Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show ...Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show that collective SRS in the plasma produced by ablating a polyimide film is detected for the ID beams,but is suppressed by adding a toe before the main pulse of the ID beams.The toe also strongly influences SRS of both the ID and DD beams excited in the plasma generated in the hohlraum.When a toe is used,the SRS spectra of the DD beams show that SRS tends to be excited in lower plasma density,which will result in a lower risk of super-hot electrons.Measurements of hot electrons support this conclusion.This research will help us produce a better pulse design for this new ignition path.展开更多
Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of supr...Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.展开更多
We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon–photon interaction via the backward stimulated Brillouin scattering(BSBS)proc...We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon–photon interaction via the backward stimulated Brillouin scattering(BSBS)process.The coherent photon–phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator.The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly.When the Duffing nonlinearity is weak,the squeezing degree of the mechanical mode in the presence of BSBS can be improved by more than one order of magnitude compared with that in the absence of BSBS.Our scheme may be extended to other quantum systems to study novel quantum effects.展开更多
We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equatio...We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.展开更多
A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in thi...A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in this paper.High-order acoustic modes(HOAMs)are used to achieve individual or simultaneous measurement of the two parameters.Transverse acoustic waves(TAWs)involved in the FSBS process can efficiently sense the mechanical or environmental changes outside the fiber cladding,which will be reflected in a linear shift of the acoustic resonance frequency.By analyzing the frequencies of specific scattering peaks,the temperature and acoustic impedance outside the fiber cladding can be obtained simultaneously.The highest measured temperature and acoustic impedance sensitivities are 184.93 k Hz/℃and444.56 k Hz/MRayl,and the measurement accuracies are 0.09℃and 0.009 MRayl,respectively,which are both at desirable levels.We believe this work can provide potential application solutions for sensing fields involving temperature or acoustic impedance measurements.展开更多
Persistent luminescence is a unique optical phenomenon that continues to emit light for minutes or even hours after the excitation stops,which can significantly enhance the sensitivity and signal-to-noise ratio of ima...Persistent luminescence is a unique optical phenomenon that continues to emit light for minutes or even hours after the excitation stops,which can significantly enhance the sensitivity and signal-to-noise ratio of imaging[1].Among numerous persistent luminescence materials,lanthanide-doped fluoride nanoparticles have shown tunable persistent luminescence across the UV-vis-NIR spectrum(200-1700 nm)under X-ray excitation and adjustable size,promising significant applications in deep-tissue imaging[2,3],security encryption,and data storage[4].In particular,those exhibiting NIR-II luminescence(1000-1700 nm)provide key advantages such as deeper tissue penetration,higher contrast,and minimal interference from biological autofluorescence.However,challenges such as low brightness and rapid signal decay,especially in the NIR-II region,limit their effectiveness in long-term monitoring,including tumor theranostics[5].Traditional approaches like size control and surface passivation yield only marginal improvements,underscoring the need for next-generation nanoparticles with superior NIR-II brightness.展开更多
Large-angle stimulated Raman scattering(LA-SRS)in a longitudinally inhomogeneous plasma with a transverse density modulation is studied using a three-wave coupled model and numerical simulations.The simulations show t...Large-angle stimulated Raman scattering(LA-SRS)in a longitudinally inhomogeneous plasma with a transverse density modulation is studied using a three-wave coupled model and numerical simulations.The simulations show that the scattering angle of SRS in a longitudinally inhomogeneous plasma can be significantly affected by transverse density modulation.Under transverse density modulation conditions,the laser focuses into underdense regions,owing to the transversely modulated refractive index.The angle of LA-SRS,neither a purely 90° angle side scattering nor purely backscattering,is almost consistent with the specific angle at which the density inhomogeneity vanishes.In modulated plasmas,the nonuniform distribution of laser intensity shifts the regions of scattering and gain compared with those in uniform plasmas,ultimately affecting the laser transmission.SRS is suppressed in weakly modulated regimes,whereas it is enhanced under strong modulation conditions,and a theoretical criterion distinguishing between strong and weak modulation is established.展开更多
