Mid-infrared(MIR)-polarized thermal emission has broad applications in areas such as molecular sensing,information encryption,target detection,and optical communication.However,it is difficult for objects in nature to...Mid-infrared(MIR)-polarized thermal emission has broad applications in areas such as molecular sensing,information encryption,target detection,and optical communication.However,it is difficult for objects in nature to produce polarized thermal emission.Moreover,simultaneously generating and modulating broadband MIR thermal emission with both circular and linear polarization is even more difficult.We present a chiral plasmonic metasurface emitter(CPME)composed of asymmetric L-shaped and I-shaped antennas.The CPME consists of In_(3)SbTe_(2)(IST)phase-change material(PCM)antennas,an Al_(2)O_(3) dielectric layer,and an Au substrate.It is demonstrated that the CPME can selectively emit polarized light with different polarization states.Numerical simulations show that the CPME can achieve full Stokes parameter control of MIR thermal emission.By changing the state of the PCM IST,the spectral emissivity of 0 deg,45 deg,90 deg,and 135 deg linearly polarized(LP)lights and left-handed/right-handed circularly polarized(LCP/RCP)lights can be adjusted.In the crystalline state,the CPME exhibits the total degree of polarization(DoP)greater than 0.5 in the wavelength range of 3.4 to 5.3μm,the degree of linear polarization(DoLP)greater than 0.4 in the range of 3.0 to 5.1μm,and the degree of circular polarization(DoCP)greater than 0.4 in the range of 4.5 to 5.6μm.The physical mechanism of polarized emission has been investigated fully based on the near-field intensity distribution and power loss distribution.Finally,the potential applications of the designed CPME in infrared polarization detection and antidetection are verified through numerical calculations.展开更多
Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band lim...Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse.Here,we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle la⁃ser pulse.The shift of the central frequency and change of the bandwidth induced by the EOS detection are calcu⁃lated,and then the pulse distortions induced in this detection process are discussed.It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth.These changings decrease when the laser wavelength increases from 2μm to 10μm.This work can help to estimate the performance of the EOS de⁃tection technique in the mid-infrared band and offer a reference for the related experiment as well.展开更多
In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxid...In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxide substrate and a continuous vanadium dioxide(VO_(2))reflector layer.When the Fermi energy level of the Dirac semimetal is 10 meV,the absorber absorbs more than 90%in the 39.06-84.76 THz range.Firstly,taking advantage of the tunability of the conductivity of the Dirac semimetal,dynamic tuning of the absorption frequency can be achieved by changing the Fermi energy level of the Dirac semimetal without the need to optimise the geometry and remanufacture the structure.Secondly,the structure has been improved by the addition of the phase change material VO_(2),resulting in a much higher absorption performance of the absorber.Since VO_(2)is a temperature-sensitive metal oxide with an insulating phase below the phase transition temperature(about 68℃)and a metallic phase above the phase transition temperature,this paper also analyses the effect of VO_(2)on the absorptive performance at different temperatures,with the aim of further improving absorber performance.展开更多
Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting the...Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.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
This paper analyzed 11 lubricating oil 50-1-4Ф samples of different base oil content （standard oil） and 28 used oil samples by Fourier transform mid-infrared spectrometer （FTIR）. First, the absorption peak of 1 4...This paper analyzed 11 lubricating oil 50-1-4Ф samples of different base oil content （standard oil） and 28 used oil samples by Fourier transform mid-infrared spectrometer （FTIR）. First, the absorption peak of 1 465 cm 1 was selected as the characteristic peak for determining their kinematic viscosities. And then correlation of the kinematic viscosity and the absorbance at characteristic peaks of corresponding infrared spectrum of standard oil and used oil samples was analyzed, re- spectively, and two regression equations were proposed. Finally, the regression equation of standard oil was corrected through other 20 new oil samples. The results show that determining kinematic viscosity of new lubricating oil 50-1-4Ф and the used one by FTIR is feasible and reliable.展开更多
