Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are co...Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are connected via both a quantum channel and a classical authentication channel.This paper presents a comprehensive overview of QKD protocols,chip-based QKD systems,quantum light sources,quantum detectors,fiber-based QKD networks,space-based QKD systems,as well as the applications and prospects of QKD technology.展开更多
Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalab...Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalability.However,waveguide stresses,both intrinsic and temperature-induced stresses,have significant impacts on the stable operation of the system.We have designed silica AMZI chips of 400 ps delay,with bend waveguides length equalized for both long and short arms to balance the stresses thereof.The temperature characteristics of the silica PLC AMZI chip are studied.The interference visibility at the single photon level is kept higher than 95%over a wide temperature range of 12℃.The delay time change is 0.321 ps within a temperature change of 40℃.The spectral shift is 0.0011 nm/0.1℃.Temperature-induced delay time and peak wavelength variations do not affect the interference visibility.The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.展开更多
In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-...In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-Ga_(2)O_(3) film with full width at half maximum(FWHM)of 0.66°was achieved.A metal−semiconductor−metal(MSM)solar-blind photodetector(PD)was fabricated based on theβ-Ga_(2)O_(3) film.Ultrahigh responsivity of 1422 A/W@254 nm and photo-to-dark current ratio(PDCR)of 10^(6) at 10 V bias were obtained.The detectivity of 2.5×10^(15) Jones proved that the photodetector has outstanding performance in detecting weak signals.Moreover,the photodetector exhibited superior wavelength selectivity with rejection ratio(R_(250 nm)/R_(400 nm))of 105.These results indicate that the two-step method is a promising approach for preparation of high-qualityβ-Ga_(2)O_(3)films for high-performance solar-blind photodetectors.展开更多
A compact structured illumination chip based on integrated optics is proposed and fabricated on a silicon-oninsulator platform.Based on the simulation of Gaussian beam interference,we adopt a chirped diffraction grati...A compact structured illumination chip based on integrated optics is proposed and fabricated on a silicon-oninsulator platform.Based on the simulation of Gaussian beam interference,we adopt a chirped diffraction grating to achieve a specific interference pattern.The experimental results match well with the simulations.The portability and flexibility of the structured illumination chip can be increased greatly through horizontal encapsulation.High levels of integration,compared with the conventional structured illumination approach,make this chip very compact,with a footprint of only around 1 mm^2.The chip has no optical lenses and can be easily combined with a microfluidic system.These properties would make the chip very suitable for portable 3D scanner and compact super-resolution microscopy applications.展开更多
For the frequency range of 1 kHz-10 MHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage(C-V) and conductance-frequency-voltage(G-f-V) measurements at room temperature.To obtai...For the frequency range of 1 kHz-10 MHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage(C-V) and conductance-frequency-voltage(G-f-V) measurements at room temperature.To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance(R_s) on high-frequency(5 MHz) capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the C_(HF)-C_(LF) capacitance and the conductance method are 2 ×10^(12) eV^(-1)cm^(-2) and 0.94 ×10^(12) eV^(-1) cm^(-2), respectively. Furthermore, the interface state densit.y derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.展开更多
Step-coupler waveguide-integrated Ge/Si avalanche photodetector(APD) is based on the vertical multimode interference(MMI), enhancing light scattering towards the Ge active region and creating mirror images of optical ...Step-coupler waveguide-integrated Ge/Si avalanche photodetector(APD) is based on the vertical multimode interference(MMI), enhancing light scattering towards the Ge active region and creating mirror images of optical modes close to the Ge layer. However, there are two ineluctable contact angels between selectively epitaxial growth Ge and Si layers and selectively epitaxial growth Si and Si substrate, which has an effect on the coupling efficiency and the absorption of the photodetector. Therefore, step-coupled Ge/Si avalanche photodetectors with different step lengths are designed and fabricated. It is found that responsivity of APDs with step-coupler-length of 3.0 μm is 0.51 A/W at-6 V, 21% higher than that of 1.5 μm, which matches well with simulation absorption. The multiplication gain factor is as high as 50, and the maximum gain-bandwidth product reaches up to 376 GHz.展开更多
