Effect of various parameters on working of all-optical Schmitt trigger

Schmitt triggers (ST) are well known and very widely used in the field of communications and signal processing techniques. It is robust, less sensitive to noise and is a building block in analog to digital converters. This work concentrates on all-optical Schmitt trigger for the purpose of using it in the field of optical modulation and signal processing. As the size of ring lasers is small these devices are best to use on a single integrated photonic chip. In this paper various dynamic effects of a binary Schmitt trigger is simulated and discussed. Control on various properties such as size of the ring, gain of SOA of a Schmitt trigger enables one to use it in developing all-optical devices.     

Multiple time scale chaos in a Schmitt trigger circuit

It is known that stray radio frequency signals can produce nonlinear effects that disrupt the operation of circuits, but the mechanisms by which this disruption occurs are not well known. In this paper, an emitter coupled Schmitt trigger circuit is driven with a high-frequency signal to look for disruptive effects. As the circuit makes a transition between mode locked states (period 2 and period 3, for example), there is a region of chaos in which the largest peak in the power spectrum is in between the mode-locked frequencies, and is not related to the driving frequency by an integer multiple. This chaos resembles the chaos seen during a period adding sequence, except that it contains frequencies ranging over many orders of magnitude, from the driving frequencies on the order of megahertz, down to a few hertz. It is found that only a one-transistor circuit is necessary to produce this extremely broadband chaos, and true quasiperiodicity is not seen in this circuit. The single-transistor circuit is then simulated to confirm the frequency conversion effects.     

555集成电路实验项目的创新设计

对555集成电路实验项目进行创新设计,使555集成电路的单稳态过程和多谐振荡过程同时出现,并且经过扩展又能实现施密特触发器的功能.Multisim仿真实验结果表明:三种过程的波形鲜明,实验线路实用性强,声光效果的应用又使实验变得趣味生动.     

脉冲激光器中实用升压与脉冲整形电路设计

基于稳压开关电源原理,采取斜坡补偿措施提高了Boost变换器的稳定性,从而获得一种升压型电源电路。针对脉冲激光器的特点,又提出两种正向施密特触发器,从而对输入的脉冲信号进行整形,以适应其中的电磁环境。对此升压脉冲整形联合电路进行的测试和实验表明,该电路具有输出电压可调、抗电磁干扰能力较强、紧凑可靠的优点,为脉冲激光照射器和测距仪提供了实用的电光调Q驱动脉冲输入级和供电电源。     

一种新型迈克尔逊干涉仪条纹计数器的设计

设计了一种简便的能自动适应不同背景光强的新型迈克尔逊干涉仪条纹计数器。利用光敏电阻将条纹的变化转化为电信号,同时检测出背景光,并利用减法器去掉背景,经施密特触发器整形后,送入单片机计数并显示。实验证明,本计数器原理简单,可以适应不同的背景光强,具有精确度高、操作简便可靠等优点。     

Marked signal improvement by stochastic resonance for aperiodic signals in the double-well system

On the basis of our mixed-signal simulations we report significant stochastic resonance induced input-output signal improvement in the double-well system for aperiodic input types. We used a pulse train with randomised pulse locations and a band-limited noise with low cut-off frequency as input signals, and applied a cross-spectral measure to quantify their noise content. We also supplemented our examinations with simulations in the Schmitt trigger to show that the signal improvement we obtained is not a result of a potential filtering effect due to the limited response time of the double-well dynamics.     

Resonance effects in the nonadiabatic nonlinear quantum dimer

In the presence of 1/f ^β noise, we investigate the logical stochastic resonance (LSR) in an asymmetric bistable model driven by various cycling combinations of two logic inputs. The probability of correct logic outputs is calculated according to true table of logic relationships. Two major results are presented. Firstly, it is shown that the LSR effect can be obtained by changing noise strength. Over entire range of noise variance, white noise can be considered to be better than 1/f noise or 1/f ² noise to obtain clean logic operation. At a smaller noise level, 1/f noise can realize higher output probability than white noise or 1/f ² noise. In the sense, 1/f noise can be considered to be better than white noise or 1/f ². On the other hand, the correct probability can evolves nonmonotonically as noise exponent β increases, and a kind of SR-like effect can be obtained as a result of β. At certain intermediate noise variance, the output probability is able to attain its minimum at β = 1. It is also shown that actually some finite β sometime can be better than β = 0 at small range of noise variance. The study might provide some potential complement to LSR effect in the presence of 1/f ^β noise.     