The major aim of stroke therapy is to stimulate brain repair and improve behavioral recovery after cerebral ischemia.One option is to stimulate endogenous neurogenesis in the subventricular zone and direct the newly f...The major aim of stroke therapy is to stimulate brain repair and improve behavioral recovery after cerebral ischemia.One option is to stimulate endogenous neurogenesis in the subventricular zone and direct the newly formed neurons to the damaged area.However,only a small percentage of these neurons survive,and many do not reach the damaged area,possibly because the corpus callosum impedes the migration of subventricular zone-derived stem cells into the lesioned cortex.A second major obstacle to stem cell therapy is the strong inflammatory reaction induced by cerebral ischemia,whereby the associated phagocytic activity of brain macrophages removes both therapeutic cells and/or cell-based drug carriers.To address these issues,neurogenesis was electrically stimulated in the subventricular zone,followed by isolation of proliferating cells,including newly formed neurons,which were subsequently mixed with a nutritional hydrogel.This mixture was then transferred to the stroke cavity of day 14 post-stroke mice.We found that the performance of the treated animals improved in behavioral tests,including novel object,open field,hole board,grooming,and“time-to-feel”adhesive tape tests.Furthermore,immunostaining revealed that the stem cell marker nestin,the neuroepithelial marker Mash1,and the immature neuronal marker doublecortin-positive cells survived in the transplanted area for 2 weeks,possibly due to reduced phagocytic activity and supportive angiogenesis.These results clearly indicate that the transplantation of committed subventricular zone stem cells combined with a protective nutritional gel directly into the infarct cavity after the peak of stroke-induced neuroinflammation represents a feasible approach to improve neurorestoration after cerebral ischemia.展开更多
A novel scheme to suppress both stimulated Brillouin scattering(SBS) and stimulated Raman scattering(SRS) by combining an alternating frequency(AF) laser and a transverse magnetic field is proposed. The AF laser allow...A novel scheme to suppress both stimulated Brillouin scattering(SBS) and stimulated Raman scattering(SRS) by combining an alternating frequency(AF) laser and a transverse magnetic field is proposed. The AF laser allows the laser frequency to change discretely and alternately over time. The suppression of SBS is significant as long as the AF difference is greater than the linear growth rate of SBS or the alternating time of the laser frequency is shorter than the linear growth time of SBS. However, the AF laser proves ineffective in suppressing SRS, which usually has a much higher linear growth rate than SBS. To remedy that, a transverse magnetic field is included to suppress the SRS instability. The electrons trapped in the electron plasma waves(EPWs) of SRS can be accelerated by the surfatron mechanism in a transverse magnetic field and eventually detrapped. While continuously extracting energy from EPWs, the EPWs are dissipated and the kinetic inflation of SRS is suppressed. The one-dimensional particle-in-cell simulation results show that both SBS and SRS can be effectively suppressed by combining the AF laser with a transverse magnetic field with tens of Tesla. The total reflectivity can be dramatically reduced by more than one order of magnitude. These results provide a potential reference for controlling SBS and SRS under the related parameters of inertial confinement fusion.展开更多
Effective monitoring of the structural health of combined coal-rock under complex geological conditions by pressure stimulated currents(PSCs)has great potential for the understanding of dynamic disasters in undergroun...Effective monitoring of the structural health of combined coal-rock under complex geological conditions by pressure stimulated currents(PSCs)has great potential for the understanding of dynamic disasters in underground engineering.To reveal the effect of this way,the uniaxial compression experiments with PSC monitoring were conducted on three types of coal-rock combination samples with different strength combinations.The mechanism explanation of PSCs are investigated by resistivity test,atomic force microscopy(AFM)and computed tomography(CT)methods,and a PSC flow model based on progressive failure process is proposed.The influence of strength combinations on PSCs in the progressive failure process are emphasized.The results show the PSC responses between rock part,coal part and the two components are different,which are affected by multi-scale fracture characteristics and electrical properties.As the rock strength decreases,the progressive failure process changes obviously with the influence range of interface constraint effect decreasing,resulting in the different responses of PSC strength and direction in different parts to fracture behaviors.The PSC flow model is initially validated by the relationship between the accumulated charges of different parts.The results are expected to provide a new reference and method for mining design and roadway quality assessment.展开更多
We demonstrate stimulated supercontinuum-radiation of carbon disulfide （CS2） influenced by biological molecules all-trans-stimulated Raman scattering, stimulated Brillouin scattering, all-trans-β-carotene, liquid c...We demonstrate stimulated supercontinuum-radiation of carbon disulfide （CS2） influenced by biological molecules all-trans-stimulated Raman scattering, stimulated Brillouin scattering, all-trans-β-carotene, liquid core optical fibre-carotene in liquid core optical fibre （LCOF）. By virtue of the broad fluorescence characteristics and large third-order optical nonlinearities of all-trans-β-carotene, the high-order Stokes lines of stimulated Raman scattering （SRS） and the multi-order Stokes lines of stimulated Brillouin scattering （SBS） excitated by SRS are observed at low input-laser energies. The results indicate that the fluorescence not only enhances the SRS, but also the SBS. These Stokes lines generate the SRS-SBS supercontinuum radiation （RBSR）. A flat-amplitude bandwidth of 110 nm from 515 nm to 625 nm is observed when a frequency-doubled Nd：YAG laser at 532 nm with an energy of 0.86 mJ is used. This result is expected to be useful for the multi-wavelength fibre laser.展开更多
