This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fuse...This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared （RMS） average surface roughness values are 0.7 nm and 1.0 rim, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive con- taminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.展开更多
Laser-induced damage in fused silica optics greatly restricts the performances of laser facilities. Gray haze damage,which is always initiated on ceria polished optics, is one of the most important damage morphologies...Laser-induced damage in fused silica optics greatly restricts the performances of laser facilities. Gray haze damage,which is always initiated on ceria polished optics, is one of the most important damage morphologies in fused silica optics.In this paper, the laser-induced gray haze damages of four fused silica samples polished with CeO2, Al2O3, ZrO2, and colloidal silica slurries are investigated. Four samples all present gray haze damages with much different damage densities.Then, the polishing-induced contaminant and subsurface damages in four samples are analyzed. The results reveal that the gray haze damages could be initiated on the samples without Ce contaminant and are inclined to show a tight correlation with the shallow subsurface damages.展开更多
Time Division Multiplexing-Passive Optical Networks(TDM-PONs)play a vital role in Fiberto-the-Home(FTTH)deployments.To improve the service quality of home networks,FTTH is expanding to the Fiber-to-the-Room(FTTR)scena...Time Division Multiplexing-Passive Optical Networks(TDM-PONs)play a vital role in Fiberto-the-Home(FTTH)deployments.To improve the service quality of home networks,FTTH is expanding to the Fiber-to-the-Room(FTTR)scenario,where fibers are deployed to connect individual rooms(i.e.,Fiber In-premises Network(FIN)in the ITU-T G.9940 standard).In this scenario,a point-to-multipoint(P2MP)fiber network is deployed as FTTR FIN to offer gigabit access to each room,which forms a two-tier cascaded network together with the FTTH segment.To optimize the capacity utilization of the cascaded network and reduce the overall system cost,a centralized architecture,known as Centralized Fixed Access Network(C-FAN),has been introduced.C-FAN centralizes the medium access control(MAC)modules of both the FTTH and FTTR networks at the FTTH’s Optical Line Terminal(OLT)for unified control and management of the cascaded network.We develop a unified bandwidth scheduling protocol by extending the ITU-T PON standard for both the upstream and downstream directions of C-FAN.We also propose a unified dynamic bandwidth allocation(UDBA)algorithm for efficient bandwidth allocation for multiple traffic flows in the two-tier cascaded network.Simulations are conducted to evaluate the performance of the proposed control protocol and the UDBA algorithm.The results show that,in comparison to the conventional DBA algorithm,the UDBA algorithm can utilize upstream bandwidth more efficiently to reduce packet delay and loss,without adversely impacting downstream transmission performance.展开更多
We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shif...We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shift with variation of the detuning and power of the cooling laser and study the performance of the diffuse laser cooling mechanism by the absorption linewidth radio?ν_E/?ν_R and light shift|?_R-?_E|using nonlinear spectroscopy.Specifically,when?ν_E/?ν_R reaches a value of 1.57,the temperature and number of cold atoms achieve the optimal cooling effect.This characterization of absorption linewidth and light shift will provide a method to estimate whether diffuse light cooling achieves the best cooling effect,contributing to the future development of isotropic laser cooling for application in quantum sensing.展开更多
Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In ...Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In this study,we investigate the dielectric and optical characteristics of CdSe CQWs with monolayer numbers ranging from 2 to 7,synthesized via thermal injection and atomic layer(c-ALD)deposition techniques.Through a combination of spectroscopic ellipsometry(SE)and first-principles calculations,we demonstrate the significant tunability of the bandgap,refractive index,and extinction coefficient,driven by quantum confinement effects.Our results show a decrease in bandgap from 3.1 to 2.0 eV as the layer thickness increases.Furthermore,by employing a detailed analysis of the absorption spectra,accounting for exciton localization and asymmetric broadening,we precisely capture the relationship between monolayer number and exciton binding energy.These findings offer crucial insights for optimizing CdSe CQWs in optoelectronic device design by leveraging their layer-dependent properties.展开更多
