An optical phased array(OPA)is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems.The performance of the OPA largely depends on the phase shifter,which afects pow...An optical phased array(OPA)is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems.The performance of the OPA largely depends on the phase shifter,which afects power consumption,insertion loss,modulation speed,and footprint.However,for a thermo-optic phase shifter,achieving good performance in all aspects is challenging due to trade-ofs among these aspects.In this work,we propose and demonstrate two types of energy-efcient optical phase shifters that overcome these trade-ofs and achieve a well-balanced performance in all aspects.Additionally,the proposed round-spiral phase shifter is robust in fabrication and fully compatible with deep ultraviolet(DUV)processes,making it an ideal building block for large-scale photonic integrated circuits(PICs).Using the high-performance phase shifter,we propose a periodic OPA with low power consumption,whose maximum electric power consumption within the feld of view is only 0.33 W.Moreover,we designed Gaussian power distribution in both the azimuthal(ψ)and polar(θ)directions and experimentally achieved a large sidelobe suppression ratio of 15.1 and 25 dB,respectively.展开更多
This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquidcrystal-based phased array(LCPA),including the design,over-the-air(OTA)in-array calibration,and experimental vali...This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquidcrystal-based phased array(LCPA),including the design,over-the-air(OTA)in-array calibration,and experimental validation.The LCPA contains 16 phase-shifting radiating channels,each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter(LCPS)based on a loaded differential line structure.Thanks to its slow-wave properties,the LCPS exhibits a maximum phase-shifting range of more than 360°with a figure of merit of 78.3(°)·dB^(-1)based on a liquid crystal layer with a thickness of only 5μm.Furthermore,an automatic OTA calibration based on a state ergodic method is proposed,which enables the extraction of the phase-voltage curve of every individual LCPA channel.The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm,experimentally demonstrating a scanned circularly polarized beam from-40°to+40°with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB.The bandwidth of the LCPA,which satisfies the require-ments of port reflection(|S_(11)|)<-15 dB,an axial ratio(AR)<3 dB,beam squinting<3°,and a gain variation<2.2 dB,spans from 25.5 to 26.0 GHz.The total efficiency is about 34%,which represents a new state of the art.The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams,along with the systematic design and calibration methodology,holds potential promise for a variety of millimeter-wave applications.展开更多
This paper considers a high energy efficiency dynamic connected(HEDC)structure,which promotes the practicability and reduces the power consumption of hybrid precoding system by lowresolution phase shifters(PSs).Based ...This paper considers a high energy efficiency dynamic connected(HEDC)structure,which promotes the practicability and reduces the power consumption of hybrid precoding system by lowresolution phase shifters(PSs).Based on the proposed structure,a new hybrid precoding algorithm is presented to optimize the energy efficiency,namely,HP-HEDC algorithm.Firstly,via a new defined effective optimal precoding matrix,the problem of optimizing the analog switch precoding matrix is formulated as a sparse representation problem.Thus,the optimal analog switch precoding matrix can be readily obtained by the branch-and-bound method.Then,the digital precoding matrix optimization problem is modeled as a dictionary update problem and solved by the method of optimal direction(MOD).Finally,the diagonal entries of the analog PS precoding matrix are optimized by exhaustive search independently since PS and antenna is one-to-one.Simulation results show that the HEDC structure enjoys low power consumption and satisfactory spectral efficiency.The proposed algorithm presents at least 50%energy efficiency improvement compared with other algorithms when the PS resolution is set as 3-bit.展开更多
Barium strontium titanate/magnesia （BSTO/MgO） ferroeleetric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5 % on dielectr...Barium strontium titanate/magnesia （BSTO/MgO） ferroeleetric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5 % on dielectric behaviors of BSTO/MgO composites were studied in terms of permittivity, loss tangent and tunability both at low and high frequencies. The dielectric constant of Y2O3 and Er2O3 doped samples decreases from 160 to 120, and the microwave loss of La2O3 and Er2O3 doped samples decreases from 8.2 x 10-3 to 6.8 x 10-3. Only La203 increases the tunability of BSTO/MgO system, from 13.6% to 14.8%. For the La2O3 doped sample, the value of tunability is more than 14% with the external DC field 4000 V·mm^-1 and the microwave loss at 2.47 GHz is 6.77 ×10^-3 and, hence, it can basically meet the requirements of phase shifters working at microwave frequencies. The influence mechanism was discussed preliminarily.展开更多
Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one ...Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one of the basic tuning devices,the thermo-optic phase shifter(TOPS)plays an important role in all these applications.A TOPS with the merits of easy fabrication,low power consumption,small thermal time constant,low insertion loss,small footprint,and low crosstalk,is needed to improve the performance and lower the cost of the above applications.To meet these demands,various TOPS have been proposed and experimentally demonstrated on different foundry platforms In this paper,we review the state-of-the-art of TOPS,including metal heater,doped silicon,silicide,with silicon substrate undercut for heat insulation,folded waveguide structure,and multi-pass waveguide structure.We further compare these TOPSs and propose the directions of the future developments on TOPS.展开更多
As an important component of the stirling-type pulse tube cryocooler(SPTC),an efficient phase shifter can significantly improve the cooling capacity.Compared to the common phase shifter,the active warm displacer(AWD)h...As an important component of the stirling-type pulse tube cryocooler(SPTC),an efficient phase shifter can significantly improve the cooling capacity.Compared to the common phase shifter,the active warm displacer(AWD)has a wider phase adjustment range and therefore can obtain a better phase relationship easily.Based on a two-stage thermal-coupled SPTC operating in the 20 K range,this paper studied the influence of the swept volume ratio between the compressor and displacer.The research found that the swept volume ratio changes the cooling capacity and efficiency of the cryocooler mainly by changing the phase difference between the pressure wave and the volume flow at the cold end.It was found from the results of the simulation and experiments that there is an optimal displacement of the displacer(Xd)of 2.5 mm and an optimal phase angle of 15°to obtain the highest cooling efficiency while the displacement of the compressor is constant.The cooling capacity at 20 K is 1.3 W while the input electrical power of the second stage compressor is 202 W,which indicates an overall relative Carnot efficiency(rCOP)of 0.055 in terms of input electrical power.In addition,due to the reasonable setting of precooling temperature and capacity,the swept volume ratio and phase at the maximum cooling capacity and maximum efficiency are consistent in this study.The research improves the understanding of phase shifters and has guiding significance for the optimization of the SPTC working below 20 K.展开更多
The China Dark Matter Experiment （CDEX） is a low background experiment at China Jinping Under- ground Laboratory （CJPL） designed to directly detect dark matter with a high-purity germanium （HPGe） detector. In th...The China Dark Matter Experiment （CDEX） is a low background experiment at China Jinping Under- ground Laboratory （CJPL） designed to directly detect dark matter with a high-purity germanium （HPGe） detector. In the second phase, CDEX-10, which has a 10 kg germanium array detector system, a liquid argon （LAr） anti- Compton active shielding and cooling system is proposed. To study the properties of the LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV γ rays at different positions. The good agreement between the experimental and simulation results has provided a reasonable understanding and determination of the important parameters such as the surviving fraction of the Ar2 excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.展开更多
This paper proposed an X-band 6-bit passive phase shifter （PS） designed in 0.18 μm silicon-on-insulator （SOI） CMOS technology, which solves the key problem of high integration degree, low power, and a small size ...This paper proposed an X-band 6-bit passive phase shifter （PS） designed in 0.18 μm silicon-on-insulator （SOI） CMOS technology, which solves the key problem of high integration degree, low power, and a small size T/R module. The switched-topology is employed to achieve broadband and fiat phase shift. The ESD circuit and driver are also integrated in the PS. It covers the frequency band from 7.5 to 10.5 GHz with an EMS phase error less than 7.5%. The input and output VSWRs are less than 2 and the insertion loss （IL） is between 8-14 dB across the 7.5 to 10.5 GHz, with a maximum IL difference of 4 dB. The input 1 dB compression point （IP1dB） is 20 dBm.展开更多
基金the Novo Nordisk Fonden(NNF22OC0080333)Villum Fonden(15401).
