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Optimal preparation of Bose and Fermi atomic gas mixtures of ^(87)Rb and ^(40)K in a crossed optical dipole trap

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Chinese Physics B 2024年第6期33卷 356-361页

作者：丁培波单标赵宇航杨雅婧陈良超孟增明王鹏军黄良辉 State key laboratory of Quantum optics and Quantum optics Devices Institute of Opto-electronicsCollaborative Innovation Center of Extreme OpticsShanxi UniversityTaiyuan 030006China Hefei National laboratory Hefei 230000China

We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin state |F=9/2,m_(F)=9/2> of^(40)K and |1,1>of ^(87) Rb in the ODT,which is larger and longer compared with the combination of the spin state |9/2,9/2> of^(40)K and 12,2) of ^(87)Rb in the *** observe the atomic numbers of ^(87)Rb and ^(40)K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical *** optimizing the relative loading time of atomic mixtures in the MOT,we obtain the large atomic number of ^(40)K(~6 ×10^(6)) or the mixtures of atoms with an equal number(~1.6 × 10^(6)) at the end of evaporative cooling in the *** experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms(8 × 10^(6)) and higher degeneracy(T/T_(F)=0.25) of Fermi gases are *** ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model,as well as for creating ground-state molecules of ^(87)Rb^(40)K.

关键词： optical dipole trap Bose and Fermi gas mixtures atomic lifetime

Spectral-interferometry-based diff-iteration for high-precision micro-dispersion measurement

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Photonics Research 2024年第6期12卷 1362-1370页

作者： WEI DU JINGSHENG HUANG YANG WANG MAOZHONG ZHAO JUAN LI JUNTAO HE JINDONG WANG WENFU ZHANG TAO ZHU key laboratory of Optoelectronic Technology&System(Ministry of Education) Chongqing UniversityChongqing 400044China State key laboratory of Transient optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi’an 710119China

Precise measurement of micro-dispersion for optical devices(optical fiber,lenses,etc.)holds paramount significance across domains such as optical fiber communication and dispersion interference ***,due to its complex system,complicated process,and low reliability,the traditional dispersion measurement methods(interference,phase shift,or time delay methods)are not suitable for the accurate measurement of micro-dispersion in a wide spectral ***,we propose a spectral-interferometry-based diff-iteration(SiDi)method for achieving accurate wide-band micro-dispersion *** an optical frequency comb,based on the phase demodulation of the dispersion interference spectrum,we employ the carefully designed SiDi method to solve the dispersion curve at any position and any *** approach is proficient in precisely measuring micro-dispersion across a broadband spectrum,without the need for cumbersome wavelength scanning processes or reliance on complex high-repetition-rate combs,while enabling adjustable *** efficacy of the proposed method is validated through simulations and *** employed a chip-scaled soliton microcomb(SMC)to compute the dispersion curves of a 14 m single-mode fiber(SMF)and a 0.05 m *** to a laser interferometer or the theoretical value given by manufacturers,the average relative error of refractive index measurement for single-mode fiber(SMF)reaches 2.8×10^(-6) and for glass reaches 3.8×10^(-6).The approach ensures high precision,while maintaining a simple system structure,with realizing adjustable resolution,thereby propelling the practical implementation of precise measurement and control-dispersion.

关键词： interferometer dispersion iteration

Photonics-assisted joint radar jamming and secure communication in the millimeter-wave band based on CE-LFM-OFDM

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Chinese optics Letters 2024年第6期22卷 205-211页

作者： Dongju Du Yanyi Wang Yingxiong Song Nan Ye Zhengxuan Li Qianwu Zhang Junjie Zhang Jian Chen Bingyao Cao Jianjun Yu key laboratory of Specialty Fiber optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced CommunicationShanghai UniversityShanghai 200444China key laboratory for Information Science of Electromagnetic Waves(MoE) Fudan UniversityShanghai 200433China