We report the preparation of D2 molecules in v=2 level in molecular beam condition. A single longitudinal mode laser system was used for excitation of D2 from （v=0, j=0） to （v=2, j=0） with the scheme of stimulated...We report the preparation of D2 molecules in v=2 level in molecular beam condition. A single longitudinal mode laser system was used for excitation of D2 from （v=0, j=0） to （v=2, j=0） with the scheme of stimulated Raman pumping. An excitation efficiency of 25.2% has been achieved, which was determined by the scheme of resonance-enhanced multiphoton ion- ization. Dependence of relative excitation efficiency on laser energy has been measured. We found that the increasing rate of excitation efficiency became slower as pulse energy of Stokes laser increase, while the excitation efficiency still increases approximately linearly with pump pulse energies up to 60 mJ. The spectral line shapes of Raman transition was also measured at different laser energies and considerable dynamical Stark effect was observed. A single peak was found on the three dimension surface of relative excitation efficiency, indicating the process occurred in the present study is a process of stimulated Raman pumping instead of stimulated adiabatic Raman passage.展开更多
The safety and effectiveness of a novel Chinese one-shot dilation technique based on stimulated diuresis for percutaneous nephrolithotomy（PCNL） were investigated.After the feasibility of the Chinese one-shot dilatio...The safety and effectiveness of a novel Chinese one-shot dilation technique based on stimulated diuresis for percutaneous nephrolithotomy（PCNL） were investigated.After the feasibility of the Chinese one-shot dilation based on stimulated diuresis was verified by an animal study,this technique was applied in the clinical practice.A total of 67 patients in our department underwent the modified PCNL from July 2014 to June 2015.After the renal infundibulum was distended by stimulated diuresis,the kidney was punctured under the ultrasonographic guidance via the fornix of the target calyx.The working channel was dilated using a special designed pencil-shaped fascial dilator.The successful access rate,nephrostomy tract creation time,pre-and postoperative hemoglobin values and serum creatinine concentrations,stone-free rate and complications were recorded and analyzed.The renal infundibulum was successfully distended in all of the patients by the diuresis treatment.Under the ultrasonographic guidance,the successful access rate was 100% and the mean tract creation time was 2.0 min（range：1.5–5.0 min）.The stone-free rate right after surgery was 91.0%.Although the postoperative hemoglobin was significantly reduced（P〈0.01）,transfusion was not clinically necessary.There was no significant difference in serum creatinine concentrations before and after operation（P〉0.05）.No severe complication occurred during or after the PCNL.It was suggested that this Chinese one-shot dilation technique based on stimulated diuresis is an efficient and safe innovation for PCNL,and is even helpful for those patients with non-dilated pelvicaliceal systems.展开更多
Studies on texture and microstructure evolution in hot extruded Al 6061 aluminium alloy reinforced with uncoated and nickel coated SiC p were carried out by electron backscattered diffraction technique.Textures of bot...Studies on texture and microstructure evolution in hot extruded Al 6061 aluminium alloy reinforced with uncoated and nickel coated SiC p were carried out by electron backscattered diffraction technique.Textures of both the alloy and its composite with nickel coated SiC p do exhibit strong β fiber with its axis parallel to the direction of extrusion.In addition to the dominant cube texture（001） 100,fully recrystallized grains with partially equiaxed structure have been observed in the alloy reinforced with uncoated SiC p.The recrystallization texture of this composite can be attributed to the particle stimulated nucleation（PSN） due to the presence of SiC p with size less than 5 μm.Under these conditions,the low value of Zener-Hollomon,Z（～1012s-1） confirms that PSN is one of the dominant mechanisms for recrystallization and is governed by formation of deformation zone rather than stored energy.展开更多
The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive character...The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.展开更多
Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. The localized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scatteri...Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. The localized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber. The phase noise structure is analyzed for an interferometric fiber sensing system, and an unbalanced Michelson interferometer with an optical path difference of 1 m, as well as the phase-generated carrier technique, is used to measure the phase noise. It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold, increases dramatically at first and then gradually becomes flat when the input power is above the threshold, which is similar to the variation in relative intensity noise. It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering, which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering.展开更多