Noise-assisted multibit storage device

In this Letter we extend our investigations on noise-assisted storage devices through the experimental study of a loop composed of a single Schmitt trigger and an element that introduces a finite delay. We show that such a system allows the storage of several bits and does so more efficiently for an intermediate range of noise intensities. Finally, we study the probability of erroneous information retrieval as a function of elapsed time and show a way for predicting device performance independently of the number of stored bits.     

I/f noise in systems showing stochastic resonance

Stochastic resonator systems with input and/or output 1/f noise have been studied. Disordered magnets/dielectrics serve as examples for the case of output 1/f noise with white noise (thermal excitation) at the input of the resonators. Due to the fluctuation-dissipation theorem, the output noise is related to the out-of-phase component of the periodic peak of the output spectrum. Spin glasses and ferromagnets serve as interesting examples of coupled stochastic resonators. A proper coupling can lead to an extremely large signal-to-noise ratio. As a model system, a l/f-noise-driven Schmitt trigger has been investigated experimentally to study stochastic resonance with input 1/f noise. Under proper conditions, we have found several new nonlinearity effects, such as peaks at even harmonics, holes at even harmonics, and 1/f noise also in the output spectrum.     

Time-varying coupling-induced logical stochastic resonance in a periodically driven coupled bistable system

Coupling-induced logical stochastic resonance(LSR) can be observed in a noise-driven coupled bistable system where the behaviors of system can be interpreted consistently as a specific logic gate in an appropriate noise level. Here constant coupling is extended to time-varying coupling, and then we investigate the effect of time-varying coupling on LSR in a periodically driven coupled bistable system. When coupling intensity oscillates periodically with the same frequency with periodic force or relatively high frequency, the system successfully yields the desired logic output. When coupling intensity oscillates irregularly with phase disturbance, large phase disturbance reduces the area of optimal parameter region of coupling intensity and response speed of logic devices. Although the system behaves as a desired logic gate when the frequency of time-periodic coupling intensity is precisely equal to that of periodic force, the desired logic gate is not robust against tiny frequency difference and phase disturbance. Therefore, periodic coupling intensity with high frequency ratio is an optimal option to obtain a reliable and robust logic operation.     

施密特电路的触发过程及它在测量窄脉冲振幅时的准确度

本文研究了几种类型的施密特电路的触发过程。计算了这些电路的翻复速度并和实验加以比较。主要结果如下:(1)计算所得的翻复速度和实验结果是很符合的;(2)通用的直流耦合施密特电路的翻复速度是不快的;(3)带有二极管的施密特电路的翻复速度比上述电路要快得多;(4)采用交流耦合的施密特电路在翻复速度上可以比用直流耦合的施密特电路快三倍左右。因之联合采用(3)和(4)的电路可以大大地提高施密特电路的翻复速度。本文最后对上述几种施密特电路在测量窄脉冲振幅时的准确度作了讨论。     

Achieving high bit rate logical stochastic resonance in a bistable system by adjusting parameters

The phenomenon of logical stochastic resonance(LSR) in a nonlinear bistable system is demonstrated by numerical simulations and experiments. However, the bit rates of the logical signals are relatively low and not suitable for practical applications. First, we examine the responses of the bistable system with fixed parameters to different bit rate logic input signals, showing that an arbitrary high bit rate LSR in a bistable system cannot be achieved. Then, a normalized transform of the LSR bistable system is introduced through a kind of variable substitution. Based on the transform, it is found that LSR for arbitrary high bit rate logic signals in a bistable system can be achieved by adjusting the parameters of the system,setting bias value and amplifying the amplitudes of logic input signals and noise properly. Finally, the desired OR and AND logic outputs to high bit rate logic inputs in a bistable system are obtained by numerical simulations. The study might provide higher feasibility of LSR in practical engineering applications.     

双稳动力学系统中耦合效应对逻辑随机共振现象的增强作用

研究了电路耦合作用对逻辑随机共振现象以及逻辑门器件稳定性的影响．相对于单个的逻辑门电路,耦合的逻辑门器件可以在更宽的噪声范围内都保持逻辑运算的准确性,即耦合作用可以增强逻辑随机共振现象．此外,这种增强效应随着耦合体系尺度的增大而增大,但是当体系尺度达到一定程度时,这种增强作用达到一个稳定值．最后还考察了耦合强度的影响,发现随着耦合强度的增加,逻辑门器件可以保持逻辑运算准确性所对应的噪声区间非单调地改变,表现出一种共振的行为.     

