Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding shou...Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding should be long-travel, high-frequency and high-precision in non-circular precision turning, a new one-freedom flexure hinge structure is put forward to amplify the output displacement of piezoelectric actuator. Theoretical analysis is done on the static and dynamic characteristics of the structure, differential equations are presented, and it is also verified by the finite element method. It's proved by experiments that the output displacement of the structure is 293 μm and its resonant frequency is 312 Hz.展开更多
Using the concept of optical transformation, we report on an amplifying device, which can make an arbitrary object enlarged. Its potential application to small object identification and detection is foreseeable. The c...Using the concept of optical transformation, we report on an amplifying device, which can make an arbitrary object enlarged. Its potential application to small object identification and detection is foreseeable. The cylindrical anisotropic amplifying shell could be mimicked by radially symmetrical ＂sectors＂ alternating in composition between two profiles of isotropic dielectrics; the permittivity and permeability in each ＂sector＂ can be properly determined by the effective medium theory. Both the magnetic and nonmagnetic amplifying devices are validated by full-wave finite element simulations. Good amplifying performance is observed.展开更多
This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying （BRA） experiments and ...This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying （BRA） experiments and their variants. The numerical results are in good agreement with experiments.展开更多
WO_3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd^(3+)-doped tellurite-based glasses of Te O_2-Zn O-Na_2 O to improve the 1.32 μm band fluorescence emission. The ...WO_3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd^(3+)-doped tellurite-based glasses of Te O_2-Zn O-Na_2 O to improve the 1.32 μm band fluorescence emission. The absorption spectra,Raman spectra,1.32 μm band fluorescence spectra and differential scanning calorimeter(DSC) curves were measured,together with the Judd-Ofelt intensity parameters,stimulated emission and gain parameters were calculated to evaluate the effects of WO_3 amount on the glass structure and spectroscopic properties of 1.32 μm band fluorescence. It is shown that the introduction of an appropriate amount of WO_3 oxide can effectively improve the 1.32 μm band fluorescence intensity through the enhanced multi-phonon relaxation(MPR) processes between the excited levels of Nd^(3+). The results indicate that the prepared Nd^(3+)-doped tellurite glass with an appropriate amount of WO_3 oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.展开更多
A nonlinear amplifying loop mirror constructed from erbium-doped fiber is proposed for simultaneous amplification and compression of ultrashort fundamental solitons. Numerical simulations show that, the proposed devic...A nonlinear amplifying loop mirror constructed from erbium-doped fiber is proposed for simultaneous amplification and compression of ultrashort fundamental solitons. Numerical simulations show that, the proposed device performs efficient high-quality amplification and compression of solitons.展开更多
We discuss recent progress in using machine-learning(ML)-enabled inverse design techniques applied to photonic devices and components.Specifically,we highlight the design of optical sources,including fiber and semicon...We discuss recent progress in using machine-learning(ML)-enabled inverse design techniques applied to photonic devices and components.Specifically,we highlight the design of optical sources,including fiber and semiconductor lasers,as well as Raman and semiconductor optical amplifiers.Although inverse design approaches for optical detectors remain relatively underexplored,we examine optical layers,particularly metamaterial absorbers,as promising candidates for high-performance optical detection.In addition,we underscore advancements in inverse designing passive optical components,including beam splitters,gratings,and optical fibers.These optical blocks are fundamental in developing next-generation standalone optical communication systems and optical sensing networks,including integrated sensing and communication technologies.While categorizing various reported deep learning architectures across five paradigms,we offer a paradigm-based perspective that reveals how different ML techniques function within modern inverse design methods and enable fast,data-driven solutions that significantly reduce design time and computational demands compared with traditional optimization methods.展开更多
