A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based cryst...A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based crystal as Q-switcher,we obtained a laser diode(LD)end-pumped Er:CaF_(2)laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power.The implication of these results is that the low-doped Er:CaF_(2)crystal exhibits promising optical properties in solid-state lasers.展开更多
Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This st...Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.展开更多
With the development of mid-infrared (MIR) photoelectric devices, mid-infrared spectroscopy has become one of the important methods for non-invasive detection of blood glucose. The mid-infrared region (4000 - 400 cm&l...With the development of mid-infrared (MIR) photoelectric devices, mid-infrared spectroscopy has become one of the important methods for non-invasive detection of blood glucose. The mid-infrared region (4000 - 400 cm<sup>-1</sup>) has the well-known fingerprint region (1200 - 800 cm<sup>-1</sup>) of glucose, which has clearer characteristic absorption peaks and better specificity. There is a lot of molecular information about glucose in the MIR. The non-invasive detection of blood glucose by mid-infrared spectroscopy needs to achieve certain accuracy, and the quantitative model is an important factor affecting the accuracy of glucose detection. In this paper, the samples of imitation solution containing only glucose and the samples of imitation mixed solution are taken as the research objects, and the mid-infrared spectral data of the samples are collected. The full spectrum partial least squares Regression (PLSR) model, SNV + Ctr-PLSR model, MSC + Ctr-PLSR model, and convolutional neural networks (CNN) model of 3000 - 900 cm<sup>-1</sup> band were constructed. Full spectrum PLS model and CNN model of 1200 - 900 cm<sup>-1</sup> band were constructed. The experimental results show that the optimal model of the two bands is CNN, then the correlation coefficient of prediction set (Rp) of 3000 - 900 cm<sup>-1</sup> band is 0.95, and the root mean square error of pre-diction set (RMSEP) value is 22.10. The Rp of 1200 - 900 cm<sup>-1</sup> band is 0.95, and the RMSEP value is 22.54. The research results show that CNN is a promising method, which has higher accuracy than PLSR, and is especially suitable for modeling human complex environment. In addition, the study provides a theoretical and practical basis for CNN in feature selection and model interpretation.展开更多
In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution witho...In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution without two-beam interference(TBI).Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth.Consequently,during reconstruction,high lateral and axial resolutions are obtained.Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications.In this study,a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated.A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept.We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging,fluorescence microscopy,mid-infrared fingerprinting,astronomical imaging,and fast object recognition applications.展开更多
Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings...Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings,and camouflage.The ability to control light makes metasurfaces an attractive platform for infrared applications.Recently,different metamaterials have been proposed to achieve high thermal radiation.To date,broadening the radiation bandwidth of a metasurface emitter(meta-emitter)has become a key goal to enable extensive applications.We experimentally demonstrate a broadband M-IR thermal emitter using stacked nanocavity metasurface consisting of two pairs of circular-shaped dielectric(Si;N;)–metal(Au)stacks.A high thermal radiation can be obtained by engineering the geometry of nanocavity metasurfaces.Such a meta-emitter provides wideband and broad angular absorptance of both p-and s-polarized light,offering a wideband thermal radiation with an average emissivity of more than 80%in the M-IR atmospheric window of 8–14μm.The experimental illustration together with the theoretical framework establishes a basis for designing broadband thermal emitters,which,as anticipated,will initiate a promising avenue to M-IR sources.展开更多