A series of aviation lubrication oil 50-1-4φ samples were prepared with different RP-3 content, and then these sam- ples were analyzed by Fourier transform mid-infrared spectrometer （FTIR）. The infrared region of ...A series of aviation lubrication oil 50-1-4φ samples were prepared with different RP-3 content, and then these sam- ples were analyzed by Fourier transform mid-infrared spectrometer （FTIR）. The infrared region of 805--755 cm-1 was selected as quantitative area for determining fuel pollution level of aviation lubrication oil. Finally, correlation of the testing peak area and the fuel pollution level of corresponding samples were analyzed, and the regression equation was proposed. The results show that determining jet fuel pollution level of aviation lubricating oil by FTIR is feasible and reliable.展开更多
A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central fre...A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.展开更多
This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. C...This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.展开更多
A multidisciplinary approach for the production and characterization of a series of high concentration Er3+activated SrLaGa3 O7(abbreviated as Er:SLGO)crystal fibers is shown to have a great promise for implementation...A multidisciplinary approach for the production and characterization of a series of high concentration Er3+activated SrLaGa3 O7(abbreviated as Er:SLGO)crystal fibers is shown to have a great promise for implementation in mid-infrared laser applications.The current approach includes the design and formation of unique layered tetrahedral network structures with several kinds of rare earth(RE)ions including Er ions distributing statistically between layers,such as Er:SLGO,Er,Nd:SLGO,Er,Yb,Ho:SLGO,Er,Eu:SLGO and Er,Ho:SLGO.Five kinds of Er:SLGO crystal fibers were designed to grow via a micropulling down method.Spectroscopic analyses show that Er,Yb,Ho:SLGO and Nd,Er:SLGO crystal fibers were superiorly endowed with inhomogeneous broadening absorption and strong emission.The unique structural components design enables the generation of improved absorption and emission recombination,and the inhibition of self-termination as well.Generally,the use of structural components design may warrant high-efficiency emissions in RE-doped crystal fibers.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
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
Because of the excellent light-trapping ability of black silicon,it has emerged as a versatile substrate for photothermic applications.In this paper,multi-nanostructured black silicon with wide-band mid-infrared absor...Because of the excellent light-trapping ability of black silicon,it has emerged as a versatile substrate for photothermic applications.In this paper,multi-nanostructured black silicon with wide-band mid-infrared absorption properties for application in pyroelectric detectors is reported.Black silicon is fabricated on a substrate surface masked by Ag nanoparticle arrays using single-step etching of C_(4)F_(8)and SF_(6)plasma.The low absorption of black silicon in the mid-infrared region is improved when a secondary nanostructure with Pt nanoparticles and SiO_(2)thin films is deposited on the surface of the prepared black silicon by microelectromechanical system(MEMS)processes.Electrons are scattered at particle boundary,resulting in dielectric loss to incident infrared(IR)region.Compared to single black silicon,the structure decorated with the multi-nanostructure can achieve higher infrared absorption,which is contributed to the high-dielectric loss properties of the Pt nanoparticles.Simulations and experiments show that the thickness of black silicon and number of layers of platinum particles contribute to mid-infrared absorption,with wavelength ranging from 2.5 to 20.0μm,and the absorption reaches~90%.The proposed absorber provides a promising solution for thermal detectors.展开更多
Intense 1-5 μm infrared emission from near-to mid-infrared was obtained from Ho3+/Yb3+codoped TeO2-ZnF2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation,and the e...Intense 1-5 μm infrared emission from near-to mid-infrared was obtained from Ho3+/Yb3+codoped TeO2-ZnF2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation,and the emission intensity can be enhanced with the increase of ZnF2 content.Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra.The stimulated emission cross section of 5 I6→5 I8(1.2 μm),5 I7→5 I8(2.0μm),5 I6→5 I7(2.85 μm) and 5 I5→5 I6(4.0 μm) transitions were calculated to reach 0.639 × 10-20,0.760 ×10-20,0.985×10 20 and 0.484 × 10-20 cm2,respectively.The energy transfer coefficients(CDA) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho3+ and Yb3+were figured out.Our results demonstrate that these TeO2-ZnF2 glasses,which possess good thermal stability and transparency,low phonon energy(about 600 cm-1),excellent near-and mid-infrared emission in the range of 1-5 μm wavelength,would be promising material for infrared optical fibers and infrared lasers.展开更多