It is a pleasure to contribute a commentary on the very interesting review by Dr.Orcioli-Silva and colleagues1 on the simultaneous measurements of cerebral cortex and muscle tissue oxygenation during exercise in healt...It is a pleasure to contribute a commentary on the very interesting review by Dr.Orcioli-Silva and colleagues1 on the simultaneous measurements of cerebral cortex and muscle tissue oxygenation during exercise in healthy adults using near-infrared spectroscopy(NIRS).The first NIRS measurements of the cerebral cortex and muscle were performed on humans in 19772 and 1982,3 respectively.展开更多
A novel low-coherence digital inline holographic microscope for accurate three-dimensional(3D)position estimation and nanoparticle classification is proposed and validated.Two low-coherence digital inline holograms of...A novel low-coherence digital inline holographic microscope for accurate three-dimensional(3D)position estimation and nanoparticle classification is proposed and validated.Two low-coherence digital inline holograms of a sample containing numerous nanoparticles,generated by two illumination light beams forming a small angle with each other from a low-coherence light source,are employed to determine the nanoparticles’actual 3D positions.Each nanoparticle’s sub-holograms,extracted from the holograms of the sample,are used to reconstruct the intensity scattering image at its respective actual position using the Rayleigh–Sommerfeld backpropagation method.The intensity scattering image of each nanoparticle is then used to classify particles with similar sizes and shapes.The advantages of the proposed system include rapid and highly accurate 3D nanoparticle position determination and nanoparticle classification without the need to pre-prepare patterns or have prior knowledge of the nanoparticle characteristics.展开更多
This study presents a detailed photometric and spectroscopic analysis of the W UMa-type binary NR Cam,using data from the Transiting Exoplanet Survey Satellite(TESS)and ground-based observations.The light curves exhib...This study presents a detailed photometric and spectroscopic analysis of the W UMa-type binary NR Cam,using data from the Transiting Exoplanet Survey Satellite(TESS)and ground-based observations.The light curves exhibit significant variable,with a negative correlation between the brightness of the two maxima—a characteristic of W UMa-type binaries typically attributed to magnetic activity.To explain this behavior,we incorporated a starspot model into our Wilson–Devinney analysis.Our results confirm that NR Cam is a W-subtype,moderately contact binary with a low mass ratio of q=5.75(±0.03)and a fill-out factor of f=33.4(±3.1)%.We also analyzed the orbital period variation using all available times of minima.The resulting O−C diagram reveals a long-term decreasing trend in the orbital period at a rate of dP/dt=−5.18(±0.02)×10^(-8) day yr^(-1),superimposed with a periodic oscillation characterized by an amplitude of A_(3)=0.0019(±0.0001)day and an oscillation period of P_(3)=7.776(±0.003)yr.The long-term decrease is likely due to mass transfer between the binary components,with an estimated mass transfer rate of dM_(2)/dt=1.33(±0.01)×10^(-8)M_(⊙)yr^(-1).The periodic oscillations are likely driven by the light-travel time effect caused by a tertiary companion,with a minimum mass of M_(3)=0.0956(1)M_(⊙)and a maximum separation of 3.841(6)au.Additionally,we considered the possibility that the periodic variation could result from changes in the gravitational quadrupole moment due to magnetic activity cycles,as described by the Applegate mechanism.Our findings confirm that NR Cam is an active binary system,where magnetic activity plays a significant role in its orbital evolution.These results contribute to our understanding of the magnetic dynamics and evolutionary processes in contact binary systems.展开更多
The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strat...The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strategies to minimize the device size are needed.In this paper,we have inversely designed an integrated transverse electric pass(TE-pass)polarizer with a footprint of 2.88μm×2.88μm,which is the smallest footprint ever achieved.A direct binary search algorithm is used to inversely design the device for maximizing the transverse electric(TE)transmission while minimizing transverse magnetic(TM)transmission.Finally,the inverse-designed device provides an average insertion loss of 0.99 dB and an average extinction ratio of 33 dB over a wavelength range of 100 nm.展开更多