InGaSb/AlGaAsSb double-quantum-well diode lasers emitting around 2 μm are demonstrated. The AlGaAsSb barriers of the lasers are grown with digital alloy techniques consisting of binary AlSb/AlAs/GaSb short-period pai...InGaSb/AlGaAsSb double-quantum-well diode lasers emitting around 2 μm are demonstrated. The AlGaAsSb barriers of the lasers are grown with digital alloy techniques consisting of binary AlSb/AlAs/GaSb short-period pairs. Peak power conversion efficiency of 26% and an efficiency higher than 16% at 1 W are achieved at continuous-wave operation for a 2-mm-long and 100-μm-wide stripe laser. The maximum output power of a single emitter reaches to 1.4 W at 7 A.19-emitter bars with maximum efficiency higher than 20% and maximum power of 16 W are fabricated. Lasers with the short-period-pair barriers are proved to have improved temperature properties and wavelength stabilities. The characteristic temperature(T_0) is up to 140?C near room temperature(25–55?C).展开更多
We report on a chalcogenide glass fiber doped with Pr^(3+) that can be used for commercialized 1.5-μm and 2-μm laser excitations by emitting broadband 3 μm–5.5 μm fluorescence, which is extruded into a preform an...We report on a chalcogenide glass fiber doped with Pr^(3+) that can be used for commercialized 1.5-μm and 2-μm laser excitations by emitting broadband 3 μm–5.5 μm fluorescence, which is extruded into a preform and then drawn into a step-index fiber. The spectroscopic properties of the fiber and glass are reported, and the mid-infrared fiber lasers are also numerically investigated. Cascade lasing is employed to increase the inversion population of the upper laser level. The particle swarm approach is applied to optimize the fiber laser parameters. The output power can reach 1.28 W at 4.89-μm wavelength, with a pump power of 5 W, excitation wavelength at 2.04 μm, Pr^(3+) ion concentration at 4.22 × 10^(25) ions/m^3,fiber length at 0.94 m, and fiber background loss at 3 dB/m.展开更多
Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically...Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically. The simulation results show that when the parabolic pulse is input, not only broader and higher-coherence SCG is obtained and a higher effective number of bits(ENOB) can be achieved, compared with the input pulse with hyperbolic-secant and Gaussian shaping. A four-bit quantization resolution is achieved along with a signal-to-noise ratio of 24.02 dB and an ENOB of3.99 bit, and the required input peak power is 760 mW.展开更多
We reported an ultrabroadband mid-infrared(MIR)emission in the range of 1800 nm-3100 nm at room temperature(RT)from a Cr^(2+):ZnSe-doped chalcogenide glasses(ChGs)and studied the emission-dependent properties on the d...We reported an ultrabroadband mid-infrared(MIR)emission in the range of 1800 nm-3100 nm at room temperature(RT)from a Cr^(2+):ZnSe-doped chalcogenide glasses(ChGs)and studied the emission-dependent properties on the doping methods.A series of Cr^(2+):ZnSe/As_(40)S_(57)Se_(3)(in unit wt.%)glass-ceramics were prepared by hot uniaxial pressing(HUP)and melt-quenching methods,respectively.The glass-ceramics with MIR emission bands greater than 1000 nm were successfully prepared by both methods.The effects of matrix glass composition and grain doping concentration on the optical properties of the samples were studied.The occurrence state,morphology of the grains,and the microscopic elemental distributions were characterized using x-ray diffraction(XRD),scanning electron microscope(SEM),and energy dispersive spectrometer(EDS)analyses.展开更多
Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light c...Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.展开更多
Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-l...Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-low concentration gas detection,technical bottlenecks of MOFs appear due to the poor adsorption capacity at ppm-/ppblevel concentration and the limited sensitivity for signal transduction.Here,we present hybrid MOF-polymer physi-chemisorption mechanisms integrated with infrared(IR)nanoantennas for highly selective and ultrasensitive CO_(2) detection.To improve the adsorption capacity for trace amounts of gas molecules,MOFs are decorated with amino groups to introduce the chemisorption while maintaining the structural integrity for physisorption.Additionally,leveraging all major optimization methods,a multi-hotspot strategy is proposed to improve the sensitivity of nanoantennas by enhancing the near field and engineering the radiative and absorptive loss.As a benefit,we demonstrate the competitive advantages of our strategy against the state-of-the-art miniaturized IR CO_(2) sensors,including low detection limit,high sensitivity(0.18%/ppm),excellent reversibility(variation within 2%),and high selectivity(against C_(2)H_(5)OH,CH_(3)OH,N_(2)).This work provides valuable insights into the integration of advanced porous materials and nanophotonic devices,which can be further adopted in ultra-low concentration gas monitoring in industry and environmental applications.展开更多