Dy^3+-doped glass-ceramics containing NaCaPO4 crystals were successfully fabricated by heat treatment at base glass,and the luminescence properties were investigated for potential applications in radiation measurement...Dy^3+-doped glass-ceramics containing NaCaPO4 crystals were successfully fabricated by heat treatment at base glass,and the luminescence properties were investigated for potential applications in radiation measurements.The photo luminescence(PL)excitation and emission spectra exhibit transitions related to Dy^3+ions corresponding to the strongest excitation and emission wavelengths at 351 and 575 nm,respectively.The CW-OSL properties as a function of dopant concentration,pre-heating temperature,pre-heating time and signal fading were investigated.The most appropriate Dy^3+ion concentration was found to be 0.25 mol%.The TL glow curves have a broad peak feature peaking at 195±5℃.The fading of the OSL signal would keep stable in five days with the intensity value of about 76.11%.The samples also exhibit good signal reusability and a broad linear dose response range(0.02-1000 Gy).展开更多
With the increasing use of nuclear energy, there is a need for a wider range of efficient dosimeters for radiation detection and assessment. There has been a tremendous growth in the development of radiation detectors...With the increasing use of nuclear energy, there is a need for a wider range of efficient dosimeters for radiation detection and assessment. There has been a tremendous growth in the development of radiation detectors and devices in the past few decades. In recent years, the development of new materials for radiation dosimetry has progressed significantly. Alkaline earth sulfides （AES） have been known for a long time as excellent and versatile phosphor materials. In the present investigation, a number of phosphor samples such as mono-, binary and ternary sulfides of alkaline earths （II^a-VI^b） have been prepared and their TL properties have been studied with respect to exposure （x-ray） response and fading. In this paper, some results on SrS：Eu, Sm and CaS：Eu, Sm phosphors are presented. A type of novel OSL dosimeter is described. The dosimeter takes advantage of the characteristics of charge trapping materials SrS：Eu, Sm and CaS：Eu, Sm that exhibit optically stimulated luminescence （OSL）. The measuring range of the dosimeter is from 0.01 to 1000 Gy. The OSL dosimeters provide capability for remote monitoring radiation locations which are difficult to access and hazardous. This equipment is relatively simple, small in size and has low power consumption. The device is suitable for space radiation dose exploration. In addition, it also can be used in IC and other radiation occasions and has good prospects.展开更多
Stimulated Raman scattering(SRS)microscopy has the ability of noninvasive imaging of specific chemical bonds and been increasingly used in biomedicine in recent years.Two pulsed Gaussian beams are used in traditional ...Stimulated Raman scattering(SRS)microscopy has the ability of noninvasive imaging of specific chemical bonds and been increasingly used in biomedicine in recent years.Two pulsed Gaussian beams are used in traditional SRS microscopes,providing with high lateral and axial spatial resolution.Because of the tight focus of the Gaussian beam,such an SRS microscopy is difficult to be used for imaging deep targets in scattering tissues.The SRS microscopy based on Bessel beams can solve the imaging problem to a certain extent.Here,we establish a theoretical model to calculate the SRS signal excited by two Bessel beams by integrating the SRS signal generation theory with the fractal propagation method.The fractal model of refractive index turbulence is employed to generate the scattering tissues where the light transport is modeled by the beam propagation method.We model the scattering tissues containing chemicals,calculate the SRS signals stimulated by two Bessel beams,discuss the influence of the fractal model parameters on signal generation,and compare them with those generated by the Gaussian beams.The results show that,even though the modeling parameters have great influence on SRS signal generation,the Bessel beams-based SRS can generate signals in deeper scattering tissues.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12205274,12275251,12105270,12205272,12305262,and 12035002)the National Key Laboratory of Plasma Physics(Grant No.JCKYS2024212803)+2 种基金the Fund of the National Key Laboratory of Plasma Physics(Grant No.6142A04230103)the National Key R&D Program of China(Grant No.2023YFA1608400)the National Security Academic Fund(Grant No.U2430207).
文摘Stimulated Raman scattering(SRS)under a new ignition path that combines the advantages of direct-drive(DD)and indirect-drive(ID)schemes is investigated experimentally at the Shenguang-100 kJ facility.The results show that collective SRS in the plasma produced by ablating a polyimide film is detected for the ID beams,but is suppressed by adding a toe before the main pulse of the ID beams.The toe also strongly influences SRS of both the ID and DD beams excited in the plasma generated in the hohlraum.When a toe is used,the SRS spectra of the DD beams show that SRS tends to be excited in lower plasma density,which will result in a lower risk of super-hot electrons.Measurements of hot electrons support this conclusion.This research will help us produce a better pulse design for this new ignition path.