Cubic phase Tm^(3+)/Yb^(3+):Y_(2)O_(3) and Tm^(3+)/Yb^(3+)/Gd^(3+):Y_(2)O_(3) phosphors were prepared by low temperature combustion technique for upconversion emission in UV-visible range.The 980 nm excitation has gen...Cubic phase Tm^(3+)/Yb^(3+):Y_(2)O_(3) and Tm^(3+)/Yb^(3+)/Gd^(3+):Y_(2)O_(3) phosphors were prepared by low temperature combustion technique for upconversion emission in UV-visible range.The 980 nm excitation has generated UV emission at 314 nm in tridoped phosphor due to the energy transfer from Tm^(3+) to Gd^(3+)ion.Characteristic emission bands from Tm^(3+) are also observed in both the phosphors.Thermally coupled Stark sublevels ^(1)G_(4(a))(476 nm) and ^(1)G_(4(b))(488 nm) of Tm^(3+) ion were utilised for optical thermometry using fluorescent intensity ratio(FIR) method.The result shows that maximum absolute sensitivity in tridoped phosphor is observed to be 1.33 × 10^(-3) K^(-1) at 298 K.Moreover,temperature rise of phosphor at various pump power densities was also measured and it is estimated to achieve 407 K at the pump power density of 38.46 W/cm^(2).展开更多
The laser-induced damage threshold(LIDT) of optical coating is a limited factor for development of a high peak power laser. The automatic damage testing facility was built to determine the LIDT of optics at 1 064 nm a...The laser-induced damage threshold(LIDT) of optical coating is a limited factor for development of a high peak power laser. The automatic damage testing facility was built to determine the LIDT of optics at 1 064 nm and 355 nm.. The cleanning and processing procedure of the substrate and coating technique were improved, and the damage resistance of high-reflective coating at 1 064 nm was increased.展开更多
In this review paper on heavy ion inertial fusion(HIF),the state-of-the-art scientific results are presented and discussed on the HIF physics,including physics of the heavy ion beam(HIB)transport in a fusion reactor,t...In this review paper on heavy ion inertial fusion(HIF),the state-of-the-art scientific results are presented and discussed on the HIF physics,including physics of the heavy ion beam(HIB)transport in a fusion reactor,the HIBs-ion illumination on a direct-drive fuel target,the fuel target physics,the uniformity of the HIF target implosion,the smoothing mechanisms of the target implosion non-uniformity and the robust target implosion.The HIB has remarkable preferable features to release the fusion energy in inertial fusion:in particle accelerators HIBs are generated with a high driver efficiency of~30%-40%,and the HIB ions deposit their energy inside of materials.Therefore,a requirement for the fusion target energy gain is relatively low,that would be~50-70 to operate a HIF fusion reactor with the standard energy output of 1 GWof electricity.The HIF reactor operation frequency would be~10-15 Hz or so.Several-MJ HIBs illuminate a fusion fuel target,and the fuel target is imploded to about a thousand times of the solid density.Then the DT fuel is ignited and burned.The HIB ion deposition range is defined by the HIB ions stopping length,which would be~1 mm or so depending on the material.Therefore,a relatively large density-scale length appears in the fuel target material.One of the critical issues in inertial fusion would be a spherically uniform target compression,which would be degraded by a non-uniform implosion.The implosion non-uniformity would be introduced by the Rayleigh-Taylor(R-T)instability,and the large densitygradient-scale length helps to reduce the R-T growth rate.On the other hand,the large scale length of the HIB ions stopping range suggests that the temperature at the energy deposition layer in a HIF target does not reach a very-high temperature:normally about 300 eV or so is realized in the energy absorption region,and that a direct-drive target would be appropriate in HIF.In addition,the HIB accelerators are operated repetitively and stably.The precise control of the HIB axis manipulation is also realized in the HIF accelerator,and the HIB wobbling motion may give another tool to smooth the HIB illumination non-uniformity.The key issues in HIF physics are also discussed and presented in the paper.展开更多
Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quali...Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quality was successfully grown via the Czochralski pulling technique.The absorption and fluorescence spectra of the Nd:YSP single crystal were recorded at ambient temperature.The maximum absorption cross section for Nd:YSP single crystal is found to be approximately 3.89×10^(-20) cm^(2).The stimulated emission cross section for Nd:YSP crystal at~1060 nm was determined to be 7.64×10^(20) cm^(2) with the full width half maximum value of 22 nm.The fluorescence lifetime of the Nd3+ions in the Nd:YSP crystal is fitted to be 288μs.Diode-pumped continuous-wave laser operation is firstly realized at approximately 1060 nm.The maximum output power value from the Nd:YSP crystal is 714 mW,corresponding to a slope efficiency of-12.8%.The results indicate that the Nd:YSP crystal with a disordered structure may be a promising disordered laser host.展开更多