Narrow band mid-infrared(MIR)absorption is highly desired in thermal emitter and sensing applications.We theoretically demonstrate that the perfect absorption at infrared frequencies can be achieved and controlled aro...Narrow band mid-infrared(MIR)absorption is highly desired in thermal emitter and sensing applications.We theoretically demonstrate that the perfect absorption at infrared frequencies can be achieved and controlled around the surface phonon resonance frequency of silicon carbide(SiC).The photonic heterostructure is composed of a distributed Bragg reflector(DBR)/germanium(Ge)cavity/SiC on top of a Ge substrate.Full-wave simulation results illustrate that the Tamm phonon-polaritons electric field can locally concentrate between the Ge cavity and the SiC film,contributed to the improved light-phonon interactions with an enhancement of light absorption.The structure has planar geometry and does not require nano-patterning to achieve perfect absorption of both polarizations of the incident light in a wide range of incident angles.Their absorption lines are tunable via engineering of the photon band-structure of the dielectric photonic nanostructures to achieve reversal of the geometrical phase across the interface with the plasmonic absorber.展开更多
Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)...Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)was applied to seek sparse factors of the mid-infrared(MIR)spectra of five famous vintage year Chinese spirits.The results showed while meeting the maximum explained variance,23 sparse principal components(PCs)were selected as features in a support vector machine(SVM)model,which obtained a 97%classification accuracy.By comparison principal component analysis(PCA)selected 10 PCs as features but only achieved an 83%classification accuracy.Although both approaches were better than a direct SVM approach based on the classification results(64%classification accuracy),they also demonstrated the importance of extracting sparse PCs,which captured most important information.The combination of computer technology SPCA and MIR provides a new and convenient method for liquor identification in food safety.展开更多
We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite ph...We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite photonic crystal fiber(MM-TPCF).The geometrical parameters of the MM-TPCF are optimized to support the multimode propagation and obtain the desired dispersion characteristics of the considered three optical modes.When the pump pulse with center wavelengthλ=2.5μm,width T=80 fs,and peak power P=18 kW is coupled into the anomalous dispersion region of the LP_(01),LP_(02),and LP_(12)modes of the MM-TPCF,the-40-dB bandwidth of the generated MIR SCs can be up to 2.56,1.39,and 1.12 octaves,respectively,along with good coherence.Moreover,the nonlinear dynamics of the generated SCs are analyzed.Finally,the MIR SCs-based OFCs are demonstrated when a train of 50 pulses at 1-GHz repetition rate is used as the pump source and launched into the MM-TPCF.展开更多
We demonstrated the~2.8-μm and~3.5-μm linearly polarized continuous wave(CW)laser outputs from a polarization-maintaining(PM)Er^(3+)-doped fluoride fiber laser.By introducing a film polarizer into the cavity to sele...We demonstrated the~2.8-μm and~3.5-μm linearly polarized continuous wave(CW)laser outputs from a polarization-maintaining(PM)Er^(3+)-doped fluoride fiber laser.By introducing a film polarizer into the cavity to select the laser polarization orientation,the~2.8-μm linearly polarized CW laser with a high polarization extinction ratio(PER)of~23 dB and maximum output power of 2.37 W was achieved under double-end pumping at 976 nm.By adding another 1981-nm pump source simultaneously,the~3.5-μm linearly polarized CW laser was also obtained,giving higher PER of~27 dB and maximum output power of 307 mW which is only limited by the available power of 1981-nm pump.To the best of our knowledge,this is the first report on a mid-infrared linearly polarized CW PM fiber laser in the>2.5-μm mid-infrared region.This work not only opens up opportunities for some new mid-infrared applications,but also provides a promising platform for developing high-stability and versatile mid-infrared laser sources.展开更多