In this paper,we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency.High responsivity (> 1 A/W),high s...In this paper,we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency.High responsivity (> 1 A/W),high saturation power (> 45 mA) in the static state and extremely low dark current density (0.04 pA/μm 2) with 3 dB bandwidth at 13.4 GHz have been achieved.展开更多
The local density of states (LDOS) of two-dimensional square lattice photonic crystal (PhC) defect cavity is studied.The results show that the LDOS in the centre is greatly reduced,while the LDOS at the point off the ...The local density of states (LDOS) of two-dimensional square lattice photonic crystal (PhC) defect cavity is studied.The results show that the LDOS in the centre is greatly reduced,while the LDOS at the point off the centre (for example,at the point (0.3a,0.4a),where a is the lattice constant) is extremely enhanced.Further,the disordered radii are introduced to imitate the real devices fabricated in our experiment,and then we study the LDOS of PhC cavity with configurations of different disordered radii.The results show that in the disordered cavity,the LDOS in the centre is still greatly reduced,while the LDOS at the point (0.3a,0.4a) is still extremely enhanced.It shows that the LDOS analysis is useful.When a laser is designed on the basis of the square lattice PhC rod cavity,in order to enhance the spontaneous emission,the active materials should not be inserted in the centre of the cavity,but located at positions off the centre.So LDOS method gives a guide to design the positions of the active materials (quantum dots) in the lasers.展开更多
We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simulations using the three-dimensional finite-difference time-domain method show that the novel elliptical mic...We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simulations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.展开更多
We experimentally and numerically investigate CH_3I molecular alignment by using a femtosecond laser and a hexapole. The hexapole provides the single |111〉rotational state condition at 4.5-kV hexapole rod voltage. Ba...We experimentally and numerically investigate CH_3I molecular alignment by using a femtosecond laser and a hexapole. The hexapole provides the single |111〉rotational state condition at 4.5-kV hexapole rod voltage. Based on this single rotational state, an enhanced alignment degree of 0.73 is achieved. Our experimental results are in agreement with the simulation results. We experimentally obtain the ion velocity map images and show the influence of the initial rotational-state population. With the I+ion images and angular distributions at different pump-probe delay time, the alignment and anti-alignment phenomena are further demonstrated. The molecules will be under field-free conditions when the laser effect disappears completely at the full revival time. Our work shows that the quantum control and spatial control on CH_3I molecules can be realized and molecular coordinate frame can be obtained for further molecular experiment.展开更多
新奇 Y 分支由捆的方法与一根超级光二极管基于整体的收发器，一根波导光电二极管(Y-SDL-PD ) 被设计并且制作综合波导(大) 作为为整体的集成和 angled Y 分支的计划作为被动双向波导。模拟大并且 Y 分支表演低损失和改进远地的模式，...新奇 Y 分支由捆的方法与一根超级光二极管基于整体的收发器，一根波导光电二极管(Y-SDL-PD ) 被设计并且制作综合波导(大) 作为为整体的集成和 angled Y 分支的计划作为被动双向波导。模拟大并且 Y 分支表演低损失和改进远地的模式，基于横梁繁殖方法(BPM ) 。设备的放大自发的排放直到在没有阀值和浸透的 120 妈的 10 mW。光谱大约 30 nm 宽度和不到 1 dB 调整的特征用 Y 分支的内建的放射激光反的能力被完成。在水平、垂直的方向的横梁分叉角度被优化，导致联合的好纤维象 12 °×一样小 8 °。展开更多
The ionization processes of NH3 molecule are studied by photoelectron velocity map imaging technique in a linearly polarized 400-nm femtosecond laser field. The two-dimensional photoelectron images from ammonia molecu...The ionization processes of NH3 molecule are studied by photoelectron velocity map imaging technique in a linearly polarized 400-nm femtosecond laser field. The two-dimensional photoelectron images from ammonia molecules under different laser intensities are obtained. In the slow electron region, the values of kinetic energy of photoelectrons corresponding to peaks 1, 2, 3, and 4 are 0.27, 0.86, 1.16, and 1.6 eV, respectively. With both the kinetic energy and angular distribution of photoelectrons from NH3 molecules, we can confirm that the two-photon excited intermediate Rydberg state is A^1 A2" (v2'=3) state for photoelectron peaks 2, 3, 4, and the three peaks are marked as 1223 (2 + 2), 1123 (2 + 2), and 