We explore the impact of pumping beams with different transverse intensity profiles on the performance of the spinexchange relaxation-free(SERF) atomic magnetometers(AMs). We conduct experiments comparing the traditio...We explore the impact of pumping beams with different transverse intensity profiles on the performance of the spinexchange relaxation-free(SERF) atomic magnetometers(AMs). We conduct experiments comparing the traditional Gaussian optically-pumped AM with that utilizing the flat-top optically-pumped(FTOP) method. Our findings reveal that the FTOP-based approach outperforms the conventional method, exhibiting a larger response, a narrower magnetic resonance linewidth, and a superior low-frequency noise performance. Specifically, the use of FTOP method leads to a 16% enhancement in average sensitivity within 1 Hz–30 Hz frequency range. Our research emphasizes the significance of achieving transverse polarization uniformity in AMs, providing insights for future optimization efforts and sensitivity improvements in miniaturized magnetometers.展开更多
The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compar...The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat-top pass-band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.展开更多
A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top ...A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top output with a high extinction ratio. Compared to filters consisting of the conventional Panda polarization maintaining fibre, filters based on a high birefringence photonic crystal fibre loop mirror have better temperature stability. This kind of filter can be expected to be used widely in Wavelength-division-multiplexing(WDM) systems in the future.展开更多
Quantum correlation imaging plays an important role in quantum information processing.The existing quantum correlation imaging schemes mostly use the Gaussian beam as the pump source,resulting in the entangled two pho...Quantum correlation imaging plays an important role in quantum information processing.The existing quantum correlation imaging schemes mostly use the Gaussian beam as the pump source,resulting in the entangled two photons exhibiting a Gaussian distribution.In this Letter,we report the experimental demonstration of quantum correlation imaging using a flattop beam as the pump source,which can effectively solve the problem of imaging distortion.The sampling time for each point is 5 s,and the imaging similarity is 93.4%.The principle of this scheme is reliable,the device is simple,and it can achieve high-similarity quantum correlation imaging at room temperature.展开更多
A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram （CGH） displayed on a spatial light modulator ...A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram （CGH） displayed on a spatial light modulator （SLM）. The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.展开更多
We proposed a periodic mid-infrared broadband chiral structure. Its unit cell consists of four indium tin oxide(ITO) helix subunits with different radii. The simulation results show that the flat-topped broadband circ...We proposed a periodic mid-infrared broadband chiral structure. Its unit cell consists of four indium tin oxide(ITO) helix subunits with different radii. The simulation results show that the flat-topped broadband circular dichroism(CD) can be achieved in the mid-infrared band by optimizing the parameters of helix structures. The simulation results also show that compared with the metallic(Ag and Au) helix structures, the ITO helix structure proposed exhibits evidently better broadband CD and optical activity, which provides a new idea for the design of broadband polarization state control devices in the mid-infrared band.展开更多
A flat-topped etched diffraction grating (EDG) demultiplexer with a low polarization-dependent loss (PDL) is designed. A design and simulation method based on the method of moment (MoM) is proposed. A 65-channcl EDG d...A flat-topped etched diffraction grating (EDG) demultiplexer with a low polarization-dependent loss (PDL) is designed. A design and simulation method based on the method of moment (MoM) is proposed. A 65-channcl EDG demultiplexer with channel spacing of 100 GHz is considered as a design example. A tapered multi-mode interferometer (MMI) is used to flatten the passband of the EDG demultiplexer. The numerical results show that the exit width of the tapered waveguide impacts the loss of the TE case more than that of the TM case. Based on this fact, the exit width of the taper is optimized to obtain the lowest PDL. The tapering angle is also optimized where the minimal ripple is obtained. The designed EDG demultiplexer has an excellent flat-topped spectral response and a very low PDL.展开更多
Wide-field second-harmonic generation (SHG) was used to obtain the second-harmonic signal from the entire image area for rapid imaging, despite the fact that conventional Gaussian beam illumination has low energy util...Wide-field second-harmonic generation (SHG) was used to obtain the second-harmonic signal from the entire image area for rapid imaging, despite the fact that conventional Gaussian beam illumination has low energy utilization efficiency,which makes it easy to overexpose the intensity of the image center area. However, flat-top beam illumination has uniform spatial distribution, thereby improving the photon excitation efficiency in the entire image region and reducing laser damage and thermal effect. By combining flat-top beam illumination and wide-field SHG polarization measurement, we can calculate more myosin fibril symmetrical axis orientations through polarization analysis of 16 images at a fast imaging speed while expanding the field of view. More importantly, the application of a flat-top beam can further improve the capability of polarization measurement in SHG microscopy.展开更多
Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challe...Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challenges for spectroscopic measurements which rely on time integration of signals to improve spectral qualities.In this work,we report high-sensitivity spectroscopic measurements under pulsed high magnetic fields employing the long flat-top pulsed magnetic field technique.By means of a multiple-capacitor power supply,we were able to generate pulsed high magnetic fields with controllable flat-top pulse width and field stabilities.By synchronizing spectroscopic measurements with the waveform of the flattop magnetic field,the integration time of each spectrum can be increased by up to 100 times compared with that of the conventional spectroscopic measurements under pulsed magnetic fields,thus enabling high-sensitivity spectroscopic measurements under ultra-strong pulsed magnetic fields.These findings promise an efficient way to significantly improve the performance and extend the application of optical measurements under pulsed high magnetic fields.展开更多
In this paper,a method for designing supermassive sparse phased arrays(SMSPAs)known as the unitary modified matrix enhancement and matrix pencil(UMMEMP)method is proposed.In this method,an eigenvalue pairing method,wh...In this paper,a method for designing supermassive sparse phased arrays(SMSPAs)known as the unitary modified matrix enhancement and matrix pencil(UMMEMP)method is proposed.In this method,an eigenvalue pairing method,which is inspired by the modified MEMP,effectively pairs the repeated eigenvalues intractable in the unitary matrix pencil method,and it is more effective in determining the locations of elements in the sparse array.Three numerical examples and a full-wave validation are presented to demonstrate the effectiveness of the method,implemented via SMSPA,in achieving low sidelobe level wide-angle scanning radiation patterns,circular flattop radiation patterns,and ultra wide-angle scanning radiation patterns.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 62303029)the China Postdoctoral Science Foundation (Grant No. 2022M720364)the Innovation Program for Quantum Science and Technology (Grant Nos. 2021ZD0300500 and 2021ZD0300503)。
文摘We explore the impact of pumping beams with different transverse intensity profiles on the performance of the spinexchange relaxation-free(SERF) atomic magnetometers(AMs). We conduct experiments comparing the traditional Gaussian optically-pumped AM with that utilizing the flat-top optically-pumped(FTOP) method. Our findings reveal that the FTOP-based approach outperforms the conventional method, exhibiting a larger response, a narrower magnetic resonance linewidth, and a superior low-frequency noise performance. Specifically, the use of FTOP method leads to a 16% enhancement in average sensitivity within 1 Hz–30 Hz frequency range. Our research emphasizes the significance of achieving transverse polarization uniformity in AMs, providing insights for future optimization efforts and sensitivity improvements in miniaturized magnetometers.
文摘The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat-top pass-band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.
基金supported by the"100 Projects"of Creative Research for the Undergraduates of Nankai University under Grant(BX6-224)
文摘A novel all-fibre flat-top comb filter based on a high birefringence photonic crystal fibre loop mirror is proposed and demonstrated. We simulate theoretically its output spectra and experimentally realize a flat-top output with a high extinction ratio. Compared to filters consisting of the conventional Panda polarization maintaining fibre, filters based on a high birefringence photonic crystal fibre loop mirror have better temperature stability. This kind of filter can be expected to be used widely in Wavelength-division-multiplexing(WDM) systems in the future.
基金supported by the National Natural Science Foundation of China(Nos.12104506,62205372,and62201597)the Scientific Research Project of National University of Defense Technology(Nos.22-ZZCX-07,23-ZZCX-JDZ-46,24-ZZCX-JDZ-43,and ZK22-35)+2 种基金the Youth Independent Innovation Science Foundation Project of National University of Defense Technology(No.ZK23-45)the Hefei Comprehensive National Science Center Project(No.KY23C502)the Director Fund Project of Advanced Laser Technology Laboratory Foundation of Anhui Province(No.KY22C608)。
文摘Quantum correlation imaging plays an important role in quantum information processing.The existing quantum correlation imaging schemes mostly use the Gaussian beam as the pump source,resulting in the entangled two photons exhibiting a Gaussian distribution.In this Letter,we report the experimental demonstration of quantum correlation imaging using a flattop beam as the pump source,which can effectively solve the problem of imaging distortion.The sampling time for each point is 5 s,and the imaging similarity is 93.4%.The principle of this scheme is reliable,the device is simple,and it can achieve high-similarity quantum correlation imaging at room temperature.