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure Activity (Application No. 23068)carried out within the framework of EUROfusion Enabling Research Projects AWP21-ENR-01-CEA02 and AWP24-ENR-IFE-02-CEA-02+3 种基金received funding from Euratom Research and Training Programme 2021–2025 under Grant No. 633053supported by the Ministry of Youth and Sports of the Czech Republic [Project No. LM2023068 (PALS RI)]by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA25030200 and XDA25010100)supported by COST (European Cooperation in Science and Technology) through Action CA21128 PROBONO (PROton BOron Nuclear Fusion: from energy production to medical applicatiOns)
文摘Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.
基金Project supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202400624)the Natural Science Foundation of Chongqing CSTC(Grant No.CSTB2022NSCQBHX0020)+3 种基金the China Electronics Technology Group Corporation 44th Research Institute(Grant No.6310001-2)the Project Grant“Noninvasive Sensing Measurement based on Terahertz Technology”from Province and MOE Collaborative Innovation Centre for New Generation Information Networking and Terminalsthe Key Research Program of CQUPT on Interdisciplinary and Emerging Field(A2018-01)the Venture&Innovation Support program for Chongqing Overseas Returnees Year 2022。
文摘We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon–photon interaction via the backward stimulated Brillouin scattering(BSBS)process.The coherent photon–phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator.The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly.When the Duffing nonlinearity is weak,the squeezing degree of the mechanical mode in the presence of BSBS can be improved by more than one order of magnitude compared with that in the absence of BSBS.Our scheme may be extended to other quantum systems to study novel quantum effects.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174115 and 91836103)。
文摘We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.
文摘A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in this paper.High-order acoustic modes(HOAMs)are used to achieve individual or simultaneous measurement of the two parameters.Transverse acoustic waves(TAWs)involved in the FSBS process can efficiently sense the mechanical or environmental changes outside the fiber cladding,which will be reflected in a linear shift of the acoustic resonance frequency.By analyzing the frequencies of specific scattering peaks,the temperature and acoustic impedance outside the fiber cladding can be obtained simultaneously.The highest measured temperature and acoustic impedance sensitivities are 184.93 k Hz/℃and444.56 k Hz/MRayl,and the measurement accuracies are 0.09℃and 0.009 MRayl,respectively,which are both at desirable levels.We believe this work can provide potential application solutions for sensing fields involving temperature or acoustic impedance measurements.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(No.92361202)National Natural Science Foundation of China(No.12204481).
文摘Persistent luminescence is a unique optical phenomenon that continues to emit light for minutes or even hours after the excitation stops,which can significantly enhance the sensitivity and signal-to-noise ratio of imaging[1].Among numerous persistent luminescence materials,lanthanide-doped fluoride nanoparticles have shown tunable persistent luminescence across the UV-vis-NIR spectrum(200-1700 nm)under X-ray excitation and adjustable size,promising significant applications in deep-tissue imaging[2,3],security encryption,and data storage[4].In particular,those exhibiting NIR-II luminescence(1000-1700 nm)provide key advantages such as deeper tissue penetration,higher contrast,and minimal interference from biological autofluorescence.However,challenges such as low brightness and rapid signal decay,especially in the NIR-II region,limit their effectiveness in long-term monitoring,including tumor theranostics[5].Traditional approaches like size control and surface passivation yield only marginal improvements,underscoring the need for next-generation nanoparticles with superior NIR-II brightness.
基金supported by the National Natural Science Foundation of China under Grant Nos.U2430207,12035002,and 12305258by the CAEP Foundation under Grant No.YZJJZQ2023020.
文摘Large-angle stimulated Raman scattering(LA-SRS)in a longitudinally inhomogeneous plasma with a transverse density modulation is studied using a three-wave coupled model and numerical simulations.The simulations show that the scattering angle of SRS in a longitudinally inhomogeneous plasma can be significantly affected by transverse density modulation.Under transverse density modulation conditions,the laser focuses into underdense regions,owing to the transversely modulated refractive index.The angle of LA-SRS,neither a purely 90° angle side scattering nor purely backscattering,is almost consistent with the specific angle at which the density inhomogeneity vanishes.In modulated plasmas,the nonuniform distribution of laser intensity shifts the regions of scattering and gain compared with those in uniform plasmas,ultimately affecting the laser transmission.SRS is suppressed in weakly modulated regimes,whereas it is enhanced under strong modulation conditions,and a theoretical criterion distinguishing between strong and weak modulation is established.