1023 (2 + 2) multi-photon processes, respectively. Then, peak 1 is found by adding a hexapole between the source chamber and the detection chamber to realize the rotational state selection and beam focusing. Peak 1 is labeled as the 1323 (3 + 1) multi-photon process through the intermediate Rydberg state E^1A1'. The phenomena of channel switching are found in the slow electron kinetic energy distributions. Our calculations and experimental results indicate that the stretching vibrational mode of ammonia molecules varies with channels, while the umbrella vibration does not. In addition, we consider and discuss the ac-Stark effect in a strong laser field. Peaks 5 and 6 are marked as (2 + 2 + 1) and (2 + 2 + 2) above threshold ionization processes in the fast electron region.展开更多
A quantum key distribution transmitter chip based on hybrid-integration of silica planar light-wave circuit(PLC)and lithium niobates(LN)modulator PLC is presented.The silica part consists of a tunable directional coup...A quantum key distribution transmitter chip based on hybrid-integration of silica planar light-wave circuit(PLC)and lithium niobates(LN)modulator PLC is presented.The silica part consists of a tunable directional coupler and 400-ps delay line,and the LN part is made up of a Y-branch,with electro-optic modulators on both arms.The two parts are facet-coupled to form an asymmetric Mach-Zehnder interferometer.We successfully encode and decode four BB84 states at 156.25-MHz repetition rate.Fast phase-encoding of 0 orπis achieved,with interference fringe visibilities 78.53%and 82.68%for states|+〉and|-〉,respectively.With the aid of an extra off-chip LN intensity modulator,two time-bin states are prepared and the extinction ratios are 18.65 dB and 15.46 dB for states|0〉and|1〉,respectively.展开更多
Considering the effects of increased economic globalization and global warming,developing methods for reducing shipping costs and greenhouse gas emissions in ocean transportation has become crucial.Owing to its key ro...Considering the effects of increased economic globalization and global warming,developing methods for reducing shipping costs and greenhouse gas emissions in ocean transportation has become crucial.Owing to its key role in modern navigation technology,ship weather routing is the research focus of several scholars in this field.This study presents a hybrid genetic algorithm for the design of an optimal ship route for safe transoceanic navigation under complicated sea conditions.On the basis of the basic genetic algorithm,simulated annealing algorithm is introduced to enhance its local search ability and avoid premature convergence,with the ship’s voyage time and fuel consumption as optimization goals.Then,a mathematical model of ship weather routing is developed based on the grid system.A measure of fitness calibration is proposed,which can change the selection pressure of the algorithm as the population evolves.In addition,a hybrid crossover operator is proposed to enhance the ability to find the optimal solution and accelerate the convergence speed of the algorithm.Finally,a multi-population technique is applied to improve the robustness of the algorithm using different evolutionary strategies.展开更多
The local density of optical states(LDOS)is an important physical concept,which can characterize the spontaneous emission of microcavities.In order to calculate the LDOS,the relationship between the mode spectrum and ...The local density of optical states(LDOS)is an important physical concept,which can characterize the spontaneous emission of microcavities.In order to calculate the LDOS,the relationship between the mode spectrum and the LDOS is established.Then,based on the transfer matrix method and the effective resonator model,the leaky loss of the leaky mode and the mode spectrum in the one-dimensional photonic bandgap crystal waveguide are calculated,results of which indicate that the mode spectrum can characterize the leaky loss of the leaky mode.At last,the density of optical states(DOS),and the LDOS in each layer are calculated.The partial DOS and the partial LDOS in the quantum well,related to the fundamental leaky mode,can be used to find out the optimal location of the quantum well in the defect layer to couple more useful photons into the lasing mode for lasers.展开更多