This paper reports a photonics-assisted millimeter-wave (mm-wave) joint radar jamming and secure communication system constructed through a photonic upconversion technique. In the experiments, a 30 GHz constant envelope linear frequency-modulated orthogonal frequency division modulation(CE-LFM-OFDM) signal with an instantaneous bandwidth of 1 GHz is synthesized by encoding 1 GBaud encrypted 16-quadrature amplitude modulation(16-QAM) OFDM signal. The velocity deception jamming is achieved with a spurious suppression ratio over 30 dB. Furthermore, we efficiently execute range deception jamming with a time shift of 10 ns. Simultaneously, the encrypted 16-QAM OFDM signal is successfully transmitted over a 1.2 m wireless link, with a data rate of 4 Gbit/s.

关键词： millimeter-wave radar jamming secure wireless communication

High-performance broadband photodetector based on PtSe2/MoS2 heterojunction from visible to near-infrared region

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Science China(Information Sciences) 2024年第3期67卷 263-270页

作者： Bin WANG Jian YUAN Mengqi CHE Mingxiu LIU Yuting ZOU Junru AN Fan TAN Yaru SHI Nan ZHANG Liujian QI Shaojuan LI State key laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences State key laboratory of Applied optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of Sciences School of Physics and Electronic Information Huaibei Normal University

Broadband photodetectors based on narrow bandgap 2D materials have garnered considerable interest for application in the field of optoelectronic devices. However, their large dark current hinders device performance. In this work, a PtSe2/MoS2heterojunction was fabricated for a broadband photodetector operating within the range of visible to near-infrared. The device exhibited suppressed dark currents with a high rectification ratio of 104. The built-in electric field of the heterojunction promoted carrier separation effectively, and the device achieved excellent photoelectric performance with responsivities of 1.7 × 103,27.52, and 21 mA/W at 635, 785, and 1550 nm wavelengths, respectively. Moreover, the specific detectivities(D*) were 2.2 × 1013Jones(635 nm), 3.55 × 1011Jones(785 nm), and 2.72 × 108Jones(1550 nm). The device demonstrated a rise/fall time of 131/241 μs under 1550 nm laser illumination. Visible and near-infrared imaging detection was also demonstrated based on the heterojunction device at room temperature. This work sheds light on the remarkable potential of PtSe2/MoS2heterojunctions in the domain of high-performance broadband photodetectors.

关键词： photodetector PtSe$_{2}$/MoS$_{2}$ heterojunction visible to near infrared high performance

Distribution of polarization squeezed light through a 20 km fiber channel

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Science China(Information Sciences) 2024年第5期67卷 343-344页

作者： Chao LI Siyu REN Yanru YAN Yalin LI Meihong WANG Xiaolong SU State key laboratory of Quantum optics and Quantum optics Devices Institute of Opto-Electronics Shanxi University Collaborative Innovation Center of Extreme optics Shanxi University

Polarization squeezed light plays a key role in quantum memory by transferring quantum information between atoms and photons [1], and has potential applications in quantum precision measurement [2]. For polarization squeezed light, the quantum variance of at least one Stokes operator is smaller than that of the coherent *** with the quadrature squeezed state, polarization squeezed light has the following advantages: one is that it is a bright beam, and the other is that it can be measured directly without using a local oscillator.

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Comparison of the Minimum Bounding Rectangle and Minimum Circumscribed Ellipse of Rain Cells from TRMM

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Advances in atmospheric Sciences 2024年第3期41卷 391-406页

作者： Hongke CAI Yaqin MAO Xuanhao ZHU Yunfei FU Renjun ZHOU Plateau atmospheric and Environment laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Center for atmospheric optics Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China