This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,t...This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,this paper draws a conclusion that IR has several advantages,including rapid analysis,excellent repeatability and low analysis cost.展开更多
The mid infrared regime is little affected by extinction, and it contains a plethora of spectroscopic information. The Infrared Space Observatory (ISO) has provided access to this wealth of information. Here I present...The mid infrared regime is little affected by extinction, and it contains a plethora of spectroscopic information. The Infrared Space Observatory (ISO) has provided access to this wealth of information. Here I present new results from a study of ISO SWS spectra of about 30 AGNs, concentrating on diagnostic digrams to distinguish between star formation and AGNs as energy source in dusty galaxies (such as ULIRGs), and to discuss the Starburst AGN connection in general. Further results and all details of this study can be found in Sturm et al. (2002).展开更多
Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spect...Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser;lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.展开更多
基金the National Natural Science Foundation of China(Grant Nos.11974220,61925508,61905265,and 12104271)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2021LLZ008 and ZR2021QA030)+1 种基金the Fund from Science and Technology Commission of Shanghai Municipality(Grant No.20511107400)CAS Interdisciplinary Innovation Team(Grant No.JCTD-2019-12).
文摘A 1.7-at.%Er:CaF_(2)crystal was synthesized by temperature gradient method.The Er:CaF_(2)crystal was applied in acousto-optically Q-switched laser at mid-infrared region for the first time.Using a Te O_(2)-based crystal as Q-switcher,we obtained a laser diode(LD)end-pumped Er:CaF_(2)laser with the highest single pulse energy up to 0.49 mJ and maximum peak power of 0.56 kW under 6.34-W absorbed pump power.The implication of these results is that the low-doped Er:CaF_(2)crystal exhibits promising optical properties in solid-state lasers.
文摘Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.
文摘With the development of mid-infrared (MIR) photoelectric devices, mid-infrared spectroscopy has become one of the important methods for non-invasive detection of blood glucose. The mid-infrared region (4000 - 400 cm<sup>-1</sup>) has the well-known fingerprint region (1200 - 800 cm<sup>-1</sup>) of glucose, which has clearer characteristic absorption peaks and better specificity. There is a lot of molecular information about glucose in the MIR. The non-invasive detection of blood glucose by mid-infrared spectroscopy needs to achieve certain accuracy, and the quantitative model is an important factor affecting the accuracy of glucose detection. In this paper, the samples of imitation solution containing only glucose and the samples of imitation mixed solution are taken as the research objects, and the mid-infrared spectral data of the samples are collected. The full spectrum partial least squares Regression (PLSR) model, SNV + Ctr-PLSR model, MSC + Ctr-PLSR model, and convolutional neural networks (CNN) model of 3000 - 900 cm<sup>-1</sup> band were constructed. Full spectrum PLS model and CNN model of 1200 - 900 cm<sup>-1</sup> band were constructed. The experimental results show that the optimal model of the two bands is CNN, then the correlation coefficient of prediction set (Rp) of 3000 - 900 cm<sup>-1</sup> band is 0.95, and the root mean square error of pre-diction set (RMSEP) value is 22.10. The Rp of 1200 - 900 cm<sup>-1</sup> band is 0.95, and the RMSEP value is 22.54. The research results show that CNN is a promising method, which has higher accuracy than PLSR, and is especially suitable for modeling human complex environment. In addition, the study provides a theoretical and practical basis for CNN in feature selection and model interpretation.
基金European Union’s Horizon 2020 research and innovation programme under grant agreement No.857627(CIPHR).
文摘In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution without two-beam interference(TBI).Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth.Consequently,during reconstruction,high lateral and axial resolutions are obtained.Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications.In this study,a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated.A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept.We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging,fluorescence microscopy,mid-infrared fingerprinting,astronomical imaging,and fast object recognition applications.