In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the com...In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the complex formula derivation in the traditional amplifier circuit design process,and the design process is more simple and intuitive.Besides,it only takes three steps to build the load modulation network(LMN) of two power amplifiers(PA) of the DPA.Besides,a capacitor is used to replace the parasitic parameters of the transistor,and the LMN designed in the two modes is used for exploration and comparison.Further more,the output impedance of the peaking PA is introduced to make the reflection coefficient trajectory on Smith chart lowfrequency dispersion so as to expand the bandwidth of the DPA at the output power back-off(OBO) level.It would not affect the performance of DPA in the saturation(SAT) state.In this way,a broadband DPA can be implemented easily.To validate the proposed design method,a broadband DPA operating from 1.9to 2.6 GHz is designed and measured based on the proposed method.Under the continuous-wave excitation,the fabricated DPA has a 6 dB OBO efficiency of 48%-56% and a SAT efficiency of 64%-73% from 1.75 to 2.45 GHz,and the peak output power is 48.9-49.8 dBm.展开更多
We propose an optimization method based on evolutionary computation for the design of broadband high-efficiency current-biased reverse load-modulation power amplifiers(CB-RLM PAs).First,given the reverse load-modulati...We propose an optimization method based on evolutionary computation for the design of broadband high-efficiency current-biased reverse load-modulation power amplifiers(CB-RLM PAs).First,given the reverse load-modulation characteristics of CB-RLM PAs,a comprehensive objective function is proposed that combines multi-state impedance trajectory constraints with in-band performance deviations.For the saturation and 6 dB power back-off(PBO)states,approximately optimal impedance regions on the Smith chart are derived using impedance constraint circles based on load-pull simulations.These regions are used together with in-band performance deviations(e.g.,saturated efficiency,6 dB PBO efficiency,and saturated output power)for matching network optimization and design.Second,a multi-objective evolutionary algorithm based on decomposition with adaptive weights,neighborhood,and global replacement is integrated with harmonic balance simulations to optimize design parameters and evaluate performance.Finally,to validate the proposed method,a broadband CB-RLM PA operating from 0.6 to 1.8 GHz is designed and fabricated.Measurement results show that the efficiencies at saturation,6 dB PBO,and 8 dB PBO all exceed 43.6%,with saturated output power being maintained at 40.9–41.5 dBm,which confirms the feasibility and effectiveness of the proposed broadband high-efficiency CB-RLM PA optimization and design approach.展开更多
The nonchemically amplified(nonCA)polymer resists,including ionic and nonionic types,have achieved higher resolution and smaller line edge roughness(LER)than traditional chemically amplified ones.However,for polymer r...The nonchemically amplified(nonCA)polymer resists,including ionic and nonionic types,have achieved higher resolution and smaller line edge roughness(LER)than traditional chemically amplified ones.However,for polymer resists,chain entanglement is an inevitable limitation for the further reduction of LER.To overcome this problem,it is logical to apply the nonCA concept to molecule-based resists due to their advantages of monodispersity and small size.To date,only a few examples of ionic sulfonium salts-based nonCA molecular glass resists(nonCAMGRs)have been reported.They demonstrated high resolution and small LER well,but their electron beam sensitivity seemed less than ideal.To our knowledge,non-ionic sulfoxime oxime esters-based molecular resists were not reported yet,which leaves room for new round of more in-depth reserch on nonCAMGRs.Here,employing the excellent spirobixanthene backbone,we have first designed non-ionic sulfoxime oxime esters-based nonCAMGRs X4-NI-tf and X4-NI-tfb,for comparison,sulfonium salts-based nonCAMGRs X4-I-otfdm was designed.All exhibit favorable thermal properties(T_(d,5%)>200°C)and filmforming capabilities(RMSs<0.4 nm).Via EBL,X4-I-otfdm achieved higher resolution(16 nm,LER 1.4 nm)than X4-NI-tf and X4-NI-tfb(20 nm,LER 1.6 nm).But contrast curve revealed that the sensitivity of X4-NI-tf and X4-NI-tfb(D_(100):370 and 350μC/cm^(2))was significantly higher than X4-I-otfdm(D_(100):3300μC/cm^(2)),demonstrating that the sensitivity of sulfoxime oxime esters exceeds that of sulfonium salts and introduction of bromine can further enhance the sensitivity;based on above,X4-NI-tfb exhibited the lowest Z-factor and demonstrated the best overall performance.We believe that nonCAMGRs based on sulfoxime oxime esters represent a strong candidate for high-performance photoresists.展开更多
A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete...A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition.展开更多
For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add c...For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add channels to the non-reciprocal optical device and the non-reciprocity can route optical signals and prevent the reverse flow of noise.Using the Scully–Lamb model and gain saturation effect,we accomplish dual-frequency non-reciprocal transmission by introducing nonlinearity into a linear array of four-mode resonators.The accomplishment is directly demonstrated by the non-reciprocal transmission phenomena present in the non-divergent peaks.For example,a directional cyclic amplifier is constructed with non-reciprocal units.Regarding potential applications,non-reciprocal optical systems can be employed in dual-frequency control,parallel information processing,photonic integrated circuits,optical devices and so on.展开更多