基金supported by European Union Funding Programme,PNRR,No. 760058(to DMH)the UEFISCDI Project,No. PN-III-P4-IDPCE-2020-059(to APW)
文摘The major aim of stroke therapy is to stimulate brain repair and improve behavioral recovery after cerebral ischemia.One option is to stimulate endogenous neurogenesis in the subventricular zone and direct the newly formed neurons to the damaged area.However,only a small percentage of these neurons survive,and many do not reach the damaged area,possibly because the corpus callosum impedes the migration of subventricular zone-derived stem cells into the lesioned cortex.A second major obstacle to stem cell therapy is the strong inflammatory reaction induced by cerebral ischemia,whereby the associated phagocytic activity of brain macrophages removes both therapeutic cells and/or cell-based drug carriers.To address these issues,neurogenesis was electrically stimulated in the subventricular zone,followed by isolation of proliferating cells,including newly formed neurons,which were subsequently mixed with a nutritional hydrogel.This mixture was then transferred to the stroke cavity of day 14 post-stroke mice.We found that the performance of the treated animals improved in behavioral tests,including novel object,open field,hole board,grooming,and“time-to-feel”adhesive tape tests.Furthermore,immunostaining revealed that the stem cell marker nestin,the neuroepithelial marker Mash1,and the immature neuronal marker doublecortin-positive cells survived in the transplanted area for 2 weeks,possibly due to reduced phagocytic activity and supportive angiogenesis.These results clearly indicate that the transplantation of committed subventricular zone stem cells combined with a protective nutritional gel directly into the infarct cavity after the peak of stroke-induced neuroinflammation represents a feasible approach to improve neurorestoration after cerebral ischemia.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11975059 and 12005021)。
文摘A novel scheme to suppress both stimulated Brillouin scattering(SBS) and stimulated Raman scattering(SRS) by combining an alternating frequency(AF) laser and a transverse magnetic field is proposed. The AF laser allows the laser frequency to change discretely and alternately over time. The suppression of SBS is significant as long as the AF difference is greater than the linear growth rate of SBS or the alternating time of the laser frequency is shorter than the linear growth time of SBS. However, the AF laser proves ineffective in suppressing SRS, which usually has a much higher linear growth rate than SBS. To remedy that, a transverse magnetic field is included to suppress the SRS instability. The electrons trapped in the electron plasma waves(EPWs) of SRS can be accelerated by the surfatron mechanism in a transverse magnetic field and eventually detrapped. While continuously extracting energy from EPWs, the EPWs are dissipated and the kinetic inflation of SRS is suppressed. The one-dimensional particle-in-cell simulation results show that both SBS and SRS can be effectively suppressed by combining the AF laser with a transverse magnetic field with tens of Tesla. The total reflectivity can be dramatically reduced by more than one order of magnitude. These results provide a potential reference for controlling SBS and SRS under the related parameters of inertial confinement fusion.
基金supported by National Key R&D Program of China(No.2022YFC3004705)the National Natural Science Foundation of China(Nos.52074280,52227901 and 52204249)National Natural Science Foundation of China Youth Fund(No.52104230).
文摘Effective monitoring of the structural health of combined coal-rock under complex geological conditions by pressure stimulated currents(PSCs)has great potential for the understanding of dynamic disasters in underground engineering.To reveal the effect of this way,the uniaxial compression experiments with PSC monitoring were conducted on three types of coal-rock combination samples with different strength combinations.The mechanism explanation of PSCs are investigated by resistivity test,atomic force microscopy(AFM)and computed tomography(CT)methods,and a PSC flow model based on progressive failure process is proposed.The influence of strength combinations on PSCs in the progressive failure process are emphasized.The results show the PSC responses between rock part,coal part and the two components are different,which are affected by multi-scale fracture characteristics and electrical properties.As the rock strength decreases,the progressive failure process changes obviously with the influence range of interface constraint effect decreasing,resulting in the different responses of PSC strength and direction in different parts to fracture behaviors.The PSC flow model is initially validated by the relationship between the accumulated charges of different parts.The results are expected to provide a new reference and method for mining design and roadway quality assessment.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10774057 and 10974067)
文摘We demonstrate stimulated supercontinuum-radiation of carbon disulfide （CS2） influenced by biological molecules all-trans-stimulated Raman scattering, stimulated Brillouin scattering, all-trans-β-carotene, liquid core optical fibre-carotene in liquid core optical fibre （LCOF）. By virtue of the broad fluorescence characteristics and large third-order optical nonlinearities of all-trans-β-carotene, the high-order Stokes lines of stimulated Raman scattering （SRS） and the multi-order Stokes lines of stimulated Brillouin scattering （SBS） excitated by SRS are observed at low input-laser energies. The results indicate that the fluorescence not only enhances the SRS, but also the SBS. These Stokes lines generate the SRS-SBS supercontinuum radiation （RBSR）. A flat-amplitude bandwidth of 110 nm from 515 nm to 625 nm is observed when a frequency-doubled Nd：YAG laser at 532 nm with an energy of 0.86 mJ is used. This result is expected to be useful for the multi-wavelength fibre laser.
