Research On The Stochastic Resonance Theory In Weak Optical Signal Enhancement

Detection of weak signal buried in noise is inevitable in the field of engineering applications.Inhibiting or filtering noise to improve the signal to noise ratio of system output is the main method of weak signal detection so that weak signal is extracted from strong noise.However,this method has many disadvantages.To make matter worse,when the noise intensity larger than the signal intensity,it is difficult to detect signal using the methods of time-domain averaging or linear filtering.Researching the detection of weak signal has important theoretical and practical significance to satisfy the needs of modern science and technology.However,the discovery of stochastic resonance overturned people’s original idea that noise is considered to be harmful factors.In some specific nonlinear systems,when it reaches the matching state among the signal,noise and nonlinear systems,the signal and noise will produce a synergistic effect,so that the noise energy is transferred to the orderly weak signal,thereby the output signal to noise ratio of the systems are improved.In this paper,the theory and its application of the stochastic resonance in weak optical signal enhancement are investigated.The main contents and achievements of this paper are as follows:1.The research background and the significance of weak optical signal enhancement have been introduced,and the concept and current situation of stochastic resonance were given.The history,status and development of stochastic resonance based optical bistability and the potential application of weak optical signal detection were introduced.2.The theory of the stochastic resonance,including the basic principle and typical theoretical models at present were summarized,and the evaluation methods of ability that stochastic resonance systems extracting the weak optical signal were also analyzed.3.The optical transmission characteristics of the semiconductor optical amplifier are researched.Starting with the rate equation of carrier concentration in active medium,the evolution of optical power,phase and gain in active medium are derived and then the relationship between the input and output light intensity is obtained.Optical bistability is realized by numerical simulation.4.The bistable output characteristics in SOA and the influence of system parameters,such as cavity length,mirror reflectivity,initial phase detuning and optical antiguidance factor on bistable transmission is investigated.The stochastic resonance is realized at a suitable bistable region by optimizing the system parameters to extract weak pulse signal buried in noise.Its ability for processing and reconstructing the weak optical pulse signal is analyzed under different noise intensities,which is evaluated by the cross-correlation gain.