闪光二号加速器气体主开关同步触发系统

 设计并调试了闪光二号加速器气体主开关同步触发系统。该系统主要由同步控制部分和高压脉冲形成部分构成。整个触发过程包括同步信号的引出、整形滤波、快速比较电路传输、前级脉冲形成、高压脉冲产生。通过对同步信号的整形处理,解决了发生器电流上的高频信号干扰问题;经过快速比较电路和前级脉冲后,选取了同步信号开始工作的时间点,并形成十几V的触发信号;高压脉冲形成部分主开关采用场畸变结合预电离的方式,该结构的气体开关时间响应为50 ns,抖动小于5 ns,满足使用要求。调试结果表明:该系统输出脉冲电压幅值100 kV,前沿小于10 ns,系统的工作时延440 ns,抖动13.5 ns;可通过增加电缆长度来控制触发信号到达气体开关的时刻,实现气体主开关与Marx发生器的延时同步工作。     

非高斯噪声驱动下一维双稳系统的逻辑操作

本文以成功率作为逻辑随机共振的测度, 主要研究了非高斯噪声激励下一维双稳系统的逻辑随机共振现象, 并用平均首次通过时间的方法对此现象的机理进行了解释. 研究结果表明: 只有在适当的噪声强度带或关联时间带上, 成功率才会达到共振峰值. 通过对系统参数进行优化, 提高了系统实现逻辑操作的可靠性. 关键词： 逻辑随机共振 一维双稳系统 非高斯噪声 平均首次通过时间     

晶体管施密特电路的开关过程

本文研究了施密特电路的开关过程。推导出了开关过程的具体解析表达式。根据这个表达式对两种常见的晶体管施密特电路进行了数值计算。最后用实验方法验证了计算结果。实验结果与计算值总的来说相当吻合。从这个研究中得到了挑选晶体管和电路的一些原则。计算结果可以作为设计施密特电路时估计开关速度的一个依据。     

基于光导开关的激光二极管触发三电极气体开关研究北大核心CSCD

为实现激光二极管对气体开关的触发,采用从主回路开关两侧取电的基于光导开关一体化激光二极管触发气体开关结构,并对基于光导开关一体化激光二极管触发三电极气体开关进行了初步实验,实现了激光二极管输出能量83μJ条件下40 kV/8 kA三电极气体开关的可靠触发,证明了技术可行性。但实验中的实测光导开关的工作寿命仅约数百次。     

Bifurcation and Entropy Analysis of a Chaotic Spike Oscillator Circuit Based on the S-Switch

This paper presents a model and experimental study of a chaotic spike oscillator based on a leaky integrate-and-fire (LIF) neuron, which has a switching element with an S-type current-voltage characteristic (S-switch). The oscillator generates spikes of the S-switch in the form of chaotic pulse position modulation driven by the feedback with rate coding instability of LIF neuron. The oscillator model with piecewise function of the S-switch has resistive feedback using a second order filter. The oscillator circuit is built on four operational amplifiers and two field-effect transistors (MOSFETs) that form an S-switch based on a Schmitt trigger, an active RC filter and a matching amplifier. We investigate the bifurcation diagrams of the model and the circuit and calculate the entropy of oscillations. For the analog circuit, the “regular oscillation-chaos” transition is analysed in a series of tests initiated by a step voltage in the matching amplifier. Entropy values are used to estimate the average time for the transition of oscillations to chaos and the degree of signal correlation of the transition mode of different tests. Study results can be applied in various reservoir computing applications, for example, in choosing and configuring the LogNNet network reservoir circuits.     

Unitary Application of the Quantum Error Correction Codes

For applying the perfect code to transmit quantum information over a noise channel, the standard protocol contains four steps: the encoding, the noise channel, the error-correction operation, and the decoding. In present work, we show that this protocol can be simplified. The error-correction operation is not necessary if the decoding is realized by the so-called complete unitary transformation. We also offer a quantum circuit, which can correct the arbitrary single-qubit errors.     

Bistable operation of multimode lasers containing saturable absorbers

Continous-wave operation of many longtudinal modes in a unidirectional ring cavity containing a laser medium and a saturable absorber is investigated. The phases of the modes are assumed to be randomly distributed. The system is described by a set of rate equations including noise terms from both media. The steady-state total intensity (as an average value) and the linewidth of the laser output are calculated for the region where bistable operation and hysteresis can occur. Moreover, the hysteresis cycles of individual modes are studied.