文摘An optical phased array(OPA)is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems.The performance of the OPA largely depends on the phase shifter,which afects power consumption,insertion loss,modulation speed,and footprint.However,for a thermo-optic phase shifter,achieving good performance in all aspects is challenging due to trade-ofs among these aspects.In this work,we propose and demonstrate two types of energy-efcient optical phase shifters that overcome these trade-ofs and achieve a well-balanced performance in all aspects.Additionally,the proposed round-spiral phase shifter is robust in fabrication and fully compatible with deep ultraviolet(DUV)processes,making it an ideal building block for large-scale photonic integrated circuits(PICs).Using the high-performance phase shifter,we propose a periodic OPA with low power consumption,whose maximum electric power consumption within the feld of view is only 0.33 W.Moreover,we designed Gaussian power distribution in both the azimuthal(ψ)and polar(θ)directions and experimentally achieved a large sidelobe suppression ratio of 15.1 and 25 dB,respectively.
基金supported in part by the National Natural Science Foundation of China(NSFC62122019 and 62293492)+2 种基金the National Key Research and Development Program of China(2019YFB2204704)the Fundamental Research Funds for the Central Universitiesthe Zhishan Scholar Program of Southeast University(2242022R40038).
文摘This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquidcrystal-based phased array(LCPA),including the design,over-the-air(OTA)in-array calibration,and experimental validation.The LCPA contains 16 phase-shifting radiating channels,each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter(LCPS)based on a loaded differential line structure.Thanks to its slow-wave properties,the LCPS exhibits a maximum phase-shifting range of more than 360°with a figure of merit of 78.3(°)·dB^(-1)based on a liquid crystal layer with a thickness of only 5μm.Furthermore,an automatic OTA calibration based on a state ergodic method is proposed,which enables the extraction of the phase-voltage curve of every individual LCPA channel.The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm,experimentally demonstrating a scanned circularly polarized beam from-40°to+40°with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB.The bandwidth of the LCPA,which satisfies the require-ments of port reflection(|S_(11)|)<-15 dB,an axial ratio(AR)<3 dB,beam squinting<3°,and a gain variation<2.2 dB,spans from 25.5 to 26.0 GHz.The total efficiency is about 34%,which represents a new state of the art.The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams,along with the systematic design and calibration methodology,holds potential promise for a variety of millimeter-wave applications.
基金supported by the National Natural Science Foundation of China(Grant No.61971117)the Natural Science Foundation of Hebei Province(Grant No.F2020501007)the S&T Program of Hebei(No.22377717D)。
文摘This paper considers a high energy efficiency dynamic connected(HEDC)structure,which promotes the practicability and reduces the power consumption of hybrid precoding system by lowresolution phase shifters(PSs).Based on the proposed structure,a new hybrid precoding algorithm is presented to optimize the energy efficiency,namely,HP-HEDC algorithm.Firstly,via a new defined effective optimal precoding matrix,the problem of optimizing the analog switch precoding matrix is formulated as a sparse representation problem.Thus,the optimal analog switch precoding matrix can be readily obtained by the branch-and-bound method.Then,the digital precoding matrix optimization problem is modeled as a dictionary update problem and solved by the method of optimal direction(MOD).Finally,the diagonal entries of the analog PS precoding matrix are optimized by exhaustive search independently since PS and antenna is one-to-one.Simulation results show that the HEDC structure enjoys low power consumption and satisfactory spectral efficiency.The proposed algorithm presents at least 50%energy efficiency improvement compared with other algorithms when the PS resolution is set as 3-bit.