Since 2020,the global outbreak and continued evolution of the COVID-19 pandemic have brought the concepts of nucleic acid,antigen-antibody,gene sequencing,and other biochemical testing into ordinary families.In this r...Since 2020,the global outbreak and continued evolution of the COVID-19 pandemic have brought the concepts of nucleic acid,antigen-antibody,gene sequencing,and other biochemical testing into ordinary families.In this regard,novel semiconductor-biochemical sensors that convert biochemical information into monitorable electrical and optical signals according to specific rules have become increasingly important and indispensable.These sensors deeply fuse the technical advantages of semiconductors and biochemistry,integrating interdisciplinary subjects such as molecular biology,nanomaterials,microfluidics,artificial intelligence(AI),etc.With the advantages of fast speed,high sensitivity,high integration,easy mass manufacturing,the novel technologies are the"pioneer"of biomedical information acquisition and the"heart"of modern medical diagnostic equipment.Currently,the technologies are showing a spurt of development,with new products emerging,new functions being developed,and new application scenarios being expanded.The research hotspots cover a wide range,including immediate detection,non-invasive analysis,wearable devices,on-site monitoring,etc.This issue looks at the latest advances in the novel technologies for physiological dynamic monitoring of animals/plants and rapid detection of highly pathogenic pathogens,while covering applications in agriculture,fisheries,animal husbandry,biosecurity,and wearable medicine.展开更多
In the past few years,many groups have focused on the research and development of GaN-based ultraviolet laser diodes(UV LDs).Great progresses have been achieved even though many challenges exist.In this article,we ana...In the past few years,many groups have focused on the research and development of GaN-based ultraviolet laser diodes(UV LDs).Great progresses have been achieved even though many challenges exist.In this article,we analyze the challenges of developing GaN-based ultraviolet laser diodes,and the approaches to improve the performance of ultraviolet laser diode are reviewed.With these techniques,room temperature(RT)pulsed oscillation of AlGaN UVA(ultraviolet A)LD has been realized,with a lasing wavelength of 357.9 nm.Combining with the suppression of thermal effect,the high output power of 3.8 W UV LD with a lasing wavelength of 386.5 nm was also fabricated.展开更多
Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.I...Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.展开更多
基金Project supported by the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0300701)the National Key Research and Development Program of China (Grant No.2018YFA0306403)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB43000000)。
文摘Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are connected via both a quantum channel and a classical authentication channel.This paper presents a comprehensive overview of QKD protocols,chip-based QKD systems,quantum light sources,quantum detectors,fiber-based QKD networks,space-based QKD systems,as well as the applications and prospects of QKD technology.
基金Project supported by the National Key R&D Program of China (Grant No.2018YFA0306403)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB43000000)+1 种基金Innovation Program for Quantum Science and TechnologyComputer Interconnect Technology Alliance Funding (Grant No.20220103)。
文摘Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalability.However,waveguide stresses,both intrinsic and temperature-induced stresses,have significant impacts on the stable operation of the system.We have designed silica AMZI chips of 400 ps delay,with bend waveguides length equalized for both long and short arms to balance the stresses thereof.The temperature characteristics of the silica PLC AMZI chip are studied.The interference visibility at the single photon level is kept higher than 95%over a wide temperature range of 12℃.The delay time change is 0.321 ps within a temperature change of 40℃.The spectral shift is 0.0011 nm/0.1℃.Temperature-induced delay time and peak wavelength variations do not affect the interference visibility.The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2020YFB2206103)。
文摘In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-Ga_(2)O_(3) film with full width at half maximum(FWHM)of 0.66°was achieved.A metal−semiconductor−metal(MSM)solar-blind photodetector(PD)was fabricated based on theβ-Ga_(2)O_(3) film.Ultrahigh responsivity of 1422 A/W@254 nm and photo-to-dark current ratio(PDCR)of 10^(6) at 10 V bias were obtained.The detectivity of 2.5×10^(15) Jones proved that the photodetector has outstanding performance in detecting weak signals.Moreover,the photodetector exhibited superior wavelength selectivity with rejection ratio(R_(250 nm)/R_(400 nm))of 105.These results indicate that the two-step method is a promising approach for preparation of high-qualityβ-Ga_(2)O_(3)films for high-performance solar-blind photodetectors.