We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop m...We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop mirrors.By employing 100-m polarization-maintaining fiber(PMF)in the nonlinear loop,the fundamental repetition rate reaches 1.84 MHz and no practical limitation is found to further decrease the repetition rate.The filter used in the long loop not only suppresses Kelly sidebands of the solitons,but also eliminates the amplified spontaneous emission which exists widely in lowrepetition-rate ultrafast fiber lasers.The bandwidth of the filter is optimized by using a numerical model.The laser emits approximately 3-ps pulses with an energy of 17.4 p J,which is further boosted to 1.5μJ by using a fiber amplifier.展开更多
Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmissio...Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror （NOLM） and amplifier combinations, the present scheme permits significant increase of loop-mirror （amplifier） spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.展开更多
Lots of research efforts have been devoted to increase the transmission capacity in optical communications using orbital angular momentum(OAM)multiplexing.To enable long-haul OAM mode transmission,an in-line OAM fiber...Lots of research efforts have been devoted to increase the transmission capacity in optical communications using orbital angular momentum(OAM)multiplexing.To enable long-haul OAM mode transmission,an in-line OAM fiber amplifier is desired.A ring-core fiber(RCF)is considered to be a preferable design for stable OAM mode propagation in the fiber.Here,we demonstrate an OAM fiber amplifier based on a fabricated ring-core erbium-doped fiber(RC-EDF).We characterize the performance of the RC-EDF-assisted OAM fiber amplifier and demonstrate its use in OAM multiplexing communications with OAM modes carrying quadrature phase-shift keying(QPSK)and quadrature amplitude modulation(QAM)signals.The amplification of two OAM modes over four wavelengths is demonstrated in a data-carrying OAM-division multiplexing and wavelength-division multiplexing system.The obtained results show favorable performance of the RC-EDF-assisted OAM fiber amplifier.These demonstrations may open up new perspectives for long-haul transmission in capacity scaling fiber-optic communications employing OAM modes.展开更多
By considering the cross phase modulation （XPM） between the two orthogonal poparization components, the nonlinear birefringence and nonlinear polarization evolution （NPE） in highly-nonlinear fiber （HNLF）, as wel...By considering the cross phase modulation （XPM） between the two orthogonal poparization components, the nonlinear birefringence and nonlinear polarization evolution （NPE） in highly-nonlinear fiber （HNLF）, as well as the unequal evolutions of the state of polarization （SOP） between the clockwise （CW） and counter-clockwise （CCW） waves in a nonlinear amplifying loop mirror （NALM） are analyzed. It is pointed out that the traditional cosine expression is no longer valid for the power transmission of NALM due to uncompleted interference under the high power condition. The analytical expression considering NPE effect is derived, and the experimental result is presented.展开更多
Microstrip traveling wave tubes(TWTs)have garnered significant attention due to their potential applications in communication,defense,and industrial systems.This paper presents a compact W-band dual-channel TWT,utiliz...Microstrip traveling wave tubes(TWTs)have garnered significant attention due to their potential applications in communication,defense,and industrial systems.This paper presents a compact W-band dual-channel TWT,utilizing a U-shaped microstrip meander-line slow-wave structure(SWS).High-frequency characteristics are analyzed through simulation and cold tests.The results demonstrate that adjusting structural parameters effectively optimizes the S-parameters.Particle-in-cell(PIC)simulations with an 18.8 kV,0.1 A electron beam predict an output power of 18 W with a gain of 14 dB.Experimental measurements of S-parameters are conducted using three substrate materials:Rogers 5880,quartz,and diamond.The quartz substrate exhibits the closest agreement with simulation results.The results advance the development of the microstrip-based TWTs for high-data-rate communication systems.展开更多
In this paper,we have mainly studied the amplification effect of thulium-doped fiber amplifier(TDFA)at 2µm,and compared different amplification effects of the one-stage TDFA,two-stage TDFA and three-stage TDFA at...In this paper,we have mainly studied the amplification effect of thulium-doped fiber amplifier(TDFA)at 2µm,and compared different amplification effects of the one-stage TDFA,two-stage TDFA and three-stage TDFA at proper conditions.The simulation results show that within the effective threshold,with the increase of the pump power,the amplification effect of the optical amplifier improves,but the signal-to-noise ratio(SNR)of the output signal decreases,in order to balance the gain benefit and noise coefficient of TDFA,we can use a multi-stage amplification structure.Three-stage backward-pumped series 2.06µm TDFA,whose slope efficiency can achieve 11%at certain condition.At 5.2 W pump power,the output signal gain of 2µm TDFA exceeds 20 dB,and the output SNR is higher than 32 dB.In addition,the effect of the optimum length of thulium-doped fiber on the amplification performance of 2µm TDFA is also analyzed in this paper.These simulation results are important for the experiment and design of 2µm TDFA.展开更多