基金support from the National Key Research and Development Program of China(2019YFA0709100,2020YFA0714504)Fundamental Research Funds for the Central Universities(Nos.DUT20GF108,DUT20RC(3)007,DUT20RC(3)062,DUT19RC(3)010)the Program for Liaoning excellent Talents in University(Grant No.LJQ2015021)。
文摘Efficient thermal radiation in the mid-infrared(M-IR)region is of supreme importance for many applications including thermal imaging and sensing,thermal infrared light sources,infrared spectroscopy,emissivity coatings,and camouflage.The ability to control light makes metasurfaces an attractive platform for infrared applications.Recently,different metamaterials have been proposed to achieve high thermal radiation.To date,broadening the radiation bandwidth of a metasurface emitter(meta-emitter)has become a key goal to enable extensive applications.We experimentally demonstrate a broadband M-IR thermal emitter using stacked nanocavity metasurface consisting of two pairs of circular-shaped dielectric(Si;N;)–metal(Au)stacks.A high thermal radiation can be obtained by engineering the geometry of nanocavity metasurfaces.Such a meta-emitter provides wideband and broad angular absorptance of both p-and s-polarized light,offering a wideband thermal radiation with an average emissivity of more than 80%in the M-IR atmospheric window of 8–14μm.The experimental illustration together with the theoretical framework establishes a basis for designing broadband thermal emitters,which,as anticipated,will initiate a promising avenue to M-IR sources.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61790580 and 61435012)the National Basic Research Program of China(Grant No.2014CB643903)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.YJKYYQ20170032)
文摘InGaSb/AlGaAsSb double-quantum-well diode lasers emitting around 2 μm are demonstrated. The AlGaAsSb barriers of the lasers are grown with digital alloy techniques consisting of binary AlSb/AlAs/GaSb short-period pairs. Peak power conversion efficiency of 26% and an efficiency higher than 16% at 1 W are achieved at continuous-wave operation for a 2-mm-long and 100-μm-wide stripe laser. The maximum output power of a single emitter reaches to 1.4 W at 7 A.19-emitter bars with maximum efficiency higher than 20% and maximum power of 16 W are fabricated. Lasers with the short-period-pair barriers are proved to have improved temperature properties and wavelength stabilities. The characteristic temperature(T_0) is up to 140?C near room temperature(25–55?C).
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61605095)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY19F050004)+2 种基金the Natural Science Foundation of Ningbo City(Grant No.2015A610038)the Open Fund of the Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices(South China University of Technology)(Grant No.2016-4)the K C Wong Magna Fund at Ningbo University
文摘We report on a chalcogenide glass fiber doped with Pr^(3+) that can be used for commercialized 1.5-μm and 2-μm laser excitations by emitting broadband 3 μm–5.5 μm fluorescence, which is extruded into a preform and then drawn into a step-index fiber. The spectroscopic properties of the fiber and glass are reported, and the mid-infrared fiber lasers are also numerically investigated. Cascade lasing is employed to increase the inversion population of the upper laser level. The particle swarm approach is applied to optimize the fiber laser parameters. The output power can reach 1.28 W at 4.89-μm wavelength, with a pump power of 5 W, excitation wavelength at 2.04 μm, Pr^(3+) ion concentration at 4.22 × 10^(25) ions/m^3,fiber length at 0.94 m, and fiber background loss at 3 dB/m.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61307109 and 61475023)
文摘Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically. The simulation results show that when the parabolic pulse is input, not only broader and higher-coherence SCG is obtained and a higher effective number of bits(ENOB) can be achieved, compared with the input pulse with hyperbolic-secant and Gaussian shaping. A four-bit quantization resolution is achieved along with a signal-to-noise ratio of 24.02 dB and an ENOB of3.99 bit, and the required input peak power is 760 mW.
