High-Power Raman Soliton Generation at 1.7 μm in All-Fiber Polarization-Maintaining Erbium-Doped Amplifier

An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.

Broadband Dual-Input Doherty Power Amplifier Design Based on a Simple Adaptive Power Dividing Ratio Function

In this paper,a simple adaptive power dividing function for the design of a dual-input Doherty power amplifier(DPA)is presented.In the presented approaches,the signal separation function(SSF)at different frequency points can be characterized by a polynomial.And in the practical test,the coefficients of SSF can be determined by measuring a small number of data points of input power.Same as other dualinput DPAs,the proposed approach can also achieve high output power and back-off efficiency in a broadband operation band by adjusting the power distribution ratio flexibly.Finally,a 1.5-2.5 GHz highefficiency dual-input Doherty power amplifier is implemented according to this approach.The test results show that the peak power is 48.6-49.7d Bm,and the 6-d B back-off efficiency is 51.0-67.0%,and the saturation efficiency is 52.4-74.6%.The digital predistortion correction is carried out at the frequency points of 1.8/2.1GHz,and the adjacent channel power ratio is lower than-54.5d Bc.Simulation and experiment results can verify the effectiveness and correctness of the proposed method.

Harmonic balance simulation of the influence of component uniformity and reliability on the performance of a Josephson traveling wave parametric amplifier

A Josephson traveling wave parametric amplifier(JTWPA),which is a quantum-limited amplifier with high gain and large bandwidth,is the core device of large-scale measurement and control systems for quantum computing.A typical JTWPA consists of thousands of Josephson junctions connected in series to form a transmission line and hundreds of shunt LC resonators periodically loaded along the line for phase matching.Because the variation of these capacitors and inductors can be detrimental to their high-frequency characteristics,the fabrication of a JTWPA typically necessitates precise processing equipment.To guide the fabrication process and further improve the design for manufacturability,it is necessary to understand how each electronic component affects the amplifier.In this paper,we use the harmonic balance method to conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of a JTWPA.The results provide insightful and scientific guidance for device design and fabrication processes.

Three-channel CMOS transimpedance amplifier for LiDAR sensor receiver

For time-of-flight(TOF)light detection and ranging(LiDAR),a three-channel high-performance transimpedance amplifier(TIA)with high immunity to input load capacitance is presented.A regulated cascade(RGC)as the input stage is at the core of the complementary metal oxide semiconductor(CMOS)circuit chip,giving it more immunity to input photodiode detectors.A simple smart output interface acting as a feedback structure,which is rarely found in other designs,reduces the chip size and power consumption simultaneously.The circuit is designed using a 0.5μm CMOS process technology to achieve low cost.The device delivers a 33.87 dB?transimpedance gain at 350 MHz.With a higher input load capacitance,it shows a-3 dB bandwidth of 461 MHz,indicating a better detector tolerance at the front end of the system.Under a 3.3 V supply voltage,the device consumes 5.2 mW,and the total chip area with three channels is 402.8×597.0μm2(including the test pads).

Design and performance of a high-speed and low-noise preamplifier for SiPM

Considering the R&D for upgrading the K^(0)_(L) andμdetectors in the Belle II experiment using a scintillator and silicon pho-tomultiplier(SiPM),we designed a compact high-speed and low-noise preamplifier.The preamplifier demonstrated a good gain stability,bandwidth of 426 MHz,baseline noise level ofσ≈0.6 mV,dynamic range of up to170 mV of the input signal amplitude,good time resolution of 20 ps,and it can be comprehensively applied to SiPMs.Adopting pole-zero-cancelation in the preamplifier reduces both the rise and fall times of the SiPM signal,which can significantly improve the time resolution and reduce the pile-up when using a large SiPM or an array of SiPMs.Various combinations of the preamplifier and several types of SiPMs demonstrated time resolutions better than 50 ps for most cases;when the number of detected photons was larger than 60,a time resolution of approximately 25 ps was achieved.