This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered ...This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.展开更多
In this paper,a high-gain inductorless LNA(low-noise amplifier)compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed.A composite resistor-capacitor feedback structure is employed to achieve ...In this paper,a high-gain inductorless LNA(low-noise amplifier)compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed.A composite resistor-capacitor feedback structure is employed to achieve a wide bandwidth matching range and good gain flatness.A second stage with a Darlington pair is used to increase the overall gain of the amplifier,while the gain of the first stage is reduced to reduce the overall noise.The amplifier is based on a 0.25μm SiGe BiCMOS process,and thanks to the inductorless circuit structure,the core circuit area is only 0.03 mm^(2).Test results show that the lowest noise figure(NF)in the operating band is 1.99 dB,the power gain reaches 29.7 dB,the S_(11)and S_(22)are less than-10 dB,the S_(12)is less than-30 dB,the IIP3 is 0.81dBm,and the OP_(1dB)is 10.27 dBm.The operating current is 31.18 mA at 3.8 V supply.展开更多
In the era of rapidly expanding wireless technologies,the push for larger spectrum efficiency and better signal integrity has intensified the need for high-efficient and low noise amplifiers(LNAs).A two-stage LNA base...In the era of rapidly expanding wireless technologies,the push for larger spectrum efficiency and better signal integrity has intensified the need for high-efficient and low noise amplifiers(LNAs).A two-stage LNA based on the GaAs/InGaAs pseudomorphic high electron mobility transistor(pHEMT)with a relatively large gate length of 2μm is designed for high-performance 2.4-GHz wireless communication.The I-V characteristic and two-port high-frequency S-parameter of the transistor are measured by on-wafer probing techniques.The results indicate that a discrete transistor with a gate size of 2μm×50μm can provide a maximum transconductance of 16 mS,corresponding to a maximum current-gain cut-off frequency of 7 GHz and maximum oscillation frequency of 8 GHz at the 1-V drain-source voltage.With the impedance matching networks based transmission line technique,an extended integrated layout structure is designed and simulated by using the momentum simulation tool embedded in Advanced Design System,to alleviate the trade-off between noise figure(NF)and gain of the circuit.The findings show that the transistor based on the GaAs/InGaAs technology is capable of delivering high performance with power consumption low to 16 mW,where the maximum simulated gain of 21.5 dB and minimum NF of 2.4 dB are achieved.In terms of linearity,the proposed LNA provides terrific output 1-dB compression of-3 dBm and output third-order intercept point values of 10 dBm.The bandwidth of 0.12 GHz and figure-of-merit of 12 are obtained,which are comparable to that of existing LNAs based on pHEMT.Such a device may benefit to accelerate the development of more robust and power-efficient front-end modules in modern wireless systems,especially for advancing performance-driven applications.展开更多
文摘Piezoelectric actuator has high stiffness, high frequency and infinite control precision, but a short output displacement which is often 1/1 000 of its length. In order to meet the requirements that tools feeding should be long-travel, high-frequency and high-precision in non-circular precision turning, a new one-freedom flexure hinge structure is put forward to amplify the output displacement of piezoelectric actuator. Theoretical analysis is done on the static and dynamic characteristics of the structure, differential equations are presented, and it is also verified by the finite element method. It's proved by experiments that the output displacement of the structure is 293 μm and its resonant frequency is 312 Hz.
基金Project supported by the Open Research Program in State Key Laboratory of Millimeter Waves,China (Grant No.K200802)the National Natural Science Foundation of China (Grant No.61302048)the Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions,China
文摘Using the concept of optical transformation, we report on an amplifying device, which can make an arbitrary object enlarged. Its potential application to small object identification and detection is foreseeable. The cylindrical anisotropic amplifying shell could be mimicked by radially symmetrical ＂sectors＂ alternating in composition between two profiles of isotropic dielectrics; the permittivity and permeability in each ＂sector＂ can be properly determined by the effective medium theory. Both the magnetic and nonmagnetic amplifying devices are validated by full-wave finite element simulations. Good amplifying performance is observed.
文摘This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying （BRA） experiments and their variants. The numerical results are in good agreement with experiments.