基金Supported by the National Natural Science Foundation of China under Grant No 61334008the National High-Technology Research and Development Program of China under Grant No 2015AA016904the Instrument Developing Project of the Chinese Academy of Sciences under Grant No YZ201301
文摘A compact structured illumination chip based on integrated optics is proposed and fabricated on a silicon-oninsulator platform.Based on the simulation of Gaussian beam interference,we adopt a chirped diffraction grating to achieve a specific interference pattern.The experimental results match well with the simulations.The portability and flexibility of the structured illumination chip can be increased greatly through horizontal encapsulation.High levels of integration,compared with the conventional structured illumination approach,make this chip very compact,with a footprint of only around 1 mm^2.The chip has no optical lenses and can be easily combined with a microfluidic system.These properties would make the chip very suitable for portable 3D scanner and compact super-resolution microscopy applications.
基金Supported by the Natural Science Foundation of Jiangxi Province under Grant No 20133ACB20005the Key Program of National Natural Science Foundation of China under Grant No 41330318+3 种基金the Key Program of Science and Technology Research of Ministry of Education under Grant No NRE1515the Foundation of Training Academic and Technical Leaders for Main Majors of Jiangxi Province under Grant No 20142BCB22006the Research Foundation of Education Bureau of Jiangxi Province under Grant No GJJ14501the Engineering Research Center of Nuclear Technology Application(East China Institute of Technology)Ministry of Education under Grant NoHJSJYB2016-1
文摘For the frequency range of 1 kHz-10 MHz, the interface state density of Ni contacts on p-GaN is studied using capacitance-voltage(C-V) and conductance-frequency-voltage(G-f-V) measurements at room temperature.To obtain the real capacitance and interface state density of the Ni/p-GaN structures, the effects of the series resistance(R_s) on high-frequency(5 MHz) capacitance values measured at a reverse and a forward bias are investigated. The mean interface state densities obtained from the C_(HF)-C_(LF) capacitance and the conductance method are 2 ×10^(12) eV^(-1)cm^(-2) and 0.94 ×10^(12) eV^(-1) cm^(-2), respectively. Furthermore, the interface state densit.y derived from the conductance method is higher than that reported from the Ni/n-GaN in the literature, which is ascribed to a poor crystal quality and to a large defect density of the Mg-doped p-GaN.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFB0402502 and 2017YFF0104803)the National Natural Science Foundation of China(Grant Nos.61674140 and 61505003)+2 种基金the Beijing Natural Science Foundation,China(Grant No.4162063)Beijing Education Commission Project(Grant No.SQKM201610005008)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC022)
文摘Step-coupler waveguide-integrated Ge/Si avalanche photodetector(APD) is based on the vertical multimode interference(MMI), enhancing light scattering towards the Ge active region and creating mirror images of optical modes close to the Ge layer. However, there are two ineluctable contact angels between selectively epitaxial growth Ge and Si layers and selectively epitaxial growth Si and Si substrate, which has an effect on the coupling efficiency and the absorption of the photodetector. Therefore, step-coupled Ge/Si avalanche photodetectors with different step lengths are designed and fabricated. It is found that responsivity of APDs with step-coupler-length of 3.0 μm is 0.51 A/W at-6 V, 21% higher than that of 1.5 μm, which matches well with simulation absorption. The multiplication gain factor is as high as 50, and the maximum gain-bandwidth product reaches up to 376 GHz.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006CB302802)
文摘In this paper,we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency.High responsivity (> 1 A/W),high saturation power (> 45 mA) in the static state and extremely low dark current density (0.04 pA/μm 2) with 3 dB bandwidth at 13.4 GHz have been achieved.