An efficient dual-wavelength laser-diode-pumped Nd:YAG ceramic laser operating at 1112 and 1116 nm is demonstrated.We obtain a maximum total output power of 3.43 W including a 1.77 W 1112 nm component and a 1.66 W 111...An efficient dual-wavelength laser-diode-pumped Nd:YAG ceramic laser operating at 1112 and 1116 nm is demonstrated.We obtain a maximum total output power of 3.43 W including a 1.77 W 1112 nm component and a 1.66 W 1116 nm component under a pump power of 16.1 W,corresponding to a slope efficiency of 23.7%and a total optical-to-optical efficiency of 21.3%.展开更多
In close-aperture Z-scan experiments, a small aperture is conventionally located in the far-field thereby enabling the detection of slight changes in the laser beam profile due to the Kerr-lensing effect. In this work...In close-aperture Z-scan experiments, a small aperture is conventionally located in the far-field thereby enabling the detection of slight changes in the laser beam profile due to the Kerr-lensing effect. In this work, by numerically solving the Fresnel-Kirchhoff diffraction integrals, the amount of transmitted power through apertures has been evaluated and a parametric study on the role of the various parameters that can influence this transmitted power has been done. In order to perform a comprehensive analysis, we have used a nonlinear phase shift optimized for nonlocal nonlinear media in our calculations. Our results show that apertures will result in the formation of symmetrical fluctuations on the wings of Z-scan transmittance curves. It is further shown that the appearance of these fluctuations can be ascribed to the natural diffraction of the Gaussian beam as it propagates up to the aperture plane. Our calculations reveal that the nonlocal parameter variations can shift the position of fluctuations along the optical axis, whereas their magnitude depends on the largeness of the induced nonlinear phase shift. It is concluded that since the mentioned fluctuations are produced by the natural diffraction of the Gaussian beam itself, one must take care not to mistakenly interpret them as noise and should not expect to eliminate them from experimental Z-scan transmittance curves by using apertures with different sizes.展开更多
As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with ...As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service experience.With the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and back-haul.Optical access networks would play an important role in F5G to support radio access network and fixed access network.Low-latency PON is a key for cost effective-haul traffic aggregation.In terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple architecture.The fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s phase.In access network,the flexibility and low latency are the two key factors affecting service experience.In this article,we review the evolution of PONs and the challenges of current PONs in detail.We analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU communications.Finally,we discuss the developing trends of future optical access networks.展开更多
One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for ...One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wutzite phase （hexagonal structure）. SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods （sulfur precursor： Na2S） was shown blue shift to 485 nm due to the quantum size effect.展开更多
Ultrafine Y（OH）3 nanoparticles were successfully deposited from an additive-free 0.005 mol/L YCl3 low-temperature bath on the steel cathode at the current density of 0.5 mA/cm2 and bath temperature of 10 oC. Heat tr...Ultrafine Y（OH）3 nanoparticles were successfully deposited from an additive-free 0.005 mol/L YCl3 low-temperature bath on the steel cathode at the current density of 0.5 mA/cm2 and bath temperature of 10 oC. Heat treatment of the prepared Y（OH）3 nanoparticles at 600 oC in air led to the formation of Y2O3 nanoparticles. Thermal behavior and phase transformation during the heat treatment of Y（OH）3 were investigated by differential scanning calorimetry （DSC） and thermogramimetric analysis （TGA）. The morphologies, crystal structures and compositions of the prepared materials were examined by means of scanning and transmission electron microscopy （SEM and TEM） as well as X-ray diffraction （XRD） and FT-IR spectroscopy. The results showed that the prepared Y（OH）3 nanoparticles was essentially amorphous and composed of well dispersed ultrafine particles with size of 4 nm. After heat treatment, the obtained oxide product was well crystallized cubic phase of Y2O3 nanoparticles with the grain size of around 5 nm. It was concluded that low-temperature cathodic electrodeposition offered a facile and feasible way for preparation of ultrafine Y（OH）3 and Y2O3 nanoparticles.展开更多
文摘This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared （RMS） average surface roughness values are 0.7 nm and 1.0 rim, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive con- taminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.