基金supported by the National Natural Science Foundation of China(No.61178063)the Natural Science Foundation of Ningbo City(No.2016A610061)+1 种基金the K.C.Wong Magna FundHu Lan Outstanding Doctoral Fund in Ningbo University
文摘WO_3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd^(3+)-doped tellurite-based glasses of Te O_2-Zn O-Na_2 O to improve the 1.32 μm band fluorescence emission. The absorption spectra,Raman spectra,1.32 μm band fluorescence spectra and differential scanning calorimeter(DSC) curves were measured,together with the Judd-Ofelt intensity parameters,stimulated emission and gain parameters were calculated to evaluate the effects of WO_3 amount on the glass structure and spectroscopic properties of 1.32 μm band fluorescence. It is shown that the introduction of an appropriate amount of WO_3 oxide can effectively improve the 1.32 μm band fluorescence intensity through the enhanced multi-phonon relaxation(MPR) processes between the excited levels of Nd^(3+). The results indicate that the prepared Nd^(3+)-doped tellurite glass with an appropriate amount of WO_3 oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.
基金The authors acknowledge the support of the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. PolyU5096/98E).
文摘A nonlinear amplifying loop mirror constructed from erbium-doped fiber is proposed for simultaneous amplification and compression of ultrashort fundamental solitons. Numerical simulations show that, the proposed device performs efficient high-quality amplification and compression of solitons.
基金the School of Engineering and Built Environment at Anglia Ruskin University,UK,for the supportthe support of IRC-CSS and the Electrical Engineering Department,KFUPM,Saudi Arabia。
文摘We discuss recent progress in using machine-learning(ML)-enabled inverse design techniques applied to photonic devices and components.Specifically,we highlight the design of optical sources,including fiber and semiconductor lasers,as well as Raman and semiconductor optical amplifiers.Although inverse design approaches for optical detectors remain relatively underexplored,we examine optical layers,particularly metamaterial absorbers,as promising candidates for high-performance optical detection.In addition,we underscore advancements in inverse designing passive optical components,including beam splitters,gratings,and optical fibers.These optical blocks are fundamental in developing next-generation standalone optical communication systems and optical sensing networks,including integrated sensing and communication technologies.While categorizing various reported deep learning architectures across five paradigms,we offer a paradigm-based perspective that reveals how different ML techniques function within modern inverse design methods and enable fast,data-driven solutions that significantly reduce design time and computational demands compared with traditional optimization methods.
基金National Natural Science Foundation of China (No. 62001061)。
文摘In this article,a graphic design method for broadband Doherty power amplifier(DPA) is proposed based on the basic principle of impedance matching with the help of Smith chart.The proposed graphic method avoids the complex formula derivation in the traditional amplifier circuit design process,and the design process is more simple and intuitive.Besides,it only takes three steps to build the load modulation network(LMN) of two power amplifiers(PA) of the DPA.Besides,a capacitor is used to replace the parasitic parameters of the transistor,and the LMN designed in the two modes is used for exploration and comparison.Further more,the output impedance of the peaking PA is introduced to make the reflection coefficient trajectory on Smith chart lowfrequency dispersion so as to expand the bandwidth of the DPA at the output power back-off(OBO) level.It would not affect the performance of DPA in the saturation(SAT) state.In this way,a broadband DPA can be implemented easily.To validate the proposed design method,a broadband DPA operating from 1.9to 2.6 GHz is designed and measured based on the proposed method.Under the continuous-wave excitation,the fabricated DPA has a 6 dB OBO efficiency of 48%-56% and a SAT efficiency of 64%-73% from 1.75 to 2.45 GHz,and the peak output power is 48.9-49.8 dBm.
基金supported by the National Natural Science Foundation of China(Nos.62171204,62171129,62001192).
文摘We propose an optimization method based on evolutionary computation for the design of broadband high-efficiency current-biased reverse load-modulation power amplifiers(CB-RLM PAs).First,given the reverse load-modulation characteristics of CB-RLM PAs,a comprehensive objective function is proposed that combines multi-state impedance trajectory constraints with in-band performance deviations.For the saturation and 6 dB power back-off(PBO)states,approximately optimal impedance regions on the Smith chart are derived using impedance constraint circles based on load-pull simulations.These regions are used together with in-band performance deviations(e.g.,saturated efficiency,6 dB PBO efficiency,and saturated output power)for matching network optimization and design.Second,a multi-objective evolutionary algorithm based on decomposition with adaptive weights,neighborhood,and global replacement is integrated with harmonic balance simulations to optimize design parameters and evaluate performance.Finally,to validate the proposed method,a broadband CB-RLM PA operating from 0.6 to 1.8 GHz is designed and fabricated.Measurement results show that the efficiencies at saturation,6 dB PBO,and 8 dB PBO all exceed 43.6%,with saturated output power being maintained at 40.9–41.5 dBm,which confirms the feasibility and effectiveness of the proposed broadband high-efficiency CB-RLM PA optimization and design approach.
