Noise induced order : An experimental approach with optical bistable systems

随机共振是一种典型的噪声诱导有序现象。SR是一种通过在输入相干信号中加入随机噪声来提高输出信噪比的协同现象。尽管它的外观很奇怪，但它发生在各种系统中。由于可以通过添加噪声来控制信噪比，因此有望应用于信号处理，特别是光信号处理。在混合光双稳系统中对正弦输入信号进行了SR实验。实验结果表明，噪声相关时间越短，峰值信噪比越大，共振宽度越窄，产生峰值信噪比的噪声强度越小。通过数值模拟研究了二进制输入信号的SR。结果表明，输出信号具有一定的信息增益，且相关时间较小的噪声有利于SR和增益的提高。模拟了图像数据的SR行为。仿真结果表明，该系统可以提高图像的可见性，是一种强有力的信号处理工具。研究了一种新的势垒变化的势涨落磁阻。比较了基于电位波动的磁振振荡器与基于噪声输入的标准型磁振振荡器的基本特性。在我们的实验中发现了几个新特征。构建了将SR应用于光信号处理的全光双稳系统，该系统使用二极管激光器和法布里-珀罗谐振器，在两个反射镜之间使用染料溶液（ZnPC）或半导体晶体（ZnTe）。该系统可以实现全光SR的快速运算。

We studied stochastic resonance (SR) as a typical phenomenon of noise induced order. SR is a cooperative phenomenon that the output signal-to-noise ratio (SNR) is enhanced by adding random noise to the input coherent signal. In spite of its strange appearance, it occurs in various systems. In view of the ability of controlling SNR by adding noise, it is expected to be applied to signal processing, especially to optical signal processing.1.SR experiments in hybrid optical bistable systems were performed for a sinusoidal input signal. The experimental results show that, with smaller noise correlation time, the peak value of the SNR is larger, the width of the resonance is narrower, and the noise intensity which gives the peak SNR is smaller.2.SR for a binary input signal was studied by numerical simulations. It was found that the output signal has a gain of information, and that the noise with a small correlation time is favorable for SR and for the gain. The behavior of SR for image data was simulated. The simulation results show that this system can improve the visibility of images and can be a powerful tool for signal processing.3.A new type of SR by potential fluctuation, where the potential barrier is varied, was studied. The fundamental characteristic of the SR by potential fluctuation was compared with that of the standard type of SR by noise input. Several new features were found in our experiment.4.All-optical bistable systems to apply SR to optical signal processing were constructed, where a diode laser and Fabry-Perot resonator with a dye solution (ZnPC) or semiconductor crystal (ZnTe) between two mirrors were used. This system can give a fast operation of all-optical SR.