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
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
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
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
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,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
Dual-output power amplifiers(PAs)have shown great potential in the area of radar,satellite and wireless communication systems.However,the flexibility of the power allocation in a dual-output PA without sacrificing eff...Dual-output power amplifiers(PAs)have shown great potential in the area of radar,satellite and wireless communication systems.However,the flexibility of the power allocation in a dual-output PA without sacrificing efficiency and circuit complexity still needs further investigation.This paper presents a digitally dual-input dual-output(DIDO)PA with reconfigurable modes for power allocation application.The proposed DIDO PA is consist of two identical sub-amplifiers and a 90◦coupler,showing a simple circuit topology.The input amplitudes of the two sub-amplifiers and their phase difference is dynamically controlled leveraging on the dual-input technique,leading to reconfigurable operation modes from power allocation to Doherty.In the power allocation mode,flexible power allocation between two output ports can be obtained by the DIDO PA without sacrificing drain efficiency(DE).On the other hand,flexible power transferring and enhanced back-off DE can be simultaneously achieved by the DIDO PA when it is in the Doherty mode.As a proof of concept,a DIDO PA operating at 2.4 GHz is fabricated and measured in this paper.In the power allocation mode,the DIDO PA achieves a DE of more than 71.8%with a total output power of larger than 44 dBm.Moreover,when the DIDO PA operates in the Doherty mode,it could deliver a maximum output power of more than 44 dBm with a saturation DE of more than 73.9%and a 6 dB back-off DE of more than 61.2%.展开更多
A cavity magnonic oscillator uses the coupling of a planar transmission line oscillator(cavity) and spin excitations(magnons) in a ferrimagnetic material to achieve superior frequency stability and reduced phase noise...A cavity magnonic oscillator uses the coupling of a planar transmission line oscillator(cavity) and spin excitations(magnons) in a ferrimagnetic material to achieve superior frequency stability and reduced phase noise. Like many low phase noise oscillators, a cavity magnonic oscillator faces the challenge that its narrow resonance profile is not well suited for injection locking amplification. This work presents an improved design for such an oscillator configured as an injection locking amplifier(ILA) with an extended lock range. The proposed design features a two-stage architecture, consisting of a pre-amplification oscillator and a cavity magnonic oscillator, separated by an isolator to prevent backward locking.By optimizing the circuit parameters of each stage, the proposed design achieved an order of magnitude increase in lock range, when compared to its predecessors, all while preserving the phase noise quality of the input, making it well-suited for narrowband, sensitive signal amplification. Furthermore, this work provides a method for using oscillators with high spectral purity as injection locking amplifiers.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
Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithiu...Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithium niobate waveguide amplifier achieving>10 dB off-chip(fiber-to-fiber)net gain and>20 mW fiber-output amplified power is demonstrated,thanks to the low-propagation-loss waveguides and robust waveguide edge-couplers prepared by the photolithography assisted chemomechanical etching technique.Systematic investigation on the fabricated waveguide amplifiers reveals remarkable optical gain around the peak wavelength of 1532 nm as well as the low fiber-coupling loss of-1.2 dB/facet.A fiber Bragg-grating based waveguide laser is further demonstrated using the fabricated waveguide amplifier as the external gain chip,which generates>2 mW off-chip power continuous-wave lasing around the gain peak at 1532 nm.The unambiguous demonstration of fiber-to-fiber net gain of the erbium-doped thinfilm lithium niobate(TFLN)waveguide amplifier as well as its external gain chip application will benefit diverse fields demanding scalable gain elements with highspeed tunability.展开更多
In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different ph...In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different phase profiles,can be transformed into each other.In principle,the LP and OAM modes have a different mode spatial intensity distribution and a gain difference for FM-EDF amplifiers.How to analyze and characterize the differential mode-bases gain(DMBG)is important,but still an issue.We build,for the first time to our knowledge,a local analysis model composed of discrete elements of the FM-EDF cross section in areas of mode spatial intensity distribution azimuthal variation.Using the model of the two mode bases,analysis of local particle number distribution and detailed description of the local gain difference are realized,and the overall gain difference between the two mode bases is obtained.By building an amplifier system based on mode phase profile controlling,the gain of two mode bases is characterized experimentally.The measured DMBG is∼0.8 dB in the second-order mode,which is consistent with the simulation result.This result provides a potential way to reduce the mode gain difference in the FM-EDF,which is important in improving the performance of the SDM communication system.展开更多