文摘Barium strontium titanate/magnesia （BSTO/MgO） ferroeleetric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5 % on dielectric behaviors of BSTO/MgO composites were studied in terms of permittivity, loss tangent and tunability both at low and high frequencies. The dielectric constant of Y2O3 and Er2O3 doped samples decreases from 160 to 120, and the microwave loss of La2O3 and Er2O3 doped samples decreases from 8.2 x 10-3 to 6.8 x 10-3. Only La203 increases the tunability of BSTO/MgO system, from 13.6% to 14.8%. For the La2O3 doped sample, the value of tunability is more than 14% with the external DC field 4000 V·mm^-1 and the microwave loss at 2.47 GHz is 6.77 ×10^-3 and, hence, it can basically meet the requirements of phase shifters working at microwave frequencies. The influence mechanism was discussed preliminarily.
基金This work was supported by Chuan-Yu Cooperation Project(No.Cstc2020jscx-cy1hX0006)Chongqing Science and Technology Commission of China(Grant No.cstc2020jscx-msxm0099 and cstc2020jscx-msxm0100)Chongqing Natural Science Foundation of China(No.cstc2020jcyj-msxm3725).
文摘Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one of the basic tuning devices,the thermo-optic phase shifter(TOPS)plays an important role in all these applications.A TOPS with the merits of easy fabrication,low power consumption,small thermal time constant,low insertion loss,small footprint,and low crosstalk,is needed to improve the performance and lower the cost of the above applications.To meet these demands,various TOPS have been proposed and experimentally demonstrated on different foundry platforms In this paper,we review the state-of-the-art of TOPS,including metal heater,doped silicon,silicide,with silicon substrate undercut for heat insulation,folded waveguide structure,and multi-pass waveguide structure.We further compare these TOPSs and propose the directions of the future developments on TOPS.
基金supported by the National Natural Science Foundation of China(No.51806231)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB35000000).
文摘As an important component of the stirling-type pulse tube cryocooler(SPTC),an efficient phase shifter can significantly improve the cooling capacity.Compared to the common phase shifter,the active warm displacer(AWD)has a wider phase adjustment range and therefore can obtain a better phase relationship easily.Based on a two-stage thermal-coupled SPTC operating in the 20 K range,this paper studied the influence of the swept volume ratio between the compressor and displacer.The research found that the swept volume ratio changes the cooling capacity and efficiency of the cryocooler mainly by changing the phase difference between the pressure wave and the volume flow at the cold end.It was found from the results of the simulation and experiments that there is an optimal displacement of the displacer(Xd)of 2.5 mm and an optimal phase angle of 15°to obtain the highest cooling efficiency while the displacement of the compressor is constant.The cooling capacity at 20 K is 1.3 W while the input electrical power of the second stage compressor is 202 W,which indicates an overall relative Carnot efficiency(rCOP)of 0.055 in terms of input electrical power.In addition,due to the reasonable setting of precooling temperature and capacity,the swept volume ratio and phase at the maximum cooling capacity and maximum efficiency are consistent in this study.The research improves the understanding of phase shifters and has guiding significance for the optimization of the SPTC working below 20 K.
文摘The China Dark Matter Experiment （CDEX） is a low background experiment at China Jinping Under- ground Laboratory （CJPL） designed to directly detect dark matter with a high-purity germanium （HPGe） detector. In the second phase, CDEX-10, which has a 10 kg germanium array detector system, a liquid argon （LAr） anti- Compton active shielding and cooling system is proposed. To study the properties of the LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV γ rays at different positions. The good agreement between the experimental and simulation results has provided a reasonable understanding and determination of the important parameters such as the surviving fraction of the Ar2 excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.
文摘This paper proposed an X-band 6-bit passive phase shifter （PS） designed in 0.18 μm silicon-on-insulator （SOI） CMOS technology, which solves the key problem of high integration degree, low power, and a small size T/R module. The switched-topology is employed to achieve broadband and fiat phase shift. The ESD circuit and driver are also integrated in the PS. It covers the frequency band from 7.5 to 10.5 GHz with an EMS phase error less than 7.5%. The input and output VSWRs are less than 2 and the insertion loss （IL） is between 8-14 dB across the 7.5 to 10.5 GHz, with a maximum IL difference of 4 dB. The input 1 dB compression point （IP1dB） is 20 dBm.
