Study On Microscopic Statistical Properties Of Chaotic Laser Based On Highly Sensitive Optoeletronic Counter

With the increasing requirement of transmission rate and reliability of information in modern society,secure communication is becoming increasingly important in the field of network communication.The properties of chaotic laser satisfy the basic requirement of information security and cryptography.Chaotic laser has attracted widespread attention,being applied to high-speed remote chaotic secure communications,rapid physical random numbers technique.High-speed remote secure key distribution with chaotic laser has attracted intense attention.The quantum statistic properties and noise fluctuation of chaotic field have great effects on secure key distribution.The research on quantum statistical properties of chaotic field not only contributes to realizing profoundly the physical nature of light field,but also plays an important role in the implementation of secure communication.The quantum statistical properties of the field can be exploited via single-photon detection.Meanwhile,it providesa good paltform for the application of secure key distribution based on chaotic field and revealing the nonclassicality of the field.1.In this paper,photon number distribution and second-order degree of coherence of a chaotic laser are analyzed and measured based on HBT scheme.The chaotic laser is composed of a distributed feedback laser diode with optical feedback in fiber external cavity configuration.It is concluded that chaotic laser can be obviously distinguished from other light fields(such as thermal light,coherent light and single photon)through theoretical analysis of second order degree of coherence.2.The second order degree of coherence of the pulse chaotic light field with different pulse width and coherence time have been theoretically analyzed.The second-order degree of coherence of pulse chaotic light field,thermal pulse light field,pulse coherent light have been compared under the conditions of different duty ratio.3.The bandwith of the chaotic laser that we obtain experimentally is 6.7GHz.The photon number distribution of chaotic laser is fitted by Gaussian random distribution,Possionian distribution and Bose-Einstein distribution.With an increase of the mean photon number,the photon number distribution changes from Bose-Einstein distribution to Poissonian distribution and always agrees with Gaussian random distribution well.The second-order coherence g(2)(0)drops gradually from 2 to 1.By changing the bias current(I=1.0Ith-2.0Ith)and feedback strength(0-10%),we compare and illustrate different chaoticdynamics and g(2)(0).From Low Frequency Fluctuation(LFF)to Coherence Collapse(CC),the chaotic laser shows bunching effect and fully chaotic field can be obtained at the broadest bandwith.Furthermore,the physical explanation for sub-chaotic or weakening of bunching effect is provided.