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Microwave electrometry with Rydberg atoms in a vapor cell using microwave amplitude modulation

Chinese Physics B 2024年第5期33卷 65-74页

作者：郝建海贾凤东崔越王昱寒周飞刘修彬张剑谢锋白金海尤建琦王宇钟志萍 School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China Science and Technology on Metrology and Calibration Laboratory Changcheng Institute of Metrology & MeasurementAviation Industry Corporation of ChinaBeijing 100095China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the microwave(MW)electric *** addition to the two zero-crossing points interval△f_(zeros),the dispersion signal has two positive maxima with an interval defined as the shoulder interval△f_(sho),which is theoretically expected to be used to measure a much weaker MW electric *** relationship of the MW field strength E_(MW)and△f_(sho)is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz *** results show that△f_(sho)can be used to characterize the much weaker E_(MW)than that of△f_(zeros)and the traditional EIT–AT splitting interval△f_(m);the minimum E_(MW)measured by△f_(sho)is about 30 times smaller than that by△f_(m).As an example,the minimum E_(MW)at 9.2 GHz that can be characterized by△f_(sho)is 0.056 mV/cm,which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary *** proposed method can improve the weak limit and sensitivity of E_(MW)measured by the spectral frequency interval,which is important in the direct measurement of weak E_(MW).

关键词： quantum sensor Rydberg atoms electromagnetically induced transparency amplitude modulation

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amplitude modulation excitation for cancellous bone evaluation using a portable ultrasonic backscatter instrumentation

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Chinese Physics B 2022年第11期31卷 106-114页

作者： Boyi Li Chengcheng Liu Xin Liu Tho N.H.T.Tran Ying Li Dan Li Dongsheng Bi Duwei Liu Dean Ta Academy for Engineering and Technology Fudan UniversityShanghai 200433China The Center for Biomedical Engineering Fudan UniversityShanghai 200433China The State Key Laboratory of Medical Neurobiology Fudan UniversityShanghai 200433China

The ultrasonic backscatter(UB)has the advantage of non-invasively obtaining bone density and structure,expected to be an assessment tool for early diagnosis *** former UB measurements were based on exciting a short single-pulse and analyzing the ultrasonic signals backscattered in *** study aims to examine amplitude modulation(AM)ultrasonic excitation with UB measurements for predicting bone *** AM multiple lengths excitation and backscatter measurement(AM-UB)functions were integrated into a portable ultrasonic instrument for bone *** apparent integrated backscatter coefficient in the AM excitation(AIB_(AM))was evaluated on the AM-UB *** correlation coefficients of the AIB_(AM) estimating volume fraction(BV/TV),structure model index(SMI),and bone mineral density(BMD)were then *** correlations(|R|=0.82-0.93,p<0.05)were observed between the AIB_(AM),BV/TV,SMI,and *** growing the AM excitation length,the AIB_(AM) values exhibit more stability both in 1.0-MHz and 3.5-MHz *** recommendations in AM-UB measurement were that the avoided length(T1)should be lower than AM excitation length,and the analysis length(T2)should be enough long but not more than AM excitation *** authors conducted an AM-UB measurement for cancellous bone *** the AM excitation length could substantially enhance AIB_(AM) values stability with varying analyzed *** study suggests the portable AM-UB instrument with the integration of real-time analytics software that might provide a potential tool for osteoporosis early screening.

关键词： ultrasonic backscatter measurement amplitude modulation osteoporosis bone diagnosis

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amplitude modulation and extreme events in turbulent channel flow

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Acta Mechanica Sinica 2018年第1期34卷 1-9页

作者： Y.C.Yao W.X.Huang C.X.Xu AML Department of Engineering Mechanics Tsinghua University

amplitude modulation of near-wall turbulence by large-scale structures in the outer layer is investigated by direct numerical simulation of turbulent channel flows at Reynolds number Re= 540, 1000, 2000. The effect of modulation is obvious in the two-point cross-section correlation map, and the correlation coefficients increase significantly with the Reynolds number. The influence of modulation is reflected in the tail of the probability density function of the near-wall flow signals, which expands as the Reynolds number increases. The flatness factor provides a quantitative description of the high fluctuation events due to modulation. Vortical structures associated with modulation are revealed by conditionally averaging the flow field of the near-wall extreme events, providing a depiction of how the influence of the large-scale structures penetrate towards the near-wall region.

关键词： Wall turbulence amplitude modulation Flatness Extreme events

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An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer

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Chinese Physics B 2022年第9期31卷 254-259页

作者： Xiu-Bin Liu Feng-Dong Jia Huai-Yu Zhang Jiong Mei Wei-Chen Liang Fei Zhou Yong-Hong Yu Ya Liu Jian Zhang Feng Xie Zhi-Ping Zhong School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Institute of Physics Chinese Academy of SciencesBeijing 100190China National Time Service Centre Chinese Academy of SciencesXi'an 710600ChinaUniversity of Chinese Academy of SciencesBeijing 100049China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)*** phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)*** this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat *** the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF *** amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF *** minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical *** study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.