文摘We report the preparation of D2 molecules in v=2 level in molecular beam condition. A single longitudinal mode laser system was used for excitation of D2 from （v=0, j=0） to （v=2, j=0） with the scheme of stimulated Raman pumping. An excitation efficiency of 25.2% has been achieved, which was determined by the scheme of resonance-enhanced multiphoton ion- ization. Dependence of relative excitation efficiency on laser energy has been measured. We found that the increasing rate of excitation efficiency became slower as pulse energy of Stokes laser increase, while the excitation efficiency still increases approximately linearly with pump pulse energies up to 60 mJ. The spectral line shapes of Raman transition was also measured at different laser energies and considerable dynamical Stark effect was observed. A single peak was found on the three dimension surface of relative excitation efficiency, indicating the process occurred in the present study is a process of stimulated Raman pumping instead of stimulated adiabatic Raman passage.
文摘The safety and effectiveness of a novel Chinese one-shot dilation technique based on stimulated diuresis for percutaneous nephrolithotomy（PCNL） were investigated.After the feasibility of the Chinese one-shot dilation based on stimulated diuresis was verified by an animal study,this technique was applied in the clinical practice.A total of 67 patients in our department underwent the modified PCNL from July 2014 to June 2015.After the renal infundibulum was distended by stimulated diuresis,the kidney was punctured under the ultrasonographic guidance via the fornix of the target calyx.The working channel was dilated using a special designed pencil-shaped fascial dilator.The successful access rate,nephrostomy tract creation time,pre-and postoperative hemoglobin values and serum creatinine concentrations,stone-free rate and complications were recorded and analyzed.The renal infundibulum was successfully distended in all of the patients by the diuresis treatment.Under the ultrasonographic guidance,the successful access rate was 100% and the mean tract creation time was 2.0 min（range：1.5–5.0 min）.The stone-free rate right after surgery was 91.0%.Although the postoperative hemoglobin was significantly reduced（P〈0.01）,transfusion was not clinically necessary.There was no significant difference in serum creatinine concentrations before and after operation（P〉0.05）.No severe complication occurred during or after the PCNL.It was suggested that this Chinese one-shot dilation technique based on stimulated diuresis is an efficient and safe innovation for PCNL,and is even helpful for those patients with non-dilated pelvicaliceal systems.
基金granting financial assistance to carry out this work which is a part of research project No.SR/S3/ME/019/2004-SERC
文摘Studies on texture and microstructure evolution in hot extruded Al 6061 aluminium alloy reinforced with uncoated and nickel coated SiC p were carried out by electron backscattered diffraction technique.Textures of both the alloy and its composite with nickel coated SiC p do exhibit strong β fiber with its axis parallel to the direction of extrusion.In addition to the dominant cube texture（001） 100,fully recrystallized grains with partially equiaxed structure have been observed in the alloy reinforced with uncoated SiC p.The recrystallization texture of this composite can be attributed to the particle stimulated nucleation（PSN） due to the presence of SiC p with size less than 5 μm.Under these conditions,the low value of Zener-Hollomon,Z（～1012s-1） confirms that PSN is one of the dominant mechanisms for recrystallization and is governed by formation of deformation zone rather than stored energy.