文摘Laser-induced damage in fused silica optics greatly restricts the performances of laser facilities. Gray haze damage,which is always initiated on ceria polished optics, is one of the most important damage morphologies in fused silica optics.In this paper, the laser-induced gray haze damages of four fused silica samples polished with CeO2, Al2O3, ZrO2, and colloidal silica slurries are investigated. Four samples all present gray haze damages with much different damage densities.Then, the polishing-induced contaminant and subsurface damages in four samples are analyzed. The results reveal that the gray haze damages could be initiated on the samples without Ce contaminant and are inclined to show a tight correlation with the shallow subsurface damages.
基金supported by National Nature Science Founding of China(62101372)Open Fund of IPOC(BUPT,IPOC2022A07)+1 种基金State Key Laboratory of Advanced Optical Communication Systems and Networks(2023GZKF11)Leading Youth Talents of Innovation and Entrepreneurship of Gusu(ZXL2023162).
文摘Time Division Multiplexing-Passive Optical Networks(TDM-PONs)play a vital role in Fiberto-the-Home(FTTH)deployments.To improve the service quality of home networks,FTTH is expanding to the Fiber-to-the-Room(FTTR)scenario,where fibers are deployed to connect individual rooms(i.e.,Fiber In-premises Network(FIN)in the ITU-T G.9940 standard).In this scenario,a point-to-multipoint(P2MP)fiber network is deployed as FTTR FIN to offer gigabit access to each room,which forms a two-tier cascaded network together with the FTTH segment.To optimize the capacity utilization of the cascaded network and reduce the overall system cost,a centralized architecture,known as Centralized Fixed Access Network(C-FAN),has been introduced.C-FAN centralizes the medium access control(MAC)modules of both the FTTH and FTTR networks at the FTTH’s Optical Line Terminal(OLT)for unified control and management of the cascaded network.We develop a unified bandwidth scheduling protocol by extending the ITU-T PON standard for both the upstream and downstream directions of C-FAN.We also propose a unified dynamic bandwidth allocation(UDBA)algorithm for efficient bandwidth allocation for multiple traffic flows in the two-tier cascaded network.Simulations are conducted to evaluate the performance of the proposed control protocol and the UDBA algorithm.The results show that,in comparison to the conventional DBA algorithm,the UDBA algorithm can utilize upstream bandwidth more efficiently to reduce packet delay and loss,without adversely impacting downstream transmission performance.
基金Project supported by Shandong Provincial Natural Science Foundation(Grant No.ZR2023LLZ003)the National Natural Science Foundation of China(Grant No.62005145)Fundamental Research Fund of Shandong University,and Shandong Provincial Postdoctoral Science Foundation(Grant No.SDBX202302002)。
文摘We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shift with variation of the detuning and power of the cooling laser and study the performance of the diffuse laser cooling mechanism by the absorption linewidth radio?ν_E/?ν_R and light shift|?_R-?_E|using nonlinear spectroscopy.Specifically,when?ν_E/?ν_R reaches a value of 1.57,the temperature and number of cold atoms achieve the optimal cooling effect.This characterization of absorption linewidth and light shift will provide a method to estimate whether diffuse light cooling achieves the best cooling effect,contributing to the future development of isotropic laser cooling for application in quantum sensing.
基金supported by the National Natural Science Foundation of China(62205180)the Natural Science Foundation of Shandong Province(ZR2022QF029)the Taishan Scholar Program of Shandong Province(Young Scientist).
文摘Semiconductor colloidal quantum wells(CQWs)with atomic-precision layer thickness are rapidly gaining attention for next-generation optoelectronic applications due to their tunable optical and electronic properties.In this study,we investigate the dielectric and optical characteristics of CdSe CQWs with monolayer numbers ranging from 2 to 7,synthesized via thermal injection and atomic layer(c-ALD)deposition techniques.Through a combination of spectroscopic ellipsometry(SE)and first-principles calculations,we demonstrate the significant tunability of the bandgap,refractive index,and extinction coefficient,driven by quantum confinement effects.Our results show a decrease in bandgap from 3.1 to 2.0 eV as the layer thickness increases.Furthermore,by employing a detailed analysis of the absorption spectra,accounting for exciton localization and asymmetric broadening,we precisely capture the relationship between monolayer number and exciton binding energy.These findings offer crucial insights for optimizing CdSe CQWs in optoelectronic device design by leveraging their layer-dependent properties.
