Noise induced order : An experimental approach with optical bistable systems

研究了噪声诱导有序的一种典型现象-随机共振。随机共振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。鉴于其通过加入噪声来控制信噪比的能力，有望应用于信号处理，特别是光信号处理。1.对正弦输入信号进行了混合光调制系统中的随机共振实验。实验结果表明，噪声相关时间越短，信噪比峰值越大，共振宽度越窄，产生峰值信噪比的噪声强度越小。2.对二进制输入信号的随机共振进行了数值模拟。结果发现，输出信号具有信息增益，并且具有小相关时间的噪声有利于SR和增益。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视性，为信号处理提供了有力的工具。3.研究了一种新型的电势涨落SR，其中势垒是变化的。比较了电位涨落引起的SR与噪声输入引起的标准型SR的基本特性。4.利用半导体激光器和法布里-珀罗谐振腔，在两个反射镜之间插入染料溶液（ZnPC）或半导体晶体（ZnTe），构建了将超分辨率应用于光信号处理的全光反射系统。该系统可以实现全光同步辐射的快速工作。

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.