光学双稳态在光纤传感器的应用

光强调制型光纤传感器，已得到了广泛的应用，它的测量灵敏度，精度和稳定性，主要取决于光源输出功率的稳定性，传统的办法是采用引入参考光路，利用光电补偿方法，来减小光源波动造成的影响，我们提出采用光学双稳装置来稳定光源输出功率，并将它用於折射率调制型光纤传感器测量液体浓度的实验中，本文详细报导了该装置的原理，内容和测量结果，并指出进一步研究方向。     

Integrated bistable optical device using mach-zehnder interferometric optical waveguide

An integrated mirrorless bistable optical device based on the Mach-Zehnder interferometric optical switch has been proposed and demonstrated experimentally using a Ti: LiNbO3 waveguide. The resulting device is capable of combining more than two of them to realise multifunctional optical devices such as optical multivibrators.     

混合型光学双稳态的光脉冲放大

利用一个氦氖-铌酸锂混合型光学双稳态装置实现了固定光偏置和脉冲光偏置两种方式下的光信号放大,光信号增益分别为15和20～95.理论计算和实验结果基本相符.     

Nonbiased optical bistable device in an impedance-mismatchedasymmetric Fabry-Perot structure

It is shown that nonbiased optical bistability in an extremely shallow quantum well symmetric self-electro-optic effect device can be significantly improved by using an impedance-mismatched asymmetric Fabry-Perot scheme. The device in a simple layout shows nonbiased bistability width, ΔR, contrast, and V^op of ~53%, 17%, 3.7:1, and 0.9 V, respectively     

Charge-induced self-feedback optical bistable device: switchingtime and spatial resolution

We report extensive experimental and theoretical studies on the properties of an optical bistable device called the charge-induced self-feedback device (CSFD) which is a variation of a self electro-optic effect device (SEED). In the mechanism, a novelty: of the CSFD consists of the feedback due to field-screening, resulting in independent switchings of optical beams focused at different spots on the CSFD without the help of pixellated structures. We experimentally demonstrate independent switchings without pixellation. In addition, a spatial resolution of the CSFD on such a device operation is found to be limited by an in-plane spreading of photoexcited carriers enhanced by a lateral electric-field induced by photoexcitation. Also, it is experimentally demonstrated that shortening carrier escape times leads to an improvement on the spatial resolution in terms of the suppression of the in-plane carrier spreading. Furthermore, an investigation on dynamics of the photoexcited carriers in the device reveals that the switching time of the CSPD is on the order of nanosecond, limited mainly by the hole escape time     

Simplified optical fibre end-cleave angle measurement device

A modified method of fibre end-cleave angle measurement is described and compared with alternative techniques. The device has no precision parts and has a resolution of better than 0.25 degrees of end angle.     

High finesse, thin active layer, multiquantum well optical bistable device

Optical bistability was observed in a multiquantum well microcavity, with a 500 W/cm/sup 2/ intensity threshold and a 10:1 contrast. The device design enhances the cavity finesse (here up to 250), by increasing the number of layers in the Bragg mirror stacks and simultaneously reducing the active layer thickness (here 3 lambda /2, i.e. 360 nm).<>     

Operation of an all-optical bistable device dependent upon incidentand transmitted optical power

The authors describe the optically bistable operation of an all-optical nonlinear Fabry-Perot etalon (NLFP) in which the power-dependent cavity phase shift has a contribution dependent on the power incident on the cavity. When the contributions have the same parity, the optically-bistable behavior is essentially the same as that seen in the now standard bistable NLFP (counterclockwise hysteresis in transmission). For opposite parity there is a range of relative strengths for which bistable operation cannot be obtained, but, outside of that range, bistable behavior having clockwise hysteresis in transmission is possible. This latter bistable behavior is demonstrated, with the NLFP being a GaAlAs laser diode amplifier driven by a similar diode laser. Low-frequency modulation of the laser power by direct variation of the laser drive current produced a small shift in laser wavelength proportional to the laser power, providing the cavity phase shift term proportional to the incident power, while the nonlinear refractive index of the NLFP provided the phase shift proportional to the transmitted power     

一种连续状态反馈方法控制混合光学双稳系统混沌

本文设计了一种连续状态反馈(CSF)方法控制非线性混沌系统,并将此方法应用到混合光学双稳(MOB)系统混沌的控制上,验证其有效性。文中给出了CSF控制方法的构建依据、控制原理以及控制参数的选择技巧并使用计算机数值模拟了MOB系统混沌被控制后的动力学行为。数值分析结果表明,适当地调整控制参数不仅可以实现原混沌系统内部的非稳定周期轨道稳定化,还可以将原混沌系统控制到其它的目标周期轨道上去。此种控制方法稳定性好,控制速度快,且可以方便灵活地获得1p、2p、3p…2mp×3np(m,n为整数)等多种稳定的周期轨道。同时,CSF方法对低周期和高周期轨道的控制都很有效。     

Optimum order of angle diversity with equal-gain combining receivers for broad-band indoor optical wireless communications

Angle diversity is an effective technique to compensate for multipath temporal dispersion in a wireless infrared environment. Diversity is accomplished by using a multibranch receiver capable of resolving multipath. The goal of this paper is to illustrate the effect that the increasing diversity order of a receiver has on the performance of a link in a multispot-diffusing configuration with equal-gain combining outage probability based on probability of bit error is adopted as a performance measure. It is shown that there is an optimal number of branches, which minimizes outage probability. Increasing diversity order beyond this optimal number degrades the performance and increases the receiver complexity, cost, and susceptibility to any shadowing effects.     