Based on the TRMM dataset, this paper compares the applicability of the improved MCE(minimum circumscribed ellipse), MBR(minimum bounding rectangle), and DIA(direct indexing area) methods for rain cell fitting. These three methods can reflect the geometric characteristics of clouds and apply geometric parameters to estimate the real dimensions of rain cells. The MCE method shows a major advantage in identifying the circumference of rain cells. The circumference of rain cells identified by MCE in most samples is smaller than that identified by DIA and MBR, and more similar to the observed rain cells. The area of rain cells identified by MBR is relatively robust. For rain cells composed of many pixels(N> 20), the overall performance is better than that of MCE, but the contribution of MBR to the best identification results,which have the shortest circumference and the smallest area, is less than that of MCE. The DIA method is best suited to small rain cells with a circumference of less than 100 km and an area of less than 120 km^(2), but the overall performance is mediocre. The MCE method tends to achieve the highest success at any angle, whereas there are fewer “best identification”results from DIA or MBR and more of the worst ones in the along-track direction and cross-track direction. Through this comprehensive comparison, we conclude that MCE can obtain the best fitting results with the shortest circumference and the smallest area on behalf of the high filling effect for all sizes of rain cells.

关键词： TRMM minimum bounding rectangle minimum circumscribed ellipse

A simple fabrication method of germanium-based metasurfaces

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Chinese optics Letters 2024年第7期22卷 117-120页

作者： Dongzhi Shan Jinsong Gao Nianxi Xu Naitao Song Hongda Wei Qiang Li Yi Zhao Hai Liu Qiao Sun Xiaonan Jiang Chao Li Zhiyu Zhang key laboratory of Optical System Advanced Manufacturing Technology Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China State key laboratory of Applied optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Jilin Provincial key laboratory of Advanced Optoelectronic Equipment and Instrument Manufacturing Technology Changchun 130033China

In this work,a simple fabrication method of germanium-based metasurfaces is proposed,where the deposited Al_(2)O_(3) layer with high selectivity is chosen as the hard mask and retained after the dry etching *** simulation and experimental characterization results verify the feasibility of the fabrication *** experimental study on the fabrication methods of germanium-based metasurfaces is very significant as the meta-atoms with a higher refractive index can achieve 0 to 2πtransmission phase variation with a smaller period under the same thickness-to-period ratio,which is consistent with the requirement of the period miniaturization in some cases.

关键词： metasurfaces period miniaturization refractive index.

Squeezing-enhanced resolution of radio-frequency signals

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Chinese optics Letters 2024年第7期22卷 100-104页

作者： Wei Li Mingjian Ju Qinghui Li Ruixin Li Wenxiu Yao Yimiao Wu Yajun Wang Long Tian Shaoping Shi Yaohui Zheng State key laboratory of Quantum optics and Quantum optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of Extreme optics Shanxi UniversityTaiyuan 030006China

We demonstrate a resolution enhancement scheme of radio-frequency signals by tailoring a phase-squeezed *** echo radio-frequency signals collected by photonic radar give rise to displacements in the phase quadrature of a probe laser and are estimated by the balanced homodyne *** contrast to the conventional coherent state,the noise variances for radio-frequency estimation with a squeezed state are reduced by approximately 6.9 *** to the Rayleigh criterion that defines the resolution limit,the minimum resolvable displacementΔa with a squeezed state is reduced to 45%compared to that with a coherent state,demonstrating the quantum *** squeezing-enhanced technique has extensive applications for multitarget recognition and tracking in contemporary photonic radar systems.

关键词： phase-squeezed state radio-frequency signal resolution.

The dry-hot feedback between soil moisture and atmosphere and the accelerated global warming

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Science China Earth Sciences 2024年第3期67卷 890-891页

作者： Tianjun ZHOU State key laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

Greenhouse gas (GHG) emissions have been increasing due to human activities since the Industrial Revolution, resulting in continuous warming of the global climate system and significant drought over a large parts of global land, both have shown a non-linear growth trend in recent decades(Berg et al., 2017;Zhou et al., 2019;IPCC, 2021).

关键词： warming moisture drought