基金supported by the National Natural Science Foundation of China(No.22278059,22174009,22078047)Fundamental Research Funds for the Central Universities(No.DUT24ZD119,DUT22LAB601 and DUT22LAB608).
文摘The nonchemically amplified(nonCA)polymer resists,including ionic and nonionic types,have achieved higher resolution and smaller line edge roughness(LER)than traditional chemically amplified ones.However,for polymer resists,chain entanglement is an inevitable limitation for the further reduction of LER.To overcome this problem,it is logical to apply the nonCA concept to molecule-based resists due to their advantages of monodispersity and small size.To date,only a few examples of ionic sulfonium salts-based nonCA molecular glass resists(nonCAMGRs)have been reported.They demonstrated high resolution and small LER well,but their electron beam sensitivity seemed less than ideal.To our knowledge,non-ionic sulfoxime oxime esters-based molecular resists were not reported yet,which leaves room for new round of more in-depth reserch on nonCAMGRs.Here,employing the excellent spirobixanthene backbone,we have first designed non-ionic sulfoxime oxime esters-based nonCAMGRs X4-NI-tf and X4-NI-tfb,for comparison,sulfonium salts-based nonCAMGRs X4-I-otfdm was designed.All exhibit favorable thermal properties(T_(d,5%)>200°C)and filmforming capabilities(RMSs<0.4 nm).Via EBL,X4-I-otfdm achieved higher resolution(16 nm,LER 1.4 nm)than X4-NI-tf and X4-NI-tfb(20 nm,LER 1.6 nm).But contrast curve revealed that the sensitivity of X4-NI-tf and X4-NI-tfb(D_(100):370 and 350μC/cm^(2))was significantly higher than X4-I-otfdm(D_(100):3300μC/cm^(2)),demonstrating that the sensitivity of sulfoxime oxime esters exceeds that of sulfonium salts and introduction of bromine can further enhance the sensitivity;based on above,X4-NI-tfb exhibited the lowest Z-factor and demonstrated the best overall performance.We believe that nonCAMGRs based on sulfoxime oxime esters represent a strong candidate for high-performance photoresists.
基金supported by the National Natural Science Foundation of China(Nos.U2167202,12225504,12005276)the Natural Science Foundation of Shandong Province(No.ZR2024QA172)the Fundamental Research Funds of Shandong University.
文摘A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition.
基金supported by the National Nature Science Foundation of China(Grant Nos.12475019 and 12073056)the Major National Science and Technology Project of China(Grant No.BX2024B054)+1 种基金National Lab of Solid State Microstructure of Nanjing University(Grant Nos.M35040,M35053,and M37014)the Natural Science Foundation of Shandong Province(Grant No.ZR2024MA038)。
文摘For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add channels to the non-reciprocal optical device and the non-reciprocity can route optical signals and prevent the reverse flow of noise.Using the Scully–Lamb model and gain saturation effect,we accomplish dual-frequency non-reciprocal transmission by introducing nonlinearity into a linear array of four-mode resonators.The accomplishment is directly demonstrated by the non-reciprocal transmission phenomena present in the non-divergent peaks.For example,a directional cyclic amplifier is constructed with non-reciprocal units.Regarding potential applications,non-reciprocal optical systems can be employed in dual-frequency control,parallel information processing,photonic integrated circuits,optical devices and so on.
基金supported by the National Key Research and Development Program (No. 2018YFB0407100)National Natural Science Foundation of China (Nos. 11434005 and 11621404)Key Project of Shanghai Education Commission (No. 2017-01-07-00-05-E00021)
文摘We report on environmentally stable long-cavity ultrashort erbium-doped fiber lasers,which self-start mode-locking at quite low thresholds by using spectrally filtered and phase-biased nonlinear amplifying long-loop mirrors.By employing 100-m polarization-maintaining fiber(PMF)in the nonlinear loop,the fundamental repetition rate reaches 1.84 MHz and no practical limitation is found to further decrease the repetition rate.The filter used in the long loop not only suppresses Kelly sidebands of the solitons,but also eliminates the amplified spontaneous emission which exists widely in lowrepetition-rate ultrafast fiber lasers.The bandwidth of the filter is optimized by using a numerical model.The laser emits approximately 3-ps pulses with an energy of 17.4 p J,which is further boosted to 1.5μJ by using a fiber amplifier.