文摘It is a pleasure to contribute a commentary on the very interesting review by Dr.Orcioli-Silva and colleagues1 on the simultaneous measurements of cerebral cortex and muscle tissue oxygenation during exercise in healthy adults using near-infrared spectroscopy(NIRS).The first NIRS measurements of the cerebral cortex and muscle were performed on humans in 19772 and 1982,3 respectively.
基金funded by the Vietnam Ministry of Education and Training(Project No.B2025 BKA-11).
文摘A novel low-coherence digital inline holographic microscope for accurate three-dimensional(3D)position estimation and nanoparticle classification is proposed and validated.Two low-coherence digital inline holograms of a sample containing numerous nanoparticles,generated by two illumination light beams forming a small angle with each other from a low-coherence light source,are employed to determine the nanoparticles’actual 3D positions.Each nanoparticle’s sub-holograms,extracted from the holograms of the sample,are used to reconstruct the intensity scattering image at its respective actual position using the Rayleigh–Sommerfeld backpropagation method.The intensity scattering image of each nanoparticle is then used to classify particles with similar sizes and shapes.The advantages of the proposed system include rapid and highly accurate 3D nanoparticle position determination and nanoparticle classification without the need to pre-prepare patterns or have prior knowledge of the nanoparticle characteristics.
基金supported by the College Students’ Innovation and Entrepreneurship Training Program (grant Nos.202410649025 and S202410649206)the Sichuan Science and Technology Program (grant No.2025Z NSFSC0315)+1 种基金the Key Laboratory of Detection and Application of Space Effect in Southwest Sichuan at Leshan Normal University,Education Department of Sichuan Province (grant No.ZDXM202401002)supported by National Astronomical Observatories,Chinese Academy of Sciences
文摘This study presents a detailed photometric and spectroscopic analysis of the W UMa-type binary NR Cam,using data from the Transiting Exoplanet Survey Satellite(TESS)and ground-based observations.The light curves exhibit significant variable,with a negative correlation between the brightness of the two maxima—a characteristic of W UMa-type binaries typically attributed to magnetic activity.To explain this behavior,we incorporated a starspot model into our Wilson–Devinney analysis.Our results confirm that NR Cam is a W-subtype,moderately contact binary with a low mass ratio of q=5.75(±0.03)and a fill-out factor of f=33.4(±3.1)%.We also analyzed the orbital period variation using all available times of minima.The resulting O−C diagram reveals a long-term decreasing trend in the orbital period at a rate of dP/dt=−5.18(±0.02)×10^(-8) day yr^(-1),superimposed with a periodic oscillation characterized by an amplitude of A_(3)=0.0019(±0.0001)day and an oscillation period of P_(3)=7.776(±0.003)yr.The long-term decrease is likely due to mass transfer between the binary components,with an estimated mass transfer rate of dM_(2)/dt=1.33(±0.01)×10^(-8)M_(⊙)yr^(-1).The periodic oscillations are likely driven by the light-travel time effect caused by a tertiary companion,with a minimum mass of M_(3)=0.0956(1)M_(⊙)and a maximum separation of 3.841(6)au.Additionally,we considered the possibility that the periodic variation could result from changes in the gravitational quadrupole moment due to magnetic activity cycles,as described by the Applegate mechanism.Our findings confirm that NR Cam is an active binary system,where magnetic activity plays a significant role in its orbital evolution.These results contribute to our understanding of the magnetic dynamics and evolutionary processes in contact binary systems.
基金supported by the National Natural Science Foundation of China(Nos.62175076,62105028,62475085)the Natural Science Foundation of Hubei Province of China(Nos.2024AFA016,2024AFB612)the Open Project Program of Hubei Optical Fundamental Research Center.
文摘The integrated waveguide polarizer is essential for photonic integrated circuits,and various designs of waveguide polarizers have been developed.As the demand for dense photonic integration increases rapidly,new strategies to minimize the device size are needed.In this paper,we have inversely designed an integrated transverse electric pass(TE-pass)polarizer with a footprint of 2.88μm×2.88μm,which is the smallest footprint ever achieved.A direct binary search algorithm is used to inversely design the device for maximizing the transverse electric(TE)transmission while minimizing transverse magnetic(TM)transmission.Finally,the inverse-designed device provides an average insertion loss of 0.99 dB and an average extinction ratio of 33 dB over a wavelength range of 100 nm.
