The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed a...The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed and then relationships between the space and frequency point, at which the signals can be extracted, are given. When expected signals are band- limit, the conditions of the selected sensor space, which should be satisfied, are given. Lastly, Performance of interference suppression is analyzed when the amplitude of interference power spectra of signals Received by three sensors fluctuates, and the expressions of relative error of the extracted signals and processing gain are derived. The theoretical and simulation results show that signals can be extracted from strong background interference without any information about signals and interference expect for the arriving direction of signals, that the space between sensors should be smaller than half wavelength of upper limit freqency when the expected signals are band-limit, and that performance of extracting signals will decline with the increase of fluctuation of interference spectrum amplitude.展开更多
Comparing with traditional underwater acoustic system which only utilizes pressure information, combine sensor system processes pressure together with particle velocity information of sound field. More information ce...Comparing with traditional underwater acoustic system which only utilizes pressure information, combine sensor system processes pressure together with particle velocity information of sound field. More information certainly brings nicer processing result. By using spatial directional information collected by combine sensor, the Coherent Interference Energy Suppress (CIES) technology, which can effectively suppress coherent interference and detect linear spectrum signal and wide-band continuous-spectrum signal as well, is presented. Current research has shown favorite result, and further research is going on.展开更多
Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the l...Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.展开更多
The optical Vernier effect has garnered significant research attention and found widespread applications in enhancing the measurement sensitivity of optical fiber interferometric sensors.Typically,Vernier sensor inter...The optical Vernier effect has garnered significant research attention and found widespread applications in enhancing the measurement sensitivity of optical fiber interferometric sensors.Typically,Vernier sensor interrogation involves measuring its optical spectrum across a wide wavelength range using a high-precision spectrometer.This process is further complicated by the intricate signal processing required for accurately extracting the Vernier envelope,which can inadvertently introduce errors that compromise sensing performance.In this work,we introduce a novel approach to interrogating Vernier sensors based on a coherent microwave interferenceassisted measurement technique.Instead of measuring the optical spectrum,we acquire the frequency response of the Vernier optical fiber sensor using a vector network analyzer.This response includes a characteristic notch that is highly sensitive to external perturbations.We discuss in detail the underlying physics of coherent microwave interference-based notch generation and the sensing principle.As a proof of concept,we construct a Vernier sensor using two air-gap Fabry–Perot interferometers arranged in parallel,demonstrating high-sensitivity strain sensing through microwave-domain measurements.The introduced technique is straightforward to implement,and the characteristic sensing signal is easy to demodulate and highly sensitive,presenting an excellent solution to the complexities of existing optical Vernier sensor systems.展开更多
Interferences in the quantum fluctuations of the output fields are demonstrated in four-wave mixing processes inside a cavity, which is driven by two quantized fields at the signal and the idler frequencies. These int...Interferences in the quantum fluctuations of the output fields are demonstrated in four-wave mixing processes inside a cavity, which is driven by two quantized fields at the signal and the idler frequencies. These interferences depend on the phase fluctuations of the input fields and induce mode splitting in the transmission spectra.展开更多
We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for ...We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.展开更多
Multiplexing multiple yet distinct functionalities in one single device is highly desired for modern integration optics,but conventional devices are usually of bulky sizes and/or low efficiencies.While recently propos...Multiplexing multiple yet distinct functionalities in one single device is highly desired for modern integration optics,but conventional devices are usually of bulky sizes and/or low efficiencies.While recently proposed metasurfaces can be ultrathin and highly efficient,functionalities multiplexed by metadevices so far are typically restricted to two,dictated by the number of independent polarization states of the incident light.Here,we propose a generic approach to design metadevices exhibiting wave-control functionalities far exceeding two,based on coherent wave interferences continuously tuned by varying the incident polarization.After designing a series of building-block metaatoms with optical properties experimentally characterized,we construct two metadevices based on the proposed strategy and experimentally demonstrate their polarization-tuned multifunctionalities at the wavelength of 1550 nm.Specifically,upon continuously modulating the incident polarization along different paths on the Poincare’s sphere,we show that the first device can generate two spatially non-overlapping vortex beams with strengths continuously tuned,while the second device can generate a vectorial vortex beam carrying continuously-tuned polarization distribution and/or orbital angular momentum.Our proposed strategy significantly expands the wave-control functionalities equipped with a single optical device,which may stimulate numerous applications in integration optics.展开更多
Quantum transport arises from the interplay of coherent interference,impurity scattering,and inter-particle interactions[1,2].The competition between disorder and interaction leads to a transition between localized an...Quantum transport arises from the interplay of coherent interference,impurity scattering,and inter-particle interactions[1,2].The competition between disorder and interaction leads to a transition between localized and delocalized phases,and many breakthroughs have been made[3].While traditional theories focus on electronic systems,recent advancements in quantum technologies,such as Bose-Einstein condensates[4],superconducting qubits[5],and trapped ions[6],enable direct simulations of quantum transport.These systems provide new opportunities to explore quantum transport beyond traditional theories,offering direct insights into particle distribution in space and time[7].展开更多
文摘The Principles of coherent interference suppression are presented by a three-sensor array. The formulae of extracting expected signals from strong interference are derived. The selection of sensor space is discussed and then relationships between the space and frequency point, at which the signals can be extracted, are given. When expected signals are band- limit, the conditions of the selected sensor space, which should be satisfied, are given. Lastly, Performance of interference suppression is analyzed when the amplitude of interference power spectra of signals Received by three sensors fluctuates, and the expressions of relative error of the extracted signals and processing gain are derived. The theoretical and simulation results show that signals can be extracted from strong background interference without any information about signals and interference expect for the arriving direction of signals, that the space between sensors should be smaller than half wavelength of upper limit freqency when the expected signals are band-limit, and that performance of extracting signals will decline with the increase of fluctuation of interference spectrum amplitude.