基金This work was supported by the National NaturalScience Foundation of China (No. 60277016) and theGuangdong Natural Science Foundation of China (No.021357 and 04011761).
文摘Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors （NALMs）. We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror （NOLM） and amplifier combinations, the present scheme permits significant increase of loop-mirror （amplifier） spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.
基金This work was supported by the National Key R&D Program of China(2018YFB1801803)the National Natural Science Foundation of China(NSFC)(61761130082,11774116)+5 种基金the Royal Society-Newton Advanced Fellowship,the National Program for Support of Top-Notch Young Professionals,the Yangtze River Excellent Young Scholars Program,the Natural Science Foundation of Hubei Province of China(2018CFA048)the Key R&D Program of Guangdong Province(2018B030325002)the Open Fund of IPOC(BUPT)(IPOC2018A002)the Open Program from the State Key Laboratory of Advanced Optical Communication Systems and Networks(2020GZKF009)the Program for HUST Academic Frontier Youth Team(2016QYTD05)the Fundamental Research Funds for the Central Universities(2019kfyRCPY037).
文摘Lots of research efforts have been devoted to increase the transmission capacity in optical communications using orbital angular momentum(OAM)multiplexing.To enable long-haul OAM mode transmission,an in-line OAM fiber amplifier is desired.A ring-core fiber(RCF)is considered to be a preferable design for stable OAM mode propagation in the fiber.Here,we demonstrate an OAM fiber amplifier based on a fabricated ring-core erbium-doped fiber(RC-EDF).We characterize the performance of the RC-EDF-assisted OAM fiber amplifier and demonstrate its use in OAM multiplexing communications with OAM modes carrying quadrature phase-shift keying(QPSK)and quadrature amplitude modulation(QAM)signals.The amplification of two OAM modes over four wavelengths is demonstrated in a data-carrying OAM-division multiplexing and wavelength-division multiplexing system.The obtained results show favorable performance of the RC-EDF-assisted OAM fiber amplifier.These demonstrations may open up new perspectives for long-haul transmission in capacity scaling fiber-optic communications employing OAM modes.
文摘By considering the cross phase modulation （XPM） between the two orthogonal poparization components, the nonlinear birefringence and nonlinear polarization evolution （NPE） in highly-nonlinear fiber （HNLF）, as well as the unequal evolutions of the state of polarization （SOP） between the clockwise （CW） and counter-clockwise （CCW） waves in a nonlinear amplifying loop mirror （NALM） are analyzed. It is pointed out that the traditional cosine expression is no longer valid for the power transmission of NALM due to uncompleted interference under the high power condition. The analytical expression considering NPE effect is derived, and the experimental result is presented.
基金National Natural Science Foundation of China(62471097,62471115,62471101)Natural Science Foundation of Sichuan Province(2025ZNSFSC0537)Stable Support Porject of 12th Research Institute of China Electronics Technology Group Corporation。
文摘Microstrip traveling wave tubes(TWTs)have garnered significant attention due to their potential applications in communication,defense,and industrial systems.This paper presents a compact W-band dual-channel TWT,utilizing a U-shaped microstrip meander-line slow-wave structure(SWS).High-frequency characteristics are analyzed through simulation and cold tests.The results demonstrate that adjusting structural parameters effectively optimizes the S-parameters.Particle-in-cell(PIC)simulations with an 18.8 kV,0.1 A electron beam predict an output power of 18 W with a gain of 14 dB.Experimental measurements of S-parameters are conducted using three substrate materials:Rogers 5880,quartz,and diamond.The quartz substrate exhibits the closest agreement with simulation results.The results advance the development of the microstrip-based TWTs for high-data-rate communication systems.
基金supported by the Natural Science Foundation of Guangdong Province(Nos.2023A1515010093)the Shenzhen Fundamental Research Program(Nos.JCYJ20220809170611004,20231121110828001 and 20231121113641002)the Taipei University of Technology-Shenzhen University Joint Research Program(No.2024001).
文摘In this paper,we have mainly studied the amplification effect of thulium-doped fiber amplifier(TDFA)at 2µm,and compared different amplification effects of the one-stage TDFA,two-stage TDFA and three-stage TDFA at proper conditions.The simulation results show that within the effective threshold,with the increase of the pump power,the amplification effect of the optical amplifier improves,but the signal-to-noise ratio(SNR)of the output signal decreases,in order to balance the gain benefit and noise coefficient of TDFA,we can use a multi-stage amplification structure.Three-stage backward-pumped series 2.06µm TDFA,whose slope efficiency can achieve 11%at certain condition.At 5.2 W pump power,the output signal gain of 2µm TDFA exceeds 20 dB,and the output SNR is higher than 32 dB.In addition,the effect of the optimum length of thulium-doped fiber on the amplification performance of 2µm TDFA is also analyzed in this paper.These simulation results are important for the experiment and design of 2µm TDFA.