Capacitance Sensing and Software-Realized Lock-in Amplifier for the Electromagnetically Levitated Micro Gyroscope

In the novel prototype of micro-gyroscope structure,the new configured capacitance sensing scheme for the micro gyroscope was analyzed and the virtual instrument based detection scheme was implemented.The digital lock-in amplifier was employed in the capacitance detection to restrain the noise interference.The capacitance analysis shows that 1 fF capacitance variation corresponds to 0.1 degree of the turn angle.The differential capacitance bridge and the charge integral amplifier were used as the front signal input interface.In the implementation of digital lock-in amplifier,a new routine which warranted the exactly matching of the reference phase to signal phase was proposed.The result of the experiment shows that digital lock-in amplifier can greatly eliminate the noise in the output signal.The non linearity of the turn angle output is 2.3% and the minimum resolution of turn angle is 0.04 degrees.The application of the software demodulation in the signal detection of micro-electro-mechanical-system(MEMS)device is a new attempt,and it shows the prospective for a high-performance application.

Impact of amplified spontaneous emission noise on the SRS threshold of high-power fiber amplifiers

Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation results confirm that ASE noise in the Raman wavelength band could reduce the SRS threshold of high-power fiber amplifiers significantly.As for ASE noise originated the main amplifier,it becomes stronger and reduces the SRS threshold at shorter operation wavelength below 1052 nm.As for ASE noise originated from the seed laser,it reduces the SRS threshold at different operation wavelength under the condition that the Raman ratio is over-90 dB in the seed laser.The theoretical method and results in this work could provide a well reference to extend the operation wavelength of high-power fiber lasers.

Digital Lock-in Amplifier Based on Microcontroller

与微控制器实现高划算、高度综合的数字占据放大器的一个方法被讨论。并且数字占据放大器对测量低频率的弱 signal.Digital 更合适信号顺序通过在信号时期的一个整数数字上测量的采样信号被获得，但是数字参考顺序通过数学操作被获得，然后数字的阶段敏感察觉能被计算数字信号顺序和数字引用 sequence.In 增加的跨关联的函数实现，频率反应和阶段字符数字最后，设计数字占据放大器被完成。试验性的结果证明数字占据放大器能被用于与低 ignal-to-noise 比率测量弱信号。

Lock-in-Amplifier Model for Analyzing the Behavior of Signal Harmonics in Magnetic Particle Imaging

The purpose of this study was to present a lock-in-amplifier model for analyzing the behavior of signal harmonics in magnetic particle imaging (MPI) and some simulation results based on this model. In the lock-in-amplifier model, the signal induced by magnetic nanoparticles (MNPs) in a receiving coil was multiplied with a reference signal, and was then fed through a low-pass filter to extract the DC component of the signal (output signal). The MPI signal was defined as the mean of the absolute value of the output signal. The magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively, and the strength of the selection magnetic field (SMF) in MPI was assumed to be given by the product of the gradient strength of the SMF and the distance from the field-free region (x). In addition, Gaussian noise was added to the signal induced by MNPs using normally-distributed random numbers. The relationships between the MPI signal and x were calculated for the odd- and even-numbered harmonics and were investigated for various time constants of the low-pass filter used in the lock-in amplifier and particle sizes and their distributions of MNPs. We found that the behavior of the MPI signal largely depended on the time constant of the low-pass filter and the particle size of MNPs. This lock-in-amplifier model will be useful for better understanding, optimizing, and developing MPI, and for designing MNPs appropriate for MPI.

Improving source-in-the-middle continuous-variable quantum key distribution using a heralded hybrid linear amplifier

A hybrid linear amplifier is inserted at the output of the source-in-the-middle distribution protocol to overcome the shortcomings of the transmission distance.The modified protocol aims to maintain a high key rate for long-distance transmission under high noise.It has the potential to significantly broaden the application range of the continuous variable quantum key distribution protocol.The effects of amplifier parameters and noise on the modified protocol are analyzed in detail with regard to applying it to a practical system.To make the simulation more realistic,the effect of finite size on the new protocol is taken into account.It will serve as a guideline for the future use of hybrid linear amplifiers.Different parameters can be adjusted to achieve the best performance for key rates of different quantum channels.