关键词： quantum sensor phase detector Rydberg atoms micorwave electromagnetically induced transparency amplitude modulation

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amplitude modulation measurement of symmetrical microwave power sensor

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Journal of Southeast University(English Edition) 2010年第1期26卷 68-72页

作者：王德波廖小平田涛东南大学MEMS教育部重点实验室南京210096

In order to reduce the mismatch error, a direct current （DC） calibration method is introduced when the modulated microwave signal is measured. The microwave power is input to the left section of the power sensor, and the DC power is input to the right of the power sensor. Due to the existence of parasitic loss and electromagnetic coupling, the microwave power results in a mismatch error. However, the DC power does not have the mismatch error. So the DC power applied in the right section can calibrate the mismatch error of the microwave power in the left section. The calibration factor is measured at different modulation rates and modulation *** measurement results show that the carrier frequency is the major factor influencing the measurement results. After calibration, the carrier frequency and the modulation rate have little effect on the output voltage. The frequency response becomes relatively flat in the frequency range up to 20 GHz, and the sensitivity on average is enhanced by about 0.12 mV/dBm. Therefore, the DC calibration method has a certain reference value for the terminal-type microwave power sensor.

关键词： amplitude modulation symmetrical power sensor direct current (DC) calibration

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Simultaneous optical signal to noise ratio and symbol rate estimation with blind chromatic dispersion compensation for auxiliary amplitude modulation optical signals

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Chinese Optics Letters 2016年第9期14卷 15-19页

作者：魏俊宇覃江毅黄芝平郭晓俊 College of Mechatronics Engineering and Automation National University of Defense Technology

Based on the peak to valley ratio（PTVR） of the average magnitude difference function（AMDF）, we present a novel optical signal to noise ratio（OSNR） and symbol rate（SR） estimation method for commonly used auxiliary amplitude modulations（AAMs）. Moreover, it is demonstrated that the influence of chromatic dispersion（CD）on the method can be mitigated by maximizing the PTVR of the AMDF with additional tunable dispersion compensators. The results of simulations show that the OSNR estimation error can be kept within 0.8 dB in the wide OSNR range of（12, 32） dB, while the SR estimation error is below 0.079% for four widely used10 Gsymbol/s AAM signals.

关键词： amplitude modulation Blind equalization Chromatic dispersion Estimation modulation Signal to noise ratio

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Wideband Rydberg atom-based receiver for amplitude modulation radio frequency communication

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Chinese Optics Letters 2022年第8期20卷 24-28页

作者： Kai Yang Zhanshan Sun Ruiqi Mao Yi Lin Yi Liu Qiang An Yunqi Fu College of Electronic Science and Technology National University of Defense TechnologyChangsha 410073China

Based on Autler–Townes splitting and AC Stark shifts,we present a Rydberg atom-based receiver for determining the amplitude modulation(AM)frequency among a wideband carrier range utilizing a cesium atomic vapor *** verify this approach,we measured the signal-to-noise ratio and the data capacity with a 10 kHz AM frequency in the carrier range from 2 GHz to 18 *** changing the lasers,the working band can be easily extended to a higher range by optimizing the feed antenna and experimental configurations.

关键词： Rydberg atoms wideband atomic receiver amplitude modulation

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Pilot-added carrier-phase recovery scheme for Nyquist M-ary quadrature amplitude modulation optical fiber communication system

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Chinese Optics Letters 2016年第2期14卷 6-10页

作者：张文博潘董威宿晓飞张晓光席丽霞唐先锋 School of Science Beijing University of Posts and Telecommunications State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

A new two-stage carrier-phase recovery scheme using a combination of an optical pilot-aided algorithm with the crossed constellation transformation algorithm for either square-framed or non-square-framed M-level- quadrature amplitude modulation （QAM） Nyquist systems is proposed. It is verified in 32- and 128-QAM systems that it can provide high linewidth tolerance with little complexity.

关键词： Algorithms amplitude modulation modulation Optical communication Optical fibers Quadrature amplitude modulation

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Research on the design of metalens with achromatic and amplitude modulation

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Optoelectronics Letters 2023年第2期19卷 77-82页

作者： XU Yuanyuan GENG Yan LIANG Yu TANG Furui SUN Yujuan WANG Yawei School of Physics and Electrical Engineering Jiangsu UniversityZhenjiang 212013China

Metalenses are two-dimensional planar metamaterial lenses, which have the advantages of high efficiency and easy integration. However, most metalenses cannot modulate the light intensity, which limits their applications. To deal with it, taking advantage of flexible regulation of the beam amplitude and phase by the metalens, the geometric phase method is selected to design the dual-function metalens. It can effectively eliminate chromatic aberration in a visible light band from 535 nm to 600 nm and achieve amplitude modulation. After transmitting the metalens, the amplitudes of the beam respectively turn into 0.2 and 0.9. In this way, the amount of transmission of metalens in the preset band can be quantitatively controlled. According to the distribution characteristics of light diffraction intensity, the metalens designed can play a dual modulation role of achromatism and interference double-beam equilibrium in the paper, to meet the needs of miniaturization and integration of the optical system. The achromatic and amplitude-modulated metalens will have great application potential in optical holographic imaging and super-resolution focusing.

关键词： achromatic amplitude modulation

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Polarization and amplitude hybrid modulation of longitudinally polarized subwavelength-sized optical needle

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Chinese Optics Letters 2013年第5期11卷 61-64页

作者：郭丽娇闵长俊魏仕彪袁小聪 Institute of Modern Optics Key Laboratory of Optical Information Science and Technology Ministry of Education of China Nankai University

We present a method of both polarization and amplitude modulations on an incident beam to obtain a longitudinally polarized subwavelength-sized optical needle. A 4-f system with a spatial light modulator is used to generate experimentally a two-mode alternate cylindrical vector beam by polarization modulation, enhancing performance and facilitating implementation. We optimize the beam focusing properties after passing the beam through an annular aperture to obtain amplitude modulation by the simulated annealing algorithm. Numerical results indicate that a sharp focal spot （0.417A） with a long focal depth （8A） and a strong longitudinally polarized field can be easily achieved.

关键词： amplitude modulation Diffractive optics Light modulators Needles

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