基金the postdoctoral research grant received from the University of Glasgow for the partial financial support for this research work。
文摘This paper introduces damping amplifier friction vibration absorbers(DAFVAs),compound damping amplifier friction vibration absorbers(CDAFVAs),nested damping amplifier friction vibration absorbers(NDAFVAs),and levered damping amplifier friction vibration absorbers(LDAFVAs)for controlling the structural vibrations and addressing the limitations of conventional tuned mass dampers(TMDs)and frictiontuned mass dampers(FTMDs).The closed-form analytical solution for the optimized design parameters is obtained using the H_(2)and H_(∞)optimization approaches.The efficiency of the recently established closed-form equations for the optimal design parameters is confirmed by the analytical examination.The closed form formulas for the dynamic responses of the main structure and the vibration absorbers are derived using the transfer matrix formulations.The foundation is provided by the harmonic and random-white noise excitations.Moreover,the effectiveness of the innovative dampers has been validated through numerical analysis.The optimal DAFVAs,CDAFVAs,NDAFVAs,and LDAFVAs exhibit at least 30%lower vibration reduction capacity compared with the optimal TMD.To demonstrate the effectiveness of the damping amplification mechanism,the novel absorbers are compared with a conventional FTMD.The results show that the optimized novel absorbers achieve at least 91%greater vibration reduction than the FTMD.These results show how the suggested designs might strengthen the structure's resilience to dynamic loads.
基金funded by the Science,Technology and Innovation Commission of Shenzhen Municipality(JCYJ20220818101001003)。
文摘In this paper,a high-gain inductorless LNA(low-noise amplifier)compatible with multiple communication protocols from 0.1 to 5.1 GHz is proposed.A composite resistor-capacitor feedback structure is employed to achieve a wide bandwidth matching range and good gain flatness.A second stage with a Darlington pair is used to increase the overall gain of the amplifier,while the gain of the first stage is reduced to reduce the overall noise.The amplifier is based on a 0.25μm SiGe BiCMOS process,and thanks to the inductorless circuit structure,the core circuit area is only 0.03 mm^(2).Test results show that the lowest noise figure(NF)in the operating band is 1.99 dB,the power gain reaches 29.7 dB,the S_(11)and S_(22)are less than-10 dB,the S_(12)is less than-30 dB,the IIP3 is 0.81dBm,and the OP_(1dB)is 10.27 dBm.The operating current is 31.18 mA at 3.8 V supply.
基金supported by Engineering and Physical Sciences Research Council(EPSRC)under Grant No.EP/P006973/1.
文摘In the era of rapidly expanding wireless technologies,the push for larger spectrum efficiency and better signal integrity has intensified the need for high-efficient and low noise amplifiers(LNAs).A two-stage LNA based on the GaAs/InGaAs pseudomorphic high electron mobility transistor(pHEMT)with a relatively large gate length of 2μm is designed for high-performance 2.4-GHz wireless communication.The I-V characteristic and two-port high-frequency S-parameter of the transistor are measured by on-wafer probing techniques.The results indicate that a discrete transistor with a gate size of 2μm×50μm can provide a maximum transconductance of 16 mS,corresponding to a maximum current-gain cut-off frequency of 7 GHz and maximum oscillation frequency of 8 GHz at the 1-V drain-source voltage.With the impedance matching networks based transmission line technique,an extended integrated layout structure is designed and simulated by using the momentum simulation tool embedded in Advanced Design System,to alleviate the trade-off between noise figure(NF)and gain of the circuit.The findings show that the transistor based on the GaAs/InGaAs technology is capable of delivering high performance with power consumption low to 16 mW,where the maximum simulated gain of 21.5 dB and minimum NF of 2.4 dB are achieved.In terms of linearity,the proposed LNA provides terrific output 1-dB compression of-3 dBm and output third-order intercept point values of 10 dBm.The bandwidth of 0.12 GHz and figure-of-merit of 12 are obtained,which are comparable to that of existing LNAs based on pHEMT.Such a device may benefit to accelerate the development of more robust and power-efficient front-end modules in modern wireless systems,especially for advancing performance-driven applications.