基金supported by the National Natural Science Foundation of China (No.11074105)the Natural Science Foundation of Shandong Province (No.Z2008A02)the Ludong University Natural Science Doctorate Program (No.LY20082802)
文摘A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram （CGH） displayed on a spatial light modulator （SLM）. The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.
基金This work was supported by the National Natural Science Foundation of China(Nos.61771227 and 62071208)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘We proposed a periodic mid-infrared broadband chiral structure. Its unit cell consists of four indium tin oxide(ITO) helix subunits with different radii. The simulation results show that the flat-topped broadband circular dichroism(CD) can be achieved in the mid-infrared band by optimizing the parameters of helix structures. The simulation results also show that compared with the metallic(Ag and Au) helix structures, the ITO helix structure proposed exhibits evidently better broadband CD and optical activity, which provides a new idea for the design of broadband polarization state control devices in the mid-infrared band.
基金This work was supported by the National Nat- ural Science Foundation of China under Grant No. 90101024 and 60377022.
文摘A flat-topped etched diffraction grating (EDG) demultiplexer with a low polarization-dependent loss (PDL) is designed. A design and simulation method based on the method of moment (MoM) is proposed. A 65-channcl EDG demultiplexer with channel spacing of 100 GHz is considered as a design example. A tapered multi-mode interferometer (MMI) is used to flatten the passband of the EDG demultiplexer. The numerical results show that the exit width of the tapered waveguide impacts the loss of the TE case more than that of the TM case. Based on this fact, the exit width of the taper is optimized to obtain the lowest PDL. The tapering angle is also optimized where the minimal ripple is obtained. The designed EDG demultiplexer has an excellent flat-topped spectral response and a very low PDL.
基金supported by the National Key Research and Development Program of China (No.2021YFF0502900)National Natural Science Foundation of China (Nos.62225505,61935012,62175163,61835009,62127819,and 62205220)+1 种基金Shenzhen Key Projects (No.JCYJ20200109105404067),Shenzhen Talent Innovation Project (No.RCJC2021070 6091949022)Shenzhen Science and Technology Planning Project (No.ZDSYS20210623092006020)。
文摘Wide-field second-harmonic generation (SHG) was used to obtain the second-harmonic signal from the entire image area for rapid imaging, despite the fact that conventional Gaussian beam illumination has low energy utilization efficiency,which makes it easy to overexpose the intensity of the image center area. However, flat-top beam illumination has uniform spatial distribution, thereby improving the photon excitation efficiency in the entire image region and reducing laser damage and thermal effect. By combining flat-top beam illumination and wide-field SHG polarization measurement, we can calculate more myosin fibril symmetrical axis orientations through polarization analysis of 16 images at a fast imaging speed while expanding the field of view. More importantly, the application of a flat-top beam can further improve the capability of polarization measurement in SHG microscopy.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFA1602700)the National Natural Science Foundation of China(Grant No.12274159)。
文摘Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challenges for spectroscopic measurements which rely on time integration of signals to improve spectral qualities.In this work,we report high-sensitivity spectroscopic measurements under pulsed high magnetic fields employing the long flat-top pulsed magnetic field technique.By means of a multiple-capacitor power supply,we were able to generate pulsed high magnetic fields with controllable flat-top pulse width and field stabilities.By synchronizing spectroscopic measurements with the waveform of the flattop magnetic field,the integration time of each spectrum can be increased by up to 100 times compared with that of the conventional spectroscopic measurements under pulsed magnetic fields,thus enabling high-sensitivity spectroscopic measurements under ultra-strong pulsed magnetic fields.These findings promise an efficient way to significantly improve the performance and extend the application of optical measurements under pulsed high magnetic fields.
文摘In this paper,a method for designing supermassive sparse phased arrays(SMSPAs)known as the unitary modified matrix enhancement and matrix pencil(UMMEMP)method is proposed.In this method,an eigenvalue pairing method,which is inspired by the modified MEMP,effectively pairs the repeated eigenvalues intractable in the unitary matrix pencil method,and it is more effective in determining the locations of elements in the sparse array.Three numerical examples and a full-wave validation are presented to demonstrate the effectiveness of the method,implemented via SMSPA,in achieving low sidelobe level wide-angle scanning radiation patterns,circular flattop radiation patterns,and ultra wide-angle scanning radiation patterns.