基金Supported in part by the National High-Tech Research and Development Program of China under Grant Nos 2007AA03Z417, 2006AA01Z256 and 2007AA03Z419, the National Basic Research Program of China under Grant Nos 2006CB604901 and 2006CB604902, and the National Natural Science Foundation of China under Grant Nos 90401025, 60736036, 60706009 and 60777021. We would like to thank Fan Zhou, Jiaoqing Pan, Huiyun Shu and Baojun Wang for their help in the experiment, and Lufeng Wang, Jing Bian, Xin An for their support on the device test.
基金Supported by the State Key Development Program for Basic Research of China under Grant No 2006CB302803, and the National Natural Science Foundation of China under Grant No 60877036.
基金supported by the National Basic Research Program of China (Grant No. 2006CB921705)the National Natural Science Foundation of China (Grant Nos. 10634080,60677046 and 60838003)the National High Technology Research and Development Program of China (Grant Nos. 2007AA03Z410 and 2007AA03Z408)
文摘The local density of states (LDOS) of two-dimensional square lattice photonic crystal (PhC) defect cavity is studied.The results show that the LDOS in the centre is greatly reduced,while the LDOS at the point off the centre (for example,at the point (0.3a,0.4a),where a is the lattice constant) is extremely enhanced.Further,the disordered radii are introduced to imitate the real devices fabricated in our experiment,and then we study the LDOS of PhC cavity with configurations of different disordered radii.The results show that in the disordered cavity,the LDOS in the centre is still greatly reduced,while the LDOS at the point (0.3a,0.4a) is still extremely enhanced.It shows that the LDOS analysis is useful.When a laser is designed on the basis of the square lattice PhC rod cavity,in order to enhance the spontaneous emission,the active materials should not be inserted in the centre of the cavity,but located at positions off the centre.So LDOS method gives a guide to design the positions of the active materials (quantum dots) in the lasers.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB301701, 2012CB933502, and2012CB933504)the National Natural Science Foundation of China (Grant Nos. 60877036 and 61107048)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX2-EW-102)
文摘We propose a novel resonator containing an elliptical microring based on a silicon-on-insulator platform. Simulations using the three-dimensional finite-difference time-domain method show that the novel elliptical microring can efficiently enhance the mode coupling between straight bus waveguides and resonator waveguides or between adjacent resonators while preserving relatively high intrinsic quality factors with large free spectral range. The proposed resonator would be an alternative choice for future high-density integrated photonic circuits.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574116,11534004,10704028,and 11474123)the Natural Science Foundation of Jilin Province,China(Grant No.20170101154JC)
文摘We experimentally and numerically investigate CH_3I molecular alignment by using a femtosecond laser and a hexapole. The hexapole provides the single |111〉rotational state condition at 4.5-kV hexapole rod voltage. Based on this single rotational state, an enhanced alignment degree of 0.73 is achieved. Our experimental results are in agreement with the simulation results. We experimentally obtain the ion velocity map images and show the influence of the initial rotational-state population. With the I+ion images and angular distributions at different pump-probe delay time, the alignment and anti-alignment phenomena are further demonstrated. The molecules will be under field-free conditions when the laser effect disappears completely at the full revival time. Our work shows that the quantum control and spatial control on CH_3I molecules can be realized and molecular coordinate frame can be obtained for further molecular experiment.
基金Supported by the National Natural Science Foundation of China under Grant Nos 90401025 and 60476009, and the National Basic Research Programme of China under Grant Nos 2006CB604901 and 2006CB604902, and the National High-Tech R＆D Programme of China under Grant No 2006AA01Z256.