基金This work is supported by the National Natural Science Foundation of China and Doctor Foundation ofNEC.
文摘Comparing with traditional underwater acoustic system which only utilizes pressure information, combine sensor system processes pressure together with particle velocity information of sound field. More information certainly brings nicer processing result. By using spatial directional information collected by combine sensor, the Coherent Interference Energy Suppress (CIES) technology, which can effectively suppress coherent interference and detect linear spectrum signal and wide-band continuous-spectrum signal as well, is presented. Current research has shown favorite result, and further research is going on.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301202)the National Natural Science Foundation of China(Grant Nos.11674311 and U20A20205)。
文摘Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.
文摘The optical Vernier effect has garnered significant research attention and found widespread applications in enhancing the measurement sensitivity of optical fiber interferometric sensors.Typically,Vernier sensor interrogation involves measuring its optical spectrum across a wide wavelength range using a high-precision spectrometer.This process is further complicated by the intricate signal processing required for accurately extracting the Vernier envelope,which can inadvertently introduce errors that compromise sensing performance.In this work,we introduce a novel approach to interrogating Vernier sensors based on a coherent microwave interferenceassisted measurement technique.Instead of measuring the optical spectrum,we acquire the frequency response of the Vernier optical fiber sensor using a vector network analyzer.This response includes a characteristic notch that is highly sensitive to external perturbations.We discuss in detail the underlying physics of coherent microwave interference-based notch generation and the sensing principle.As a proof of concept,we construct a Vernier sensor using two air-gap Fabry–Perot interferometers arranged in parallel,demonstrating high-sensitivity strain sensing through microwave-domain measurements.The introduced technique is straightforward to implement,and the characteristic sensing signal is easy to demodulate and highly sensitive,presenting an excellent solution to the complexities of existing optical Vernier sensor systems.
基金Project supported by the New Staff Research Support Plan of Xi’an Jiaotong University,China (Grant No. 08141015)
文摘Interferences in the quantum fluctuations of the output fields are demonstrated in four-wave mixing processes inside a cavity, which is driven by two quantized fields at the signal and the idler frequencies. These interferences depend on the phase fluctuations of the input fields and induce mode splitting in the transmission spectra.
文摘We present examples of a controlled numerical experiment that contribute towards understanding of the physical phenomena that lead to the reduction of coherency of strong earthquake ground motion.We show examples for separation distance of 100 m between the two points on the ground surface,which is in the range of engineering interest.Our examples illustrate the consequences of:(a)standing waves that result from interference of the incident and reflected waves from a near vertical contrast in material properties,(b)standing waves within a concave inhomogeneity(a semi-circular valley in our examples),and(c)smaller motions in the diffraction zone,behind the inhomogeneity.We show that it is possible to reduce coherency,to the extent observed for recorded strong earthquake ground motion,even by a single inclusion in a half space,for incident ground motion that is coherent.We also illustrate the combined effects of geometric spreading and finite fault width,superimposed on the otherwise dominating effects caused by interference.Our examples show reduction of coherence for specific angles of incident waves,while,for other angles of incidence,the coherence remains essentially equal to one.
基金National Key Research and Development Program of China(Grant No.2022YFA1404701)National Natural Science Foundation of China(Grant Nos.12221004,62192771)Natural Science Foundation of Shanghai(Grant Nos.20JC141460,23DZ2260100)。
文摘Multiplexing multiple yet distinct functionalities in one single device is highly desired for modern integration optics,but conventional devices are usually of bulky sizes and/or low efficiencies.While recently proposed metasurfaces can be ultrathin and highly efficient,functionalities multiplexed by metadevices so far are typically restricted to two,dictated by the number of independent polarization states of the incident light.Here,we propose a generic approach to design metadevices exhibiting wave-control functionalities far exceeding two,based on coherent wave interferences continuously tuned by varying the incident polarization.After designing a series of building-block metaatoms with optical properties experimentally characterized,we construct two metadevices based on the proposed strategy and experimentally demonstrate their polarization-tuned multifunctionalities at the wavelength of 1550 nm.Specifically,upon continuously modulating the incident polarization along different paths on the Poincare’s sphere,we show that the first device can generate two spatially non-overlapping vortex beams with strengths continuously tuned,while the second device can generate a vectorial vortex beam carrying continuously-tuned polarization distribution and/or orbital angular momentum.Our proposed strategy significantly expands the wave-control functionalities equipped with a single optical device,which may stimulate numerous applications in integration optics.
基金supported by the Excellent Young Scientists Fund Program(Overseas)of Chinathe National Natural Science Foundation of China(12274034,12020101003,92250301,and 12250710126)+1 种基金the China Postdoctoral Science Foundation(Y24PJ2425214)the strong support from the State Key Laboratory of Low-Dimensional Quantum Physics at Tsinghua University。
文摘Quantum transport arises from the interplay of coherent interference,impurity scattering,and inter-particle interactions[1,2].The competition between disorder and interaction leads to a transition between localized and delocalized phases,and many breakthroughs have been made[3].While traditional theories focus on electronic systems,recent advancements in quantum technologies,such as Bose-Einstein condensates[4],superconducting qubits[5],and trapped ions[6],enable direct simulations of quantum transport.These systems provide new opportunities to explore quantum transport beyond traditional theories,offering direct insights into particle distribution in space and time[7].