Periodic metal nanoarrays serving as cavities can support directional-tunable amplified spontaneous emission that goes beyond the diffraction limit due to the hybrid states of surface plasmons and Bloch surface waves....Periodic metal nanoarrays serving as cavities can support directional-tunable amplified spontaneous emission that goes beyond the diffraction limit due to the hybrid states of surface plasmons and Bloch surface waves.Most of these modes'interactions remain within the weak coupling regime,yet strong coupling is also anticipated to occur.In this work,we present an intriguing case of amplified spontaneous emission(ASE),amplified by the splitting upper polariton mode within a strong coupling system,stemming from a square lattice of plasmonic cone lattices(PCLs).The PCLs are fabricated using an anodized aluminum oxide membrane(AAO),which facilitates strong coupling between surface plasmons and Bloch surface wave modes,with the maximum Rabi splitting observed at 0.258 eV for the sample with an aspect ratio of 0.33.A 13.5-fold increase in amplified spontaneous emission is recorded when the emission from Nile Red coincides with this flat energy branch of upper polariton,which exhibits a high photon density of states.Reduced group velocity can prolong photon lifetime and boost the probability of light-matter interaction.The observed ASE phenomenon in this strong coupling plasmonic system widens the scope for applications in nanolasing and polariton lasing.展开更多
The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simu...The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.展开更多
We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training ph...We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training phase, the connection weights of the unified NN are updated again in verification phase according to error between the predicted and target gains to eliminate the inherent error of the NNs. The simulation results show that the mean of root mean square error(RMSE) and maximum error of gains are 0.131 d B and 0.281 d B, respectively. It shows that the method can realize adaptive adjustment function of FRA gain with high accuracy.展开更多
MEMS压电式水听器需要使用模拟前端对产生的信号进行预处理,但当前水听器的模拟前端大都基于板级方案,检测性能、集成度和适用范围有待提高,需要设计一款模拟前端专用芯片实现MEMS压电式水听器系统的微型化、阵列化。首先根据MEMS压电...MEMS压电式水听器需要使用模拟前端对产生的信号进行预处理,但当前水听器的模拟前端大都基于板级方案,检测性能、集成度和适用范围有待提高,需要设计一款模拟前端专用芯片实现MEMS压电式水听器系统的微型化、阵列化。首先根据MEMS压电式水听器的特点和需求,确定了芯片的系统架构;其次设计了自动增益控制环路、可编程增益放大器和频带可变低通滤波器,拓宽了芯片的适用范围;最后将斩波结合自调零的降噪技术用于芯片,以满足水听器低噪声测量的要求。基于0.18μm CMOS工艺对模拟前端芯片进行设计,后仿真结果显示所设计电路在1 k Hz时等效输入噪声功率谱密度为59 n V/√Hz,输入电荷量与输出电压的非线性误差小于1.26%。验证了模拟前端专用芯片可以对MEMS压电式水听器产生的低频微弱信号实现低噪声放大。展开更多
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
The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent L...The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.展开更多
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 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 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 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 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supported in part by the National Natural Science Foundation of China(No.62201100).
文摘Dual-output power amplifiers(PAs)have shown great potential in the area of radar,satellite and wireless communication systems.However,the flexibility of the power allocation in a dual-output PA without sacrificing efficiency and circuit complexity still needs further investigation.This paper presents a digitally dual-input dual-output(DIDO)PA with reconfigurable modes for power allocation application.The proposed DIDO PA is consist of two identical sub-amplifiers and a 90◦coupler,showing a simple circuit topology.The input amplitudes of the two sub-amplifiers and their phase difference is dynamically controlled leveraging on the dual-input technique,leading to reconfigurable operation modes from power allocation to Doherty.In the power allocation mode,flexible power allocation between two output ports can be obtained by the DIDO PA without sacrificing drain efficiency(DE).On the other hand,flexible power transferring and enhanced back-off DE can be simultaneously achieved by the DIDO PA when it is in the Doherty mode.As a proof of concept,a DIDO PA operating at 2.4 GHz is fabricated and measured in this paper.In the power allocation mode,the DIDO PA achieves a DE of more than 71.8%with a total output power of larger than 44 dBm.Moreover,when the DIDO PA operates in the Doherty mode,it could deliver a maximum output power of more than 44 dBm with a saturation DE of more than 73.9%and a 6 dB back-off DE of more than 61.2%.