A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 ...A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared emissions.When the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.展开更多
Based on the rate equations describing the erbium-doped fluoride glass （ZBLAN） fibre lasers with different pumping configurations being taken into account, this paper presents theoretical calculations related to the...Based on the rate equations describing the erbium-doped fluoride glass （ZBLAN） fibre lasers with different pumping configurations being taken into account, this paper presents theoretical calculations related to the dynamic population density and the operation performance of a high power mid-infrared all-fibre erbium-doped ZBLAN fibre laser. It shows that the ground-state absorption, excited-state absorption and energy-transfer-upconversion processes co-exist and produce a population balance, causing the laser to operate stably at a continuous wave state. A good agreement between the theoretical results and recent experimental measurement is obtained. Furthermore, the laser structure parameters including fibre length, reflectance of output fibre Bragg grating and pumping configurations are quantitatively optimised to achieve the best performance. The results show, as expected, that the slope efficiency of the fibre laser can be improved significantly through optimisation, which then provides an important guide for the design of high-performance mid-infrared erbium-doped ZBLAN fibre lasers.展开更多
We demonstrate a high-emciency mid-infrared picosecond optical parametric oscillator （OPO） based on MgO doped periodically poled lithium niobate （MgO：PPLN） with a laser diode array （LDA） pumped Innoslab amplifi...We demonstrate a high-emciency mid-infrared picosecond optical parametric oscillator （OPO） based on MgO doped periodically poled lithium niobate （MgO：PPLN） with a laser diode array （LDA） pumped Innoslab amplifier as the pumping source. Under a 16 W synchronously pumping power, 4.5 W of idler light at 2896nm is obtained. A tuning range of idler light from 2688nm to 3016nm is achieved, within which the highest optical-optical conversion ettlciency from pump power to OPO output is 35.1%. Moreover, a signal light of -500mW from 1644 to 1700nm with a repetition rate of 233.8 MHz is generated.展开更多
A new method to achieve 2-μm pulsed fiber lasers based on a supercontinuum （SC） is demonstrated. The incident pump light is a pulsed SC which contains a pump light and a signal light at the same time. The initial s...A new method to achieve 2-μm pulsed fiber lasers based on a supercontinuum （SC） is demonstrated. The incident pump light is a pulsed SC which contains a pump light and a signal light at the same time. The initial signal of the seed laser is provided by the incident pump light and amplified in the cavity. Based on this, we obtain a 2-μm pulsed laser with pulse repetition rate of 50 kHz and pulse width of 2 ns from the Tm-doped fiber laser. This 2-μm pulsed laser is amplified by two stages of fiber amplifiers, then the amplified laser is used for mid-infrared （mid-IR） SC generation in a 10-m length of ZrF4-BaF2-LaF3-AIF3-NaF （ZBLAN） fiber. An all-fiber-integrated mid-IR SC with spectrum ranging from 1.8 ~tm to 4.3 μm is achieved. The maximal average output power of the mid-IR SC from the ZBLAN fiber is 1.24 W （average output power beyond 2.5 μm is 340 mW）, corresponding to an output efficiency of 6.6% with respect to the 790-nm pump power.展开更多
Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Se...Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Setaria italica have been chosen as suitable monocotyledonous models for plants possessing the C4 pathway of photosynthesis including sorghum,maize,sugarcane,switchgrass and Miscanthus×giganteus.Accurate partial least squares regression（PLSR）models to predict S.italica stem composition have been generated,based upon Fourier transform mid-infrared（FTIR）spectra and calibrated with wet chemistry determinations of ground S.italica stem material measured using a modified version of the US National Renewable Energy Laboratory（NREL）acid hydrolysis protocol.The models facilitated a high-throughput screening analysis for glucan,xylan,Klason lignin and acid soluble lignin（ASL）in a collection of 183 natural S.italica variants and clustered them into classes,some possessing unique chemotypes.The predictive models provide a highly efficient screening tool for large scale breeding programs aimed at identifying lines or mutants possessing unique cell wall chemotypes.Genes encoding key catalytic enzymes of the lignin biosynthesis pathway exhibit a high level of conservation with matching expression profiles,measured by RT-q PCR,among accessions of S.italica,which closely mirror profiles observed in the different developmental regions of an elongating internode of S.viridis by RNASeq.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61775050).