5G Wideband Bandpass Filtering Power Amplifiers Based on a Bandwidth-Extended Bandpass Matching Network

In this paper,a 5G wideband power amplifier(PA)with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network(MN).In this structure,the bandwidth(θ_(C))is defined as a variable in the closedform equations provided by the microstrip bandpass filter.It can be extended over a wide range only by changing the characteristic impedances of the structure.Different from the other wideband MNs,the extension of bandwidth does not increase the complexity of the structure(order n is fixed).In addition,based on the bandwidth-extended structure,the wideband design of bandpass filtering PA is not limited to the fixed bandwidth of the specific filter structure.The theoretical analysis of the MN and the design flow of the PA are provided in this design.The fabricated bandpass filtering PA can support almost one-octave bandwidth(2-3.8 GHz),covering the two 5G bands(n41 and n78).The drain efficiency of 47%-60%and output power higher than 40 dBm are measured.Good frequency selectivity in S-parameter measurements can be observed.

Piezomagnetic vibration energy harvester with an amplifier

We study the effect of an amplification mechanism in a nonlinear vibration energy harvesting system where a ferromagnetic beam resonator is attached to the vibration source through an additional linear spring with a damper.The beam moves in the nonlinear double-well potential caused by interaction with two magnets.The piezoelectric patches with electrodes attached to the electrical circuit support mechanical energy transduction into electrical power.The results show that the additional spring can improve energy harvesting.By changing its stiffness,we observed various solutions.At the point of the optimal stiffness of the additional spring,the power output is amplified a few times depending on the excitation amplitude.

Networking Intelligent Pressure Sensor Using Digital Lock-in Amplification Technology

Introducing a System-on-Chip(SoC)microcontroller(C8051F350)into a ceramic pressure sensor has resulted in the design of a networking intelligent sensor.An improved algorithm for digital phase-sensitive detection is used to perform lock-in amplification of the sensor signal.The compensation for the sensor error is realized by the detection of the sensor’s supply voltage and working temperature.The system also has the function of short/open circuit fault detection and can communicate with other digital equipment through an RS-485 communication interface.In the design,full utilization of the SoC microcontroller’s internal resource results in the simple hardware structure.Experimental results show that the error of the sensor is less than 0.5% at range ratio 1∶10.Employing the microcontroller and using lock-in amplification algorithm are an effective method for achieving an intelligent sensor of slowly-varying physical quantities,thereby improving the measuring accuracy and performance.

Research Towards Terahertz Power Amplifiers in Silicon-Based Process

In view of the existing design challenges for Terahertz(THz)power amplifiers(PAs),the common design methods and the efforts of the State Key Laboratory of Millimeter Wave,Southeast University,China in the development of silicon-based THz PAs,mainly including silicon-based PAs with operating frequencies covering 100–300 GHz,are summarized in this paper.Particularly,we design an LC-balun-based two-stage differential cascode PA with a center frequency of 150 GHz and an output power of 14 dBm.Based on a Marchand balun,we report a 220 GHz three-stage differential cascode PA with a saturated output power of 9.5 dBm.To further increase the output power of THz PA,based on a four-way differential power combining technique,we report a 211–263 GHz dual-LC-tank-based broadband PA with a recorded 14.7 dBm Psat and 16.4 dB peak gain.All the above circuits are designed in a standard 130 nm silicon germanium(SiGe)BiCMOS process.

Vertical vibration control using nonlinear energy sink with inertial amplifier

To reduce additional mass, this work proposes a nonlinear energy sink(NES)with an inertial amplifier(NES-IA) to control the vertical vibration of the objects under harmonic and shock excitations. Moreover, this paper constructs pure nonlinear stiffness without neglecting the gravity effect of the oscillator. Both analytical and numerical methods are used to evaluate the performance of the NES-IA. The research findings indicate that even if the actual mass is 1% of the main oscillator, the NES-IA with proper inertia angles and mass distribution ratios can still effectively attenuate the steady-state and transient responses of the main oscillator. Nonlinear stiffness and damping also have important effects. Due to strongly nonlinear factors, the coupled system may exhibit higher branch responses under harmonic excitation. In shock excitation environment, the NES-IA with a large dynamic mass can trigger energy capture of both main resonance and high-frequency resonance. Furthermore, the comparison with the traditional NES also confirms the advantages of the NES-IA in overcoming mass dependence.