基金funded by NSERC Discovery Grants, NSERC Discovery Accelerator Supplements, Innovation Proof-of-Concept Grant of Research Manitoba, and Faculty of Science Research Innovation and Commercialization Grant of University of Manitoba (C.-M.H.)。
文摘A cavity magnonic oscillator uses the coupling of a planar transmission line oscillator(cavity) and spin excitations(magnons) in a ferrimagnetic material to achieve superior frequency stability and reduced phase noise. Like many low phase noise oscillators, a cavity magnonic oscillator faces the challenge that its narrow resonance profile is not well suited for injection locking amplification. This work presents an improved design for such an oscillator configured as an injection locking amplifier(ILA) with an extended lock range. The proposed design features a two-stage architecture, consisting of a pre-amplification oscillator and a cavity magnonic oscillator, separated by an isolator to prevent backward locking.By optimizing the circuit parameters of each stage, the proposed design achieved an order of magnitude increase in lock range, when compared to its predecessors, all while preserving the phase noise quality of the input, making it well-suited for narrowband, sensitive signal amplification. Furthermore, this work provides a method for using oscillators with high spectral purity as injection locking amplifiers.
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.
基金financial supports from National Key R&D Program of China(Grant No.2022YFA1205100,2022YFA1404600)National Natural Science Foundation of China(Grant Nos.12192251,12334014,12474325,12134001,12304418,12474378,12274133,12174107,12174113,12274130)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Fundamental Research Funds for the Central Universities,the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(No.2023nmc005).
文摘Miniaturized erbium-doped waveguide amplifiers attracted great interests in recent decades due to their high gain-efficiency and function-scalability in the telecom C-band.In this work,an erbium-doped thin film lithium niobate waveguide amplifier achieving>10 dB off-chip(fiber-to-fiber)net gain and>20 mW fiber-output amplified power is demonstrated,thanks to the low-propagation-loss waveguides and robust waveguide edge-couplers prepared by the photolithography assisted chemomechanical etching technique.Systematic investigation on the fabricated waveguide amplifiers reveals remarkable optical gain around the peak wavelength of 1532 nm as well as the low fiber-coupling loss of-1.2 dB/facet.A fiber Bragg-grating based waveguide laser is further demonstrated using the fabricated waveguide amplifier as the external gain chip,which generates>2 mW off-chip power continuous-wave lasing around the gain peak at 1532 nm.The unambiguous demonstration of fiber-to-fiber net gain of the erbium-doped thinfilm lithium niobate(TFLN)waveguide amplifier as well as its external gain chip application will benefit diverse fields demanding scalable gain elements with highspeed tunability.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0706300)the National Natural Science Foundation of China(Grant Nos.U22B2010,62035018,and U2001601)+1 种基金the Program of Marine Economy Development Special Fund(Six Marine Industries)under the Department of Natural Resources of Guangdong Province(Grant No.GDNRC[2024]16)the project supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP231).
文摘In a few-mode erbium-doped fiber(FM-EDF),which is a key section in a space-division multiplexing(SDM)communication system,linearly polarized(LP)and orbital angular momentum(OAM)modes,as twomode bases with different phase profiles,can be transformed into each other.In principle,the LP and OAM modes have a different mode spatial intensity distribution and a gain difference for FM-EDF amplifiers.How to analyze and characterize the differential mode-bases gain(DMBG)is important,but still an issue.We build,for the first time to our knowledge,a local analysis model composed of discrete elements of the FM-EDF cross section in areas of mode spatial intensity distribution azimuthal variation.Using the model of the two mode bases,analysis of local particle number distribution and detailed description of the local gain difference are realized,and the overall gain difference between the two mode bases is obtained.By building an amplifier system based on mode phase profile controlling,the gain of two mode bases is characterized experimentally.The measured DMBG is∼0.8 dB in the second-order mode,which is consistent with the simulation result.This result provides a potential way to reduce the mode gain difference in the FM-EDF,which is important in improving the performance of the SDM communication system.