文摘新奇 Y 分支由捆的方法与一根超级光二极管基于整体的收发器，一根波导光电二极管(Y-SDL-PD ) 被设计并且制作综合波导(大) 作为为整体的集成和 angled Y 分支的计划作为被动双向波导。模拟大并且 Y 分支表演低损失和改进远地的模式，基于横梁繁殖方法(BPM ) 。设备的放大自发的排放直到在没有阀值和浸透的 120 妈的 10 mW。光谱大约 30 nm 宽度和不到 1 dB 调整的特征用 Y 分支的内建的放射激光反的能力被完成。在水平、垂直的方向的横梁分叉角度被优化，导致联合的好纤维象 12 °×一样小 8 °。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11574116, 11534004, and 10704028).
文摘The ionization processes of NH3 molecule are studied by photoelectron velocity map imaging technique in a linearly polarized 400-nm femtosecond laser field. The two-dimensional photoelectron images from ammonia molecules under different laser intensities are obtained. In the slow electron region, the values of kinetic energy of photoelectrons corresponding to peaks 1, 2, 3, and 4 are 0.27, 0.86, 1.16, and 1.6 eV, respectively. With both the kinetic energy and angular distribution of photoelectrons from NH3 molecules, we can confirm that the two-photon excited intermediate Rydberg state is A^1 A2" (v2'=3) state for photoelectron peaks 2, 3, 4, and the three peaks are marked as 1223 (2 + 2), 1123 (2 + 2), and 1023 (2 + 2) multi-photon processes, respectively. Then, peak 1 is found by adding a hexapole between the source chamber and the detection chamber to realize the rotational state selection and beam focusing. Peak 1 is labeled as the 1323 (3 + 1) multi-photon process through the intermediate Rydberg state E^1A1'. The phenomena of channel switching are found in the slow electron kinetic energy distributions. Our calculations and experimental results indicate that the stretching vibrational mode of ammonia molecules varies with channels, while the umbrella vibration does not. In addition, we consider and discuss the ac-Stark effect in a strong laser field. Peaks 5 and 6 are marked as (2 + 2 + 1) and (2 + 2 + 2) above threshold ionization processes in the fast electron region.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0306403)the National Natural Science Foundation of China(Grant Nos.61435013 and 61627820)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB43000000)the K.C.Wong Education Foundation,Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY030000)。
文摘A quantum key distribution transmitter chip based on hybrid-integration of silica planar light-wave circuit(PLC)and lithium niobates(LN)modulator PLC is presented.The silica part consists of a tunable directional coupler and 400-ps delay line,and the LN part is made up of a Y-branch,with electro-optic modulators on both arms.The two parts are facet-coupled to form an asymmetric Mach-Zehnder interferometer.We successfully encode and decode four BB84 states at 156.25-MHz repetition rate.Fast phase-encoding of 0 orπis achieved,with interference fringe visibilities 78.53%and 82.68%for states|+〉and|-〉,respectively.With the aid of an extra off-chip LN intensity modulator,two time-bin states are prepared and the extinction ratios are 18.65 dB and 15.46 dB for states|0〉and|1〉,respectively.
基金funded by the Russian Foundation for Basic Research(RFBR)(No.20-07-00531).
文摘Considering the effects of increased economic globalization and global warming,developing methods for reducing shipping costs and greenhouse gas emissions in ocean transportation has become crucial.Owing to its key role in modern navigation technology,ship weather routing is the research focus of several scholars in this field.This study presents a hybrid genetic algorithm for the design of an optimal ship route for safe transoceanic navigation under complicated sea conditions.On the basis of the basic genetic algorithm,simulated annealing algorithm is introduced to enhance its local search ability and avoid premature convergence,with the ship’s voyage time and fuel consumption as optimization goals.Then,a mathematical model of ship weather routing is developed based on the grid system.A measure of fitness calibration is proposed,which can change the selection pressure of the algorithm as the population evolves.In addition,a hybrid crossover operator is proposed to enhance the ability to find the optimal solution and accelerate the convergence speed of the algorithm.Finally,a multi-population technique is applied to improve the robustness of the algorithm using different evolutionary strategies.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400604 and 2021YFB2801400)the National Natural Science Foundation of China(Grant Nos.91850206,62075213,62135001,and 62205328)。
文摘The local density of optical states(LDOS)is an important physical concept,which can characterize the spontaneous emission of microcavities.In order to calculate the LDOS,the relationship between the mode spectrum and the LDOS is established.Then,based on the transfer matrix method and the effective resonator model,the leaky loss of the leaky mode and the mode spectrum in the one-dimensional photonic bandgap crystal waveguide are calculated,results of which indicate that the mode spectrum can characterize the leaky loss of the leaky mode.At last,the density of optical states(DOS),and the LDOS in each layer are calculated.The partial DOS and the partial LDOS in the quantum well,related to the fundamental leaky mode,can be used to find out the optimal location of the quantum well in the defect layer to couple more useful photons into the lasing mode for lasers.