长波段半导体激光泵浦光纤激光器实现2 kW功率输出

半导体激光(LD)泵浦的高功率光纤激光器具有效率高、体积小、重量轻、稳定性好等优点,在工业加工等诸多领域都有着广泛的应用。为了提高泵浦光吸收率,传统光纤激光器常用915 nm和976 nm波段的LD作为激光的泵浦源。在该类LD泵浦的光纤激光器中,由于量子亏损和泵浦吸收系数相对较高,光纤激光器的热致模式不稳定(TMI)阈值相对较低。为了提高量子效率和潜在的TMI阈值,提出采用大于1010 nm波段的LD直接泵浦光纤激光器,产生高量子效率激光。搭建了振荡放大一体化的全光纤激光器,采用总泵浦功率为2.56 kW的1010 nm波段LD泵浦,首次获得输出功率2.05 kW、光束质量M^(2)约1.7的激光。后续将通过进一步增大泵浦功率、优化光纤特性以实现更高功率、更优光束质量的光纤激光输出。

患病异育银鲫中嗜冷黄杆菌的分离鉴定及组织病理学观察

为确定越冬期内江苏多地异育银鲫暴发性死亡的原因,本研究利用高通量测序比较了健康样品和患病样品的微生物群落多样性和结构组成的差异,分析了异育银鲫病害暴发过程中的细菌类型及特性。结果显示,在属水平上,患病样品中黄杆菌属丰度最高。在种水平上,患病样品中嗜冷黄杆菌的丰度最高,分别达到63.01%和61.31%,显著高于健康组的1.55%。根据微生物群落特征分析结果,从患病样品体表的病灶处分离出优势病原菌NJ01,通过细菌形态学、生理生化分析、16S rDNA序列比对确定NJ01菌株为嗜冷黄杆菌。人工感染NJ01菌株14 d后,1.7×10^(6)和1.7×10^(7) CFU/mL两组的死亡率达到100%,感染症状和自然发病症状一致。组织病理学观察发现,病鱼的肌细胞坏死,间质中充满了淋巴细胞;肝脏中细胞溶解坏死,细胞核消融;在脾脏中发现脾细胞散在坏死,伴随着充血的症状;肾小管上皮脱落,肾间质存在大量淋巴细胞。药物敏感实验结果显示,NJ01菌株对头孢西叮、头孢哌酮、庆大霉素和克拉霉素等敏感。研究表明,优势菌NJ01是致病菌,可通过扰乱机体正常的免疫和代谢功能导致疾病的发生。本研究首次报道了嗜冷黄杆菌在异育银鲫中的致病性,这将为大宗淡水鱼“越冬综合征”的药物防治及其致病机理研究提供参考依据。

医用3.0 T磁共振成像仪梯度系统故障三例

梯度系统是磁共振成像仪的重要组成部分,主要用于产生X轴,Y轴及Z轴三个方向的梯度信号,从而对磁共振信号进行空间编码,确定信号的空间位置。梯度系统功率高、散热量大,需要对梯度线圈及梯度放大器进行冷却。梯度系统及其冷却系统故障将导致图像质量下降甚至设备停机。本文总结了三例梯度系统故障,包括梯度线圈水冷系统故障、梯度放大器线路故障及梯度放大器散热风扇故障,包括三例故障的表现、探究了故障原因并给出故障排除方法,供同行参考,以期共同提升维修水平,提高设备使用率。

课程思政下运算放大器的混合式教学探索

在理工科核心课程中开展课程思政教育是当前教育发展的新模式。运算放大器是电路理论分析课程中的一个多端元件,对于帮助理解受控源有着非常重要的意义,同时在工程中有着多种实际应用。借助混合式教学这一模式,将思政教育贯彻到运算放大器的教学中,在传授知识的同时培养学生的爱国情怀和敬业精神。

红外探测器中一种电容式反馈跨阻放大器的设计

放大器电路对提高红外成像技术中红外探测器的读出精度,是至关重要的。针对电容式反馈跨阻放大器的设计进行了研究,提出了一种在反馈回路中用晶体管代替反馈电阻的新的拓扑结构。对于所提出的拓扑结构,提出并分析了与系统稳定性相关的诸如截止频率和衰减比等的总体频率响应和设计参数,从而获得高直流输入动态范围。此外,还讨论了在直流反馈回路中加入额外的电容以确保系统的稳定性。分析、仿真和实验结果的良好一致性验证了所提出的CF-TIA方案的有效性,而且所提出的电路设计在正常或低直流输入下的整体噪声性能方面相比于传统的CF-TIA方案更具优势。尽管本文中的电路采用分立元件实现,但提出的频率响应模型和稳定性分析适用于所有CF-TIA应用和CMOS芯片设计。