Fabrication of low-stress low-stiffness leveraged cantilever beam for bistable mechanism

This paper presents the fabrication and application of a leveraged cantilever beam with low-stress and low-stiffness. This cantilever beam is overhanged with two free ends and suspended in air by the supporting torsion flexures fixed at its middle. The teeterboard-typed cantilever features a low-stiffness with 1.63 N/m, and a low-stress with ±6.27 MPa. The cantilever beam was prepared by a laminated photoresist sacrificial layer process (LPSLP), that is, a multilayered photoresist film for supporting the suspended cantilever beams. In this work, two main problems related to microfabrication process were discussed. One is the control of residual stress in permalloy cantilever with varying the contents of additive saccharin to minimize the deformation of the free end of the beams. The other is an improved wet release method to avoid the adhesion or stiction of the all metal microstructures. The proposed leveraged cantilever beam has a potential application on the bistable switching mechanism in single-pole-double-through (SPDT) latching relay fields. Switching between two stable states of the microbeam mechanism was successfully validated with WYKO NT1100 optical profiling system.     

光学双稳态（非线性方程）的一种新数值求解方法

光学双稳态的调制函数和反馈函数构成一组非线性方程，通常用迭代法求解它们，迭代是否收敛取决于初始解选择的恰当与否，为了顺利求解，我们找到了一种新的数值求解非线性方程组的方法，本文还指出可以利用数值求解方法，来寻找新的双稳装置和研究它的性能。这实际是用计算机作光学双稳装置的模拟研究。     

Optimum stochastic inspection policies for a system with safety device

In this paper we discuss an optimal stochastic inspection policy for systems that consist of a safefy related module which is supervised by a second module. The life time distributions of the modules are arbitrary. A failure of the safety relevant module is determined by the supervising module provided the latter is functioning. Function of the supervising module can be determined only upon inspection. An inspection returns the system into a state as good as new. The system fails if the safety relevant module fails undetected. The optimal inspection policy is searched among stochastic strategies, i.e. strategies that are able to consider different inspection times with various probabilities.     

Optimum ordering policies for an equipment with a sensing device

This paper conerns the optimum ordering policy for a single equipment with a sensing device attached, where operational conditions of the equipment are monitored by the attached sensing device continuously. Both the equipment and the sensing device are subject to random failures. It is shown that there exists under certain conditions a finite and unique optimum ordering policy maximizing the cost effectiveness which is used as a criterion for optimality. Numerical examples are presented for illustration.     

A new bistable laser diode configuration for all optical switching

A new bistable laser diode configuration for all optical switching has been suggested and its equivalent circuit model is developed. For switching the device to the high state (set) a TE mode optical pulse is required, which is the oscillating mode of the laser, whereas a TM mode pulse is used to bring the output to a low state (reset). But the wavelength of the set and reset pulses are the same as that of the lasing wavelength of the device. The static and dynamic characteristics are studied by simulating the equivalent circuit model using the circuit simulation program PSPICE. It is found that as the carrier lifetime τ_a of the absorption section increases, the width of the optical pulse required for reset increases nonlinearly. The rise and fall times are found to be 0.15 and 0.16 ns, respectively, for a τ _a, of 3 ns     

Optimum networks for simultaneous multiple beam antennas

The design of passive microwave circuits for the formation of simultaneous multiple beams with arbitrary but specified shapes is considered. The maximum possible efficiency is derived from energy conservation and is determined from a Hermitian matrix whose elements are the correlation coefficients between all beam pairs. The eigenfunctions of the correlation matrix are the basis of a synthesis procedure for a practical network that will achieve the maximum efficiency. Several practical examples are given where unavoidable losses are typically 1 dB or more     

Optimum beamformers for monopulse angle estimation usingoverlapping subarrays

We here derive the optimum sum and difference beamformers for monopulse target localization using a linear array. The beamformers are constructed, treating as superelements two overlapping subarrays. Removing the common factor associated with the superelement pattern from the angle error function leads to a closed-form target angle estimator independent of any adaptive nulling performed. Performance analysis of the angle estimator is conducted, and a procedure is developed to construct the beamformers, which achieve the minimum estimation variance under Gaussian noise. It is shown that the optimum angle estimator using the maximum overlapping subarrays is efficient for a moderately high signal-noise ratio (SNR) and a small off-boresight angle. The proposed method can be easily modified to incorporate interference cancellation     

Optimum load device for DMOS integrated circuits

Depletion-mode load devices can be integrated with DMOS transistors without any extra diffusions or implantation processing steps by judicious choice of the substrate crystal orientation and resistivity. For low voltage operation, <1,1,1> crystal orientation should be used. The <1,1,1> crystal orientation also yields a higher transconductance for the DMOS transistor than the <1,0,0> orientation. The geometry of the load device and the DMOS transistor can be made ratioless to conserve area. Self-aligned gates, hitherto considered incompatible with DMOS transistors, have been incorporated in the structure. The experimental DMOS invertors, using a conservative design, have achieved 4-ns propagation delay, 1.3-V operation and 2-pJ propagation delay-power dissipation product.     

A new adaptive amplifier for biased electron beam induced current applications

A novel amplifier for Electron Beam Induced Current (EBIC) mapping is presented which enables sample polarization and which provides at the same time good characteristics in terms of sensitivity, input bandwidth and noise-immunity. The proposed circuitry includes an adaptive self-compensation of the DC level due to the leakage currents.     

一种激光方位角的判定方法

阐述了一种利用光学窗口阵列接收激光脉冲状态判断激光方位角的方法。这种方法避免了复杂的电路和复杂的计算。此外,还阐述了利用光学窗口光强比和增加光学窗口数目提高系统精度的两种方法,并比较了在不同光学窗口数目情形下,光学窗口的透镜参数及可以达到的精度。通过这种方法,可以用较少的光学窗口,得到较高的角分辨率。