基金Project supported by the Key Research and Development Program of Zhejiang Province,China (Grant No. 2021C01025)the National Natural Science Foundation of China (Grant Nos. 61975086 and 61605095)+3 种基金the Zhejiang Provincial Natural Science Foundation of China (Grant No. LY19F050004)the National Key Research and Development Program of China (Grant No. 2016YFB0303803)the K. C. Wong Magna Fund at Ningbo Universitythe Natural Science Foundation of Ningbo (Grant No. 202003N4180)
文摘We reported an ultrabroadband mid-infrared(MIR)emission in the range of 1800 nm-3100 nm at room temperature(RT)from a Cr^(2+):ZnSe-doped chalcogenide glasses(ChGs)and studied the emission-dependent properties on the doping methods.A series of Cr^(2+):ZnSe/As_(40)S_(57)Se_(3)(in unit wt.%)glass-ceramics were prepared by hot uniaxial pressing(HUP)and melt-quenching methods,respectively.The glass-ceramics with MIR emission bands greater than 1000 nm were successfully prepared by both methods.The effects of matrix glass composition and grain doping concentration on the optical properties of the samples were studied.The occurrence state,morphology of the grains,and the microscopic elemental distributions were characterized using x-ray diffraction(XRD),scanning electron microscope(SEM),and energy dispersive spectrometer(EDS)analyses.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065101 and 11934013)Anhui Initiative In Quantum Information Technologies (Grant No. AHY020200)。
文摘Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.
基金This work is supported by the RIE Advanced Manufacturing and Engineering(AME)Programmatic Grant Project(Grant A18A5b0056,WBS:A-0005117-02-00)the Advanced Research and Technology Innovation Centre(ARTIC)Project(WBS:A-0005947-20-00)the Ministry of Education(MOE)of Singapore Tier 1 Project(WBS:A-0005138-01-00).
文摘Metal-organic frameworks(MOFs)have been extensively used for gas sorption,storage and separation owing to ultrahigh porosity,exceptional thermal stability,and wide structural diversity.However,when it comes to ultra-low concentration gas detection,technical bottlenecks of MOFs appear due to the poor adsorption capacity at ppm-/ppblevel concentration and the limited sensitivity for signal transduction.Here,we present hybrid MOF-polymer physi-chemisorption mechanisms integrated with infrared(IR)nanoantennas for highly selective and ultrasensitive CO_(2) detection.To improve the adsorption capacity for trace amounts of gas molecules,MOFs are decorated with amino groups to introduce the chemisorption while maintaining the structural integrity for physisorption.Additionally,leveraging all major optimization methods,a multi-hotspot strategy is proposed to improve the sensitivity of nanoantennas by enhancing the near field and engineering the radiative and absorptive loss.As a benefit,we demonstrate the competitive advantages of our strategy against the state-of-the-art miniaturized IR CO_(2) sensors,including low detection limit,high sensitivity(0.18%/ppm),excellent reversibility(variation within 2%),and high selectivity(against C_(2)H_(5)OH,CH_(3)OH,N_(2)).This work provides valuable insights into the integration of advanced porous materials and nanophotonic devices,which can be further adopted in ultra-low concentration gas monitoring in industry and environmental applications.
基金Project supported by the National Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20191396,BK20180784).
文摘Narrow band mid-infrared(MIR)absorption is highly desired in thermal emitter and sensing applications.We theoretically demonstrate that the perfect absorption at infrared frequencies can be achieved and controlled around the surface phonon resonance frequency of silicon carbide(SiC).The photonic heterostructure is composed of a distributed Bragg reflector(DBR)/germanium(Ge)cavity/SiC on top of a Ge substrate.Full-wave simulation results illustrate that the Tamm phonon-polaritons electric field can locally concentrate between the Ge cavity and the SiC film,contributed to the improved light-phonon interactions with an enhancement of light absorption.The structure has planar geometry and does not require nano-patterning to achieve perfect absorption of both polarizations of the incident light in a wide range of incident angles.Their absorption lines are tunable via engineering of the photon band-structure of the dielectric photonic nanostructures to achieve reversal of the geometrical phase across the interface with the plasmonic absorber.