文摘Since 2020,the global outbreak and continued evolution of the COVID-19 pandemic have brought the concepts of nucleic acid,antigen-antibody,gene sequencing,and other biochemical testing into ordinary families.In this regard,novel semiconductor-biochemical sensors that convert biochemical information into monitorable electrical and optical signals according to specific rules have become increasingly important and indispensable.These sensors deeply fuse the technical advantages of semiconductors and biochemistry,integrating interdisciplinary subjects such as molecular biology,nanomaterials,microfluidics,artificial intelligence(AI),etc.With the advantages of fast speed,high sensitivity,high integration,easy mass manufacturing,the novel technologies are the"pioneer"of biomedical information acquisition and the"heart"of modern medical diagnostic equipment.Currently,the technologies are showing a spurt of development,with new products emerging,new functions being developed,and new application scenarios being expanded.The research hotspots cover a wide range,including immediate detection,non-invasive analysis,wearable devices,on-site monitoring,etc.This issue looks at the latest advances in the novel technologies for physiological dynamic monitoring of animals/plants and rapid detection of highly pathogenic pathogens,while covering applications in agriculture,fisheries,animal husbandry,biosecurity,and wearable medicine.
基金This work was supported by the National Key R&D Program of China(2022YFB3605104)National Natural Science Foundation of China(62250038,61904172,61974162,62034008,62074142,and 62074140)+1 种基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB43030101)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SX-TD016).
文摘In the past few years,many groups have focused on the research and development of GaN-based ultraviolet laser diodes(UV LDs).Great progresses have been achieved even though many challenges exist.In this article,we analyze the challenges of developing GaN-based ultraviolet laser diodes,and the approaches to improve the performance of ultraviolet laser diode are reviewed.With these techniques,room temperature(RT)pulsed oscillation of AlGaN UVA(ultraviolet A)LD has been realized,with a lasing wavelength of 357.9 nm.Combining with the suppression of thermal effect,the high output power of 3.8 W UV LD with a lasing wavelength of 386.5 nm was also fabricated.
基金National Key Research and Development Program of China(2021YFA1400602)National Natural Science Foundation of China(11974261,62075213,12104105,12274325,11874286,61621001,91850206)。
文摘Metasurfaces with spin-selective transmission play an increasingly critical role in realizing optical chiral responses,especially for strong intrinsic chirality,which is limited to complex three-dimensional geometry.In this paper,we propose a planar metasurface capable of generating maximal intrinsic chirality and achieving dual-band spinselective transmission utilizing dual quasi-bound states in the continuum(quasi-BICs)caused by the structural symmetry breaking.Interestingly,the value of circular dichroism(CD)and the transmittance of two kinds of circular polarization states can be arbitrarily controlled by tuning the asymmetry parameter.Remarkable CD approaching unity with the maximum transmittance up to 0.95 is experimentally achieved in the dual band.Furthermore,assisted by chiral BICs,the application in polarization multiplexed near-field image display is also exhibited.Our work provides a new avenue to flexibly control intrinsic chirality in planar structure and offers an alternative strategy to develop chiral sensing,multiband spin-selective transmission,and high-performance circularly polarized wave detection.The basic principle and design method of our experiments in the microwave regime can be extended to other bands,such as the terahertz and infrared wavelengths.
