant analyses (PLS-DA) were used to classify animals as being affected or not affected with metabolic disorders. Calibration equations were constructed using data from a randomly selected subset of cows (n = 579). Data from the remaining cows (n = 194) were used for validation. The coefficient of determination (R2) of serum BHB, fatty acids, and urea predictions were 0.48, 0.61, and 0.90, respectively. Predictions of Ca, Mg, albumin, and globulin concentrations were poor (0.06 ≤ R2 ≤ 0.17). The PLS-DA models could predict elevated fatty acid and urea concentrations with an accuracy of approximately 77 and 94%, respectively. A second independent validation data set was assembled in March 2018, comprising blood and milk samples taken from 105 autumn-calving cows of various breeds. The accuracies of BHB and fatty acid predictions were similar to those obtained using the first validation data set. The PLS-DA results were difficult to interpret due to the low prevalence of metabolic disorders in the data set. Our results demonstrate that MIR spectroscopy of milk shows promise for predicting the concentration of BHB, fatty acids, and urea in serum; however, more data are needed to improve prediction accuracies.
关键词： mid-infrared spectral prediction,metabolic profile,energy balance,ketosis
更新于2025-09-23 15:22:29
-
Actively tunable mid-infrared Fano resonance in Ge2Sb2Te5-based grating structures
摘要： Dynamic tuning of the resonance wavelength of subwavelength gratings in the mid-infrared (MIR) region via the permittivity change of phase-change material (PCM) has been demonstrated. A large shift in the peak of reflectance can be obtained by intermediate phase states of the Ge2Sb2Te5 (GST) layer. Fano resonance (FR) can be excited and is verified by the rigorous coupled-wave analysis (RCWA) method. Non-volatile tuning of lattice resonances over a range Δλ of about 1.9 μm (10.9 μm–12.8 μm) is achieved. Significant spectral tuning of FR can also be achieved by changing geometrical parameters as well as the angle of incidence. The wide range of the tunable FR in the technologically important MIR region offers a high resolution filter, which is useful for numerous sensing, imaging, and detection applications.
关键词： Fano resonance,Phase change materials,Mid-infrared
更新于2025-09-23 15:22:29
-
Efficient cascaded wavelength conversion based on Stark-chirped rapid adiabatic passage
摘要： We demonstrate a highly efficient process of cascaded wavelength conversion among three states that is based on the Stark-chirped rapid adiabatic passage technique, and enables the achievement of nearly complete wavelength conversion in the mid-infrared laser generation process. By analyzing the relevant parameters in the model, we identify various factors that affect the efficiency of the conversion process. Compared with traditional cascaded wavelength conversion based on the technique of stimulated Raman adiabatic passage, the new conversion process not only maintains a high efficiency but also keeps the intermediate frequency strength low along the interacting length and achieves better stability when the relevant parameters change.
关键词： Stark-chirped rapid adiabatic passage,efficiency,cascaded wavelength conversion,stability,mid-infrared laser
更新于2025-09-23 15:22:29