文摘Mid-infrared(MIR)-polarized thermal emission has broad applications in areas such as molecular sensing,information encryption,target detection,and optical communication.However,it is difficult for objects in nature to produce polarized thermal emission.Moreover,simultaneously generating and modulating broadband MIR thermal emission with both circular and linear polarization is even more difficult.We present a chiral plasmonic metasurface emitter(CPME)composed of asymmetric L-shaped and I-shaped antennas.The CPME consists of In_(3)SbTe_(2)(IST)phase-change material(PCM)antennas,an Al_(2)O_(3) dielectric layer,and an Au substrate.It is demonstrated that the CPME can selectively emit polarized light with different polarization states.Numerical simulations show that the CPME can achieve full Stokes parameter control of MIR thermal emission.By changing the state of the PCM IST,the spectral emissivity of 0 deg,45 deg,90 deg,and 135 deg linearly polarized(LP)lights and left-handed/right-handed circularly polarized(LCP/RCP)lights can be adjusted.In the crystalline state,the CPME exhibits the total degree of polarization(DoP)greater than 0.5 in the wavelength range of 3.4 to 5.3μm,the degree of linear polarization(DoLP)greater than 0.4 in the range of 3.0 to 5.1μm,and the degree of circular polarization(DoCP)greater than 0.4 in the range of 4.5 to 5.6μm.The physical mechanism of polarized emission has been investigated fully based on the near-field intensity distribution and power loss distribution.Finally,the potential applications of the designed CPME in infrared polarization detection and antidetection are verified through numerical calculations.
基金Supported by the National Natural Science Foundation of China(12064028)Jiangxi Provincial Natural Science Foundation(20232BAB201045).
文摘Electro-Optic Sampling(EOS)detection technique has been widely used in terahertz science and tech⁃nology,and it also can measure the field time waveform of the few-cycle laser pulse.Its frequency response and band limitation are determined directly by the electro-optic crystal and duration of the probe laser pulse.Here,we investigate the performance of the EOS with thin GaSe crystal in the measurement of the mid-infrared few-cycle la⁃ser pulse.The shift of the central frequency and change of the bandwidth induced by the EOS detection are calcu⁃lated,and then the pulse distortions induced in this detection process are discussed.It is found that this technique produces a red-shift of the central frequency and narrowing of the bandwidth.These changings decrease when the laser wavelength increases from 2μm to 10μm.This work can help to estimate the performance of the EOS de⁃tection technique in the mid-infrared band and offer a reference for the related experiment as well.