基金financial supports from National Natural Science Foundation of China(No.61905051)Natural Science Foundation of Heilongjiang Province(No.LH2020F027).
文摘Periodic metal nanoarrays serving as cavities can support directional-tunable amplified spontaneous emission that goes beyond the diffraction limit due to the hybrid states of surface plasmons and Bloch surface waves.Most of these modes'interactions remain within the weak coupling regime,yet strong coupling is also anticipated to occur.In this work,we present an intriguing case of amplified spontaneous emission(ASE),amplified by the splitting upper polariton mode within a strong coupling system,stemming from a square lattice of plasmonic cone lattices(PCLs).The PCLs are fabricated using an anodized aluminum oxide membrane(AAO),which facilitates strong coupling between surface plasmons and Bloch surface wave modes,with the maximum Rabi splitting observed at 0.258 eV for the sample with an aspect ratio of 0.33.A 13.5-fold increase in amplified spontaneous emission is recorded when the emission from Nile Red coincides with this flat energy branch of upper polariton,which exhibits a high photon density of states.Reduced group velocity can prolong photon lifetime and boost the probability of light-matter interaction.The observed ASE phenomenon in this strong coupling plasmonic system widens the scope for applications in nanolasing and polariton lasing.
文摘The noise feature of a single-mode class-A laser amplifier is investigated by solving the Maxwell–Bloch equations of motion in the presence of the fluctuation force of cavity Langevin.The aim is to calculate the simultaneous fluctuations that are superimposed on the amplitude and phase of the cavity electric field, as well as the atomic population inversion. The correlation function of these fluctuations yields the amplitude, phase, and spontaneous emission noise fluxes, respectively. The amplitude and spontaneous emission noise fluxes exhibit the Lorentzian profiles in both the below-threshold state and the injection-locking region of the above-threshold state. While noise is typically viewed negatively in science and engineering, this research highlights its positive role as a valuable tool for measuring the optical properties of a laser amplifier. For instance, the degree of first-order temporal coherence(DFOTC) is derived by taking the Fourier transform of the amplitude noise flux. The damping rate of DFOTC is associated with the coherence time of the light emitted by the laser amplifier. Furthermore, the uncertainty relation between noise bandwidth and coherence time is confirmed. Finally, it is demonstrated that the input pumping noise flux, together with the output amplitude and spontaneous emission noise fluxes, satisfy the principle of flux conservation.
基金supported by the Natural Science Research Project of Colleges and Universities in Anhui Province (No.KJ2021A0479)the Science Research Program of Anhui University of Finance and Economics (No.ACKYC22082)。
文摘We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training phase, the connection weights of the unified NN are updated again in verification phase according to error between the predicted and target gains to eliminate the inherent error of the NNs. The simulation results show that the mean of root mean square error(RMSE) and maximum error of gains are 0.131 d B and 0.281 d B, respectively. It shows that the method can realize adaptive adjustment function of FRA gain with high accuracy.
文摘MEMS压电式水听器需要使用模拟前端对产生的信号进行预处理,但当前水听器的模拟前端大都基于板级方案,检测性能、集成度和适用范围有待提高,需要设计一款模拟前端专用芯片实现MEMS压电式水听器系统的微型化、阵列化。首先根据MEMS压电式水听器的特点和需求,确定了芯片的系统架构;其次设计了自动增益控制环路、可编程增益放大器和频带可变低通滤波器,拓宽了芯片的适用范围;最后将斩波结合自调零的降噪技术用于芯片,以满足水听器低噪声测量的要求。基于0.18μm CMOS工艺对模拟前端芯片进行设计,后仿真结果显示所设计电路在1 k Hz时等效输入噪声功率谱密度为59 n V/√Hz,输入电荷量与输出电压的非线性误差小于1.26%。验证了模拟前端专用芯片可以对MEMS压电式水听器产生的低频微弱信号实现低噪声放大。
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.
文摘The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.