基金supported by the DST-SERB,New Delhi,India (EMR/000228/2017)TEQIP-Ⅲ,Ministry of Education,Government of India。
文摘Cubic phase Tm^(3+)/Yb^(3+):Y_(2)O_(3) and Tm^(3+)/Yb^(3+)/Gd^(3+):Y_(2)O_(3) phosphors were prepared by low temperature combustion technique for upconversion emission in UV-visible range.The 980 nm excitation has generated UV emission at 314 nm in tridoped phosphor due to the energy transfer from Tm^(3+) to Gd^(3+)ion.Characteristic emission bands from Tm^(3+) are also observed in both the phosphors.Thermally coupled Stark sublevels ^(1)G_(4(a))(476 nm) and ^(1)G_(4(b))(488 nm) of Tm^(3+) ion were utilised for optical thermometry using fluorescent intensity ratio(FIR) method.The result shows that maximum absolute sensitivity in tridoped phosphor is observed to be 1.33 × 10^(-3) K^(-1) at 298 K.Moreover,temperature rise of phosphor at various pump power densities was also measured and it is estimated to achieve 407 K at the pump power density of 38.46 W/cm^(2).
文摘The laser-induced damage threshold(LIDT) of optical coating is a limited factor for development of a high peak power laser. The automatic damage testing facility was built to determine the LIDT of optics at 1 064 nm and 355 nm.. The cleanning and processing procedure of the substrate and coating technique were improved, and the damage resistance of high-reflective coating at 1 064 nm was increased.
基金supported by JSPS,MEXT,CORE(Center for Optical Research and Education,Utsunomiya University),ASHULA,ILE/Osaka University,and CDI(Cre-ative Department for Innovation,Utsunomiya University).
文摘In this review paper on heavy ion inertial fusion(HIF),the state-of-the-art scientific results are presented and discussed on the HIF physics,including physics of the heavy ion beam(HIB)transport in a fusion reactor,the HIBs-ion illumination on a direct-drive fuel target,the fuel target physics,the uniformity of the HIF target implosion,the smoothing mechanisms of the target implosion non-uniformity and the robust target implosion.The HIB has remarkable preferable features to release the fusion energy in inertial fusion:in particle accelerators HIBs are generated with a high driver efficiency of~30%-40%,and the HIB ions deposit their energy inside of materials.Therefore,a requirement for the fusion target energy gain is relatively low,that would be~50-70 to operate a HIF fusion reactor with the standard energy output of 1 GWof electricity.The HIF reactor operation frequency would be~10-15 Hz or so.Several-MJ HIBs illuminate a fusion fuel target,and the fuel target is imploded to about a thousand times of the solid density.Then the DT fuel is ignited and burned.The HIB ion deposition range is defined by the HIB ions stopping length,which would be~1 mm or so depending on the material.Therefore,a relatively large density-scale length appears in the fuel target material.One of the critical issues in inertial fusion would be a spherically uniform target compression,which would be degraded by a non-uniform implosion.The implosion non-uniformity would be introduced by the Rayleigh-Taylor(R-T)instability,and the large densitygradient-scale length helps to reduce the R-T growth rate.On the other hand,the large scale length of the HIB ions stopping range suggests that the temperature at the energy deposition layer in a HIF target does not reach a very-high temperature:normally about 300 eV or so is realized in the energy absorption region,and that a direct-drive target would be appropriate in HIF.In addition,the HIB accelerators are operated repetitively and stably.The precise control of the HIB axis manipulation is also realized in the HIF accelerator,and the HIB wobbling motion may give another tool to smooth the HIB illumination non-uniformity.The key issues in HIF physics are also discussed and presented in the paper.