文摘In this paper,a tunable metamaterial absorber based on a Dirac semimetal is proposed.It consists of three different structures,from top to bottom,namely a double semicircular Dirac semimetal resonator,a silicon dioxide substrate and a continuous vanadium dioxide(VO_(2))reflector layer.When the Fermi energy level of the Dirac semimetal is 10 meV,the absorber absorbs more than 90%in the 39.06-84.76 THz range.Firstly,taking advantage of the tunability of the conductivity of the Dirac semimetal,dynamic tuning of the absorption frequency can be achieved by changing the Fermi energy level of the Dirac semimetal without the need to optimise the geometry and remanufacture the structure.Secondly,the structure has been improved by the addition of the phase change material VO_(2),resulting in a much higher absorption performance of the absorber.Since VO_(2)is a temperature-sensitive metal oxide with an insulating phase below the phase transition temperature(about 68℃)and a metallic phase above the phase transition temperature,this paper also analyses the effect of VO_(2)on the absorptive performance at different temperatures,with the aim of further improving absorber performance.
基金supported by the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0301000)the Chongqing Technology Innovation and Application Develop-ment Project(Grant No.CSTB2022TIAD-DEX0031).
文摘Tunable mid-infrared lasers are essential for optical sensing and imaging.Existing technologies,however,face challenges in simultaneously achieving broadband spectral tunability and ultra-rapid scan rates,limiting their utility in dynamic scenarios such as real-time characterization of multiple molecular absorption bands.We present a high-speed approach for broadband wavelength sweeping in the mid-infrared region,leveraging spectral focusing via difference-frequency generation between a chirped fiber laser and an asynchronous,frequency-modulated electro-optic comb.This method enables pulse-to-pulse spectral tuning at a speed of 5.6 THz∕μs with 380 elements.Applied to spectroscopic sensing,our technique achieves broad spectral coverage(2600 to 3780 cm−1)with moderate spectral resolution(8 cm−1)and rapid acquisition time(-6.3μs).Notably,the controllable electro-optic comb facilitates high scan rates of up to 2 Mscans∕s across the full spectral range(corresponding to a speed of 60 THz∕μs),with trade-offs in number of elements(-30)and spectral point spacing or resolution(33 cm−1).Nevertheless,these capabilities make our platform highly promising for applications such as flow cytometry,chemical reaction monitoring,and mid-infrared ranging and imaging.
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.
文摘This paper analyzed 11 lubricating oil 50-1-4Ф samples of different base oil content （standard oil） and 28 used oil samples by Fourier transform mid-infrared spectrometer （FTIR）. First, the absorption peak of 1 465 cm 1 was selected as the characteristic peak for determining their kinematic viscosities. And then correlation of the kinematic viscosity and the absorbance at characteristic peaks of corresponding infrared spectrum of standard oil and used oil samples was analyzed, re- spectively, and two regression equations were proposed. Finally, the regression equation of standard oil was corrected through other 20 new oil samples. The results show that determining kinematic viscosity of new lubricating oil 50-1-4Ф and the used one by FTIR is feasible and reliable.
文摘A series of aviation lubrication oil 50-1-4φ samples were prepared with different RP-3 content, and then these sam- ples were analyzed by Fourier transform mid-infrared spectrometer （FTIR）. The infrared region of 805--755 cm-1 was selected as quantitative area for determining fuel pollution level of aviation lubrication oil. Finally, correlation of the testing peak area and the fuel pollution level of corresponding samples were analyzed, and the regression equation was proposed. The results show that determining jet fuel pollution level of aviation lubricating oil by FTIR is feasible and reliable.
基金Project supported by the National Key Scientific Instrument and Equipment Development,China(Grant No.2014YQ060537)the National Key Research and Development Program,China(Grant No.2016YFC0201103)
文摘A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos 10474071, 60637010, 60671036 and60278001)Tianjin Applied Fundamental Research Project, China (07JCZDJC05900)
文摘This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.