基金funded by the National Natural Science Foundation of China (Grants Nos. 41301012, 41771020 and U1405231)Natural Science Foundation of Fujian (Grant No. 2018R1034-5)Innovation Research Team Fund of Fujian Normal University (Grant No. IRTL1705)
文摘The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61177073)the Open Fund of Key Laboratory of Optoelectronic Information and Sensing Technologies of Guangdong Higher Education Institutes, Jinan University, China (Grant No. gdol201101)+1 种基金the Fund of Innovation of Graduate School of NUDT, China (Grant No. B110703)Hunan Provincial Innovation Foundation for Postgraduate,China (Grant No. CX2011B033)
文摘Stimulated Brillouin scattering-induced phase noise is harmful to interferometric fiber sensing systems. The localized fluctuating model is used to study the intensity noise caused by the stimulated Brillouin scattering in a single-mode fiber. The phase noise structure is analyzed for an interferometric fiber sensing system, and an unbalanced Michelson interferometer with an optical path difference of 1 m, as well as the phase-generated carrier technique, is used to measure the phase noise. It is found that the phase noise is small when the input power is below the stimulated Brillouin scattering threshold, increases dramatically at first and then gradually becomes flat when the input power is above the threshold, which is similar to the variation in relative intensity noise. It can be inferred that the increase in phase noise is mainly due to the broadening of the laser linewidth caused by stimulated Brillouin scattering, which is verified through linewidth measurements in the absence and presence of the stimulated Brillouin scattering.
基金Project supported by the National Natural Science Foundation of China(11675260)。
文摘Dy^3+-doped glass-ceramics containing NaCaPO4 crystals were successfully fabricated by heat treatment at base glass,and the luminescence properties were investigated for potential applications in radiation measurements.The photo luminescence(PL)excitation and emission spectra exhibit transitions related to Dy^3+ions corresponding to the strongest excitation and emission wavelengths at 351 and 575 nm,respectively.The CW-OSL properties as a function of dopant concentration,pre-heating temperature,pre-heating time and signal fading were investigated.The most appropriate Dy^3+ion concentration was found to be 0.25 mol%.The TL glow curves have a broad peak feature peaking at 195±5℃.The fading of the OSL signal would keep stable in five days with the intensity value of about 76.11%.The samples also exhibit good signal reusability and a broad linear dose response range(0.02-1000 Gy).
基金Project supported by the National Natural Science Foundation of China (Grant No 10475112)the Western Light Foundation of 2005 years
文摘With the increasing use of nuclear energy, there is a need for a wider range of efficient dosimeters for radiation detection and assessment. There has been a tremendous growth in the development of radiation detectors and devices in the past few decades. In recent years, the development of new materials for radiation dosimetry has progressed significantly. Alkaline earth sulfides （AES） have been known for a long time as excellent and versatile phosphor materials. In the present investigation, a number of phosphor samples such as mono-, binary and ternary sulfides of alkaline earths （II^a-VI^b） have been prepared and their TL properties have been studied with respect to exposure （x-ray） response and fading. In this paper, some results on SrS：Eu, Sm and CaS：Eu, Sm phosphors are presented. A type of novel OSL dosimeter is described. The dosimeter takes advantage of the characteristics of charge trapping materials SrS：Eu, Sm and CaS：Eu, Sm that exhibit optically stimulated luminescence （OSL）. The measuring range of the dosimeter is from 0.01 to 1000 Gy. The OSL dosimeters provide capability for remote monitoring radiation locations which are difficult to access and hazardous. This equipment is relatively simple, small in size and has low power consumption. The device is suitable for space radiation dose exploration. In addition, it also can be used in IC and other radiation occasions and has good prospects.
基金This work was supported in part by the National Key R&D Program of China under Grant No.2018YFC0910600the National Natural Science Foundation of China under Grant Nos.81871397,81627807,11727813,91859109+2 种基金the Shaanxi Science Fund for Distinguished Young Scholars under Grant No.2020JC-27the Shaanxi Young Top-notch Talent of"Special Support Program"the Best Funded Projects for the Scientific and Technological Activities for Excellent Overseas Researchers in Shaanxi Province(2017017)..
文摘Stimulated Raman scattering(SRS)microscopy has the ability of noninvasive imaging of specific chemical bonds and been increasingly used in biomedicine in recent years.Two pulsed Gaussian beams are used in traditional SRS microscopes,providing with high lateral and axial spatial resolution.Because of the tight focus of the Gaussian beam,such an SRS microscopy is difficult to be used for imaging deep targets in scattering tissues.The SRS microscopy based on Bessel beams can solve the imaging problem to a certain extent.Here,we establish a theoretical model to calculate the SRS signal excited by two Bessel beams by integrating the SRS signal generation theory with the fractal propagation method.The fractal model of refractive index turbulence is employed to generate the scattering tissues where the light transport is modeled by the beam propagation method.We model the scattering tissues containing chemicals,calculate the SRS signals stimulated by two Bessel beams,discuss the influence of the fractal model parameters on signal generation,and compare them with those generated by the Gaussian beams.The results show that,even though the modeling parameters have great influence on SRS signal generation,the Bessel beams-based SRS can generate signals in deeper scattering tissues.