基金Project supported by the National Natural Science Foundation of China(51872165)the Primary Research&Development Plan of Shandong Province(2019JZZY010313)。
文摘Disordered-structure crystals have drawn increasing attention as promising ultrashort laser material hosts owing to their broad linewidth.Herein,a novel disordered Nd:YSr_(3)(PO_(4))_(3)(Nd:YSP)crystal with good quality was successfully grown via the Czochralski pulling technique.The absorption and fluorescence spectra of the Nd:YSP single crystal were recorded at ambient temperature.The maximum absorption cross section for Nd:YSP single crystal is found to be approximately 3.89×10^(-20) cm^(2).The stimulated emission cross section for Nd:YSP crystal at~1060 nm was determined to be 7.64×10^(20) cm^(2) with the full width half maximum value of 22 nm.The fluorescence lifetime of the Nd3+ions in the Nd:YSP crystal is fitted to be 288μs.Diode-pumped continuous-wave laser operation is firstly realized at approximately 1060 nm.The maximum output power value from the Nd:YSP crystal is 714 mW,corresponding to a slope efficiency of-12.8%.The results indicate that the Nd:YSP crystal with a disordered structure may be a promising disordered laser host.
基金Supported by the Fund of Key Laboratory of Crystal Material of Shandong University under Grant No KF1101the Fund of Shandong University under Grant No 11170072613176.
文摘An efficient dual-wavelength laser-diode-pumped Nd:YAG ceramic laser operating at 1112 and 1116 nm is demonstrated.We obtain a maximum total output power of 3.43 W including a 1.77 W 1112 nm component and a 1.66 W 1116 nm component under a pump power of 16.1 W,corresponding to a slope efficiency of 23.7%and a total optical-to-optical efficiency of 21.3%.
文摘In close-aperture Z-scan experiments, a small aperture is conventionally located in the far-field thereby enabling the detection of slight changes in the laser beam profile due to the Kerr-lensing effect. In this work, by numerically solving the Fresnel-Kirchhoff diffraction integrals, the amount of transmitted power through apertures has been evaluated and a parametric study on the role of the various parameters that can influence this transmitted power has been done. In order to perform a comprehensive analysis, we have used a nonlinear phase shift optimized for nonlocal nonlinear media in our calculations. Our results show that apertures will result in the formation of symmetrical fluctuations on the wings of Z-scan transmittance curves. It is further shown that the appearance of these fluctuations can be ascribed to the natural diffraction of the Gaussian beam as it propagates up to the aperture plane. Our calculations reveal that the nonlocal parameter variations can shift the position of fluctuations along the optical axis, whereas their magnitude depends on the largeness of the induced nonlinear phase shift. It is concluded that since the mentioned fluctuations are produced by the natural diffraction of the Gaussian beam itself, one must take care not to mistakenly interpret them as noise and should not expect to eliminate them from experimental Z-scan transmittance curves by using apertures with different sizes.
基金National Science Foundation of China(NSFC)(61871082 and 62111530150)Fundamental Research Funds for the Central Universities(ZYGX2020ZB043 and ZYGX2019J008).
文摘As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service experience.With the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and back-haul.Optical access networks would play an important role in F5G to support radio access network and fixed access network.Low-latency PON is a key for cost effective-haul traffic aggregation.In terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple architecture.The fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s phase.In access network,the flexibility and low latency are the two key factors affecting service experience.In this article,we review the evolution of PONs and the challenges of current PONs in detail.We analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU communications.Finally,we discuss the developing trends of future optical access networks.
文摘One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wutzite phase （hexagonal structure）. SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods （sulfur precursor： Na2S） was shown blue shift to 485 nm due to the quantum size effect.
文摘Ultrafine Y（OH）3 nanoparticles were successfully deposited from an additive-free 0.005 mol/L YCl3 low-temperature bath on the steel cathode at the current density of 0.5 mA/cm2 and bath temperature of 10 oC. Heat treatment of the prepared Y（OH）3 nanoparticles at 600 oC in air led to the formation of Y2O3 nanoparticles. Thermal behavior and phase transformation during the heat treatment of Y（OH）3 were investigated by differential scanning calorimetry （DSC） and thermogramimetric analysis （TGA）. The morphologies, crystal structures and compositions of the prepared materials were examined by means of scanning and transmission electron microscopy （SEM and TEM） as well as X-ray diffraction （XRD） and FT-IR spectroscopy. The results showed that the prepared Y（OH）3 nanoparticles was essentially amorphous and composed of well dispersed ultrafine particles with size of 4 nm. After heat treatment, the obtained oxide product was well crystallized cubic phase of Y2O3 nanoparticles with the grain size of around 5 nm. It was concluded that low-temperature cathodic electrodeposition offered a facile and feasible way for preparation of ultrafine Y（OH）3 and Y2O3 nanoparticles.