基金Project supported by National Natural Science Foundation of China(51832007,51472240,51872286,61675204)Science and Technology Plan Leading Project of Fujian Province(2018H0046)+1 种基金State Key Laboratory of Rare Earth Resource Utilization(RERU2018004,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences)the National Key Research and Development Program of China(2016YFB0701002)。
文摘A multidisciplinary approach for the production and characterization of a series of high concentration Er3+activated SrLaGa3 O7(abbreviated as Er:SLGO)crystal fibers is shown to have a great promise for implementation in mid-infrared laser applications.The current approach includes the design and formation of unique layered tetrahedral network structures with several kinds of rare earth(RE)ions including Er ions distributing statistically between layers,such as Er:SLGO,Er,Nd:SLGO,Er,Yb,Ho:SLGO,Er,Eu:SLGO and Er,Ho:SLGO.Five kinds of Er:SLGO crystal fibers were designed to grow via a micropulling down method.Spectroscopic analyses show that Er,Yb,Ho:SLGO and Nd,Er:SLGO crystal fibers were superiorly endowed with inhomogeneous broadening absorption and strong emission.The unique structural components design enables the generation of improved absorption and emission recombination,and the inhibition of self-termination as well.Generally,the use of structural components design may warrant high-efficiency emissions in RE-doped crystal fibers.
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 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financially supported by the National Natural Science Foundation of China(No.61874137)Shandong Provincial Key Research and Development Program(No.2020CXGC010203)the National Key Research and Development Project(No.2019YFB2005705)。
文摘Because of the excellent light-trapping ability of black silicon,it has emerged as a versatile substrate for photothermic applications.In this paper,multi-nanostructured black silicon with wide-band mid-infrared absorption properties for application in pyroelectric detectors is reported.Black silicon is fabricated on a substrate surface masked by Ag nanoparticle arrays using single-step etching of C_(4)F_(8)and SF_(6)plasma.The low absorption of black silicon in the mid-infrared region is improved when a secondary nanostructure with Pt nanoparticles and SiO_(2)thin films is deposited on the surface of the prepared black silicon by microelectromechanical system(MEMS)processes.Electrons are scattered at particle boundary,resulting in dielectric loss to incident infrared(IR)region.Compared to single black silicon,the structure decorated with the multi-nanostructure can achieve higher infrared absorption,which is contributed to the high-dielectric loss properties of the Pt nanoparticles.Simulations and experiments show that the thickness of black silicon and number of layers of platinum particles contribute to mid-infrared absorption,with wavelength ranging from 2.5 to 20.0μm,and the absorption reaches~90%.The proposed absorber provides a promising solution for thermal detectors.
基金Project supported by the National Natural Science Foundation of China (11574260)Hunan Provincial Graduate Research Innovation Project (CX2017B283)。
文摘Intense 1-5 μm infrared emission from near-to mid-infrared was obtained from Ho3+/Yb3+codoped TeO2-ZnF2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation,and the emission intensity can be enhanced with the increase of ZnF2 content.Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra.The stimulated emission cross section of 5 I6→5 I8(1.2 μm),5 I7→5 I8(2.0μm),5 I6→5 I7(2.85 μm) and 5 I5→5 I6(4.0 μm) transitions were calculated to reach 0.639 × 10-20,0.760 ×10-20,0.985×10 20 and 0.484 × 10-20 cm2,respectively.The energy transfer coefficients(CDA) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho3+ and Yb3+were figured out.Our results demonstrate that these TeO2-ZnF2 glasses,which possess good thermal stability and transparency,low phonon energy(about 600 cm-1),excellent near-and mid-infrared emission in the range of 1-5 μm wavelength,would be promising material for infrared optical fibers and infrared lasers.
基金Project supported by the National Natural Science Foundation of China(51972149,51872307,61935010,51702124)Key-Area Research and Development Program of Guangdong Province(2020B090922006)。
文摘A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared emissions.When the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.