基金This work was financially supported by the National Nature Science Foundation of China(Grant Number:61962010).
文摘Applying computer technology to the field of food safety,and how to identify liquor quickly and accurately,is of vital importance and has become a research focus.In this paper,sparse principal component analysis(SPCA)was applied to seek sparse factors of the mid-infrared(MIR)spectra of five famous vintage year Chinese spirits.The results showed while meeting the maximum explained variance,23 sparse principal components(PCs)were selected as features in a support vector machine(SVM)model,which obtained a 97%classification accuracy.By comparison principal component analysis(PCA)selected 10 PCs as features but only achieved an 83%classification accuracy.Although both approaches were better than a direct SVM approach based on the classification results(64%classification accuracy),they also demonstrated the importance of extracting sparse PCs,which captured most important information.The combination of computer technology SPCA and MIR provides a new and convenient method for liquor identification in food safety.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074331,61875238,and 61971373)the Natural Science Foundation of Hebei Province,China(Grant Nos.F2021203002,F2019203549,and F2020203050)the Science and Technology Support Projects of Research and Development Plans of Qinhuangdao City(Grant No.202004A001).
文摘We numerically investigate the mid-infrared(MIR)supercontinuum(SC)and SC-based optical frequency comb(OFC)generations when the three optical modes(LP_(01),LP_(02),and LP_(12))are considered in a multimode tellurite photonic crystal fiber(MM-TPCF).The geometrical parameters of the MM-TPCF are optimized to support the multimode propagation and obtain the desired dispersion characteristics of the considered three optical modes.When the pump pulse with center wavelengthλ=2.5μm,width T=80 fs,and peak power P=18 kW is coupled into the anomalous dispersion region of the LP_(01),LP_(02),and LP_(12)modes of the MM-TPCF,the-40-dB bandwidth of the generated MIR SCs can be up to 2.56,1.39,and 1.12 octaves,respectively,along with good coherence.Moreover,the nonlinear dynamics of the generated SCs are analyzed.Finally,the MIR SCs-based OFCs are demonstrated when a train of 50 pulses at 1-GHz repetition rate is used as the pump source and launched into the MM-TPCF.
基金supported by the National Natural Science Foundation of China under Grant No.62005040the Fundamental Research Funds for the Central Universities under Grant No.ZYGX2020KYQD003the Science and Technology Project of Sichuan Province under Grant No.2021YJ0368.
文摘We demonstrated the~2.8-μm and~3.5-μm linearly polarized continuous wave(CW)laser outputs from a polarization-maintaining(PM)Er^(3+)-doped fluoride fiber laser.By introducing a film polarizer into the cavity to select the laser polarization orientation,the~2.8-μm linearly polarized CW laser with a high polarization extinction ratio(PER)of~23 dB and maximum output power of 2.37 W was achieved under double-end pumping at 976 nm.By adding another 1981-nm pump source simultaneously,the~3.5-μm linearly polarized CW laser was also obtained,giving higher PER of~27 dB and maximum output power of 307 mW which is only limited by the available power of 1981-nm pump.To the best of our knowledge,this is the first report on a mid-infrared linearly polarized CW PM fiber laser in the>2.5-μm mid-infrared region.This work not only opens up opportunities for some new mid-infrared applications,but also provides a promising platform for developing high-stability and versatile mid-infrared laser sources.
文摘This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,this paper draws a conclusion that IR has several advantages,including rapid analysis,excellent repeatability and low analysis cost.
文摘The mid infrared regime is little affected by extinction, and it contains a plethora of spectroscopic information. The Infrared Space Observatory (ISO) has provided access to this wealth of information. Here I present new results from a study of ISO SWS spectra of about 30 AGNs, concentrating on diagnostic digrams to distinguish between star formation and AGNs as energy source in dusty galaxies (such as ULIRGs), and to discuss the Starburst AGN connection in general. Further results and all details of this study can be found in Sturm et al. (2002).
文摘Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser;lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.
