Study On The Technology Of Weak Terahertz Signal Restoration Based On Graphene Bistable System In Fabry-perot Cavity Via Stochastic Resonance

In the past three decades,the theories,models and applications of the stochastic resonance have attracted great attention among the researchers.The related research work has developed vigorously.At present,the researches about the theories and applications of the stochastic resonance have extensively involved various subjects and fields of study,such as physics,chemistry,biology,communication,machinery,electronics,seismology and neural network,etc.The appearance of the stochastic resonance phenomenon makes people realize that the noise is not necessarily harmful all the time.In the particular nonlinear system,the noise can be used to amplify weak signals.The stochastic resonance theory gives a new approach to the detection and enhancement of the weak signals.The unique advantages of the stochastic resonance offer a wide space for its applications in the area of signal processing.In this paper,the theoretical methods of weak light signals enhancement have been studied,and the weak terahertz nanosecond pulse signals have been extracted from strong noisy background.The main results of this paper are summarized as follows:1.The research background and significance of weak light signal enhancement and detection technology was discussed.The traditional weak light signal detection technologies and the development status of the stochastic resonance were introduced.2.The theoretical methods of the stochastic resonance based on classical bistability theory were analyzed.The establishing process of the theoretical model and the mechanisms of the stochastic resonance generation were researched.Then,the process of extracting weak signals from the strong noise background based on stochastic resonance was analogue simulated,by taking the example of a delayed bistable model.3.The theory of the bistability in the Fabry-Perot cavity with grapheme was discussed,included the nonlinear response theory of graphene in terahertz and the bistable system structure.Besides,the influence of the various system parameters on bistable property of the system was analyzed,such as,signal light frequency,Fermi energy,transmission rate of the mirror,cavity length and relaxation time.It provided the foundation of the weak terahertz signal restoration via stochastic resonance.4.The stochastic resonance theory based on the bistability in the Fabry-Perot cavity with graphene was proposed.The nanosecond pulse signals under the strong noise background were extracted in this system.The system was evaluated by the cross-correlation coefficient.The results showed that the output signals can be improved considerably within the larger noise intensity range in this system.The system shows the great ability to improve the output signal-to-noise ratio.