基金supported by the China Postdoctoral Science Foundation (Grant No. 20090451417)the China Postdoctoral Science Special Foundation (Grant No. 201003693)+1 种基金the Fundamental Research Funds for the Central Universities of China (Grant No. ZYGX2009J053)the National Natural Science Foundation of China (Grant No. 60736038)
文摘Based on the rate equations describing the erbium-doped fluoride glass （ZBLAN） fibre lasers with different pumping configurations being taken into account, this paper presents theoretical calculations related to the dynamic population density and the operation performance of a high power mid-infrared all-fibre erbium-doped ZBLAN fibre laser. It shows that the ground-state absorption, excited-state absorption and energy-transfer-upconversion processes co-exist and produce a population balance, causing the laser to operate stably at a continuous wave state. A good agreement between the theoretical results and recent experimental measurement is obtained. Furthermore, the laser structure parameters including fibre length, reflectance of output fibre Bragg grating and pumping configurations are quantitatively optimised to achieve the best performance. The results show, as expected, that the slope efficiency of the fibre laser can be improved significantly through optimisation, which then provides an important guide for the design of high-performance mid-infrared erbium-doped ZBLAN fibre lasers.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61275142,61308042,and 51321091the National Key Scientific Instrument and Equipment Development Project under Grant No 2011YQ030127the China Postdoctoral Science Foundation under Grant No 2014T70633
文摘We demonstrate a high-emciency mid-infrared picosecond optical parametric oscillator （OPO） based on MgO doped periodically poled lithium niobate （MgO：PPLN） with a laser diode array （LDA） pumped Innoslab amplifier as the pumping source. Under a 16 W synchronously pumping power, 4.5 W of idler light at 2896nm is obtained. A tuning range of idler light from 2688nm to 3016nm is achieved, within which the highest optical-optical conversion ettlciency from pump power to OPO output is 35.1%. Moreover, a signal light of -500mW from 1644 to 1700nm with a repetition rate of 233.8 MHz is generated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61235008 and 61077076)
文摘A new method to achieve 2-μm pulsed fiber lasers based on a supercontinuum （SC） is demonstrated. The incident pump light is a pulsed SC which contains a pump light and a signal light at the same time. The initial signal of the seed laser is provided by the incident pump light and amplified in the cavity. Based on this, we obtain a 2-μm pulsed laser with pulse repetition rate of 50 kHz and pulse width of 2 ns from the Tm-doped fiber laser. This 2-μm pulsed laser is amplified by two stages of fiber amplifiers, then the amplified laser is used for mid-infrared （mid-IR） SC generation in a 10-m length of ZrF4-BaF2-LaF3-AIF3-NaF （ZBLAN） fiber. An all-fiber-integrated mid-IR SC with spectrum ranging from 1.8 ~tm to 4.3 μm is achieved. The maximal average output power of the mid-IR SC from the ZBLAN fiber is 1.24 W （average output power beyond 2.5 μm is 340 mW）, corresponding to an output efficiency of 6.6% with respect to the 790-nm pump power.
文摘Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Setaria italica have been chosen as suitable monocotyledonous models for plants possessing the C4 pathway of photosynthesis including sorghum,maize,sugarcane,switchgrass and Miscanthus×giganteus.Accurate partial least squares regression（PLSR）models to predict S.italica stem composition have been generated,based upon Fourier transform mid-infrared（FTIR）spectra and calibrated with wet chemistry determinations of ground S.italica stem material measured using a modified version of the US National Renewable Energy Laboratory（NREL）acid hydrolysis protocol.The models facilitated a high-throughput screening analysis for glucan,xylan,Klason lignin and acid soluble lignin（ASL）in a collection of 183 natural S.italica variants and clustered them into classes,some possessing unique chemotypes.The predictive models provide a highly efficient screening tool for large scale breeding programs aimed at identifying lines or mutants possessing unique cell wall chemotypes.Genes encoding key catalytic enzymes of the lignin biosynthesis pathway exhibit a high level of conservation with matching expression profiles,measured by RT-q PCR,among accessions of S.italica,which closely mirror profiles observed in the different developmental regions of an elongating internode of S.viridis by RNASeq.
