Research On Real-time Extraction Of 1-bit Physical Random Number Based On Chaotic Laser

Random numbers are generally used in scientific research and daily life,such as simulation,radar ranging,communication quality detection and lottery gambling.Especially,random numbers are used to encrypt the information in the field of secure communications.According to “one-time pad” theory found by Shannon,the absolute security of the high-speed communication requires that ultrafast reliable random number generation is generated in real-time.Using complex algorithms can generate pseudorandom numbers,but they can be predicted due to their periodicity.On the other hand,random numbers based on physical stochastic phenomena can provide reliable random numbers.However,their generation rates are at the level of Mbit/s typically,limited by the bandwidth of traditional physical sources(such as electronic noise,frequency jitter of oscillator).In recent years,high-speed physical random number generation based on chaotic laser has made breakthrough progresses.Common methods of extractingrandom numbers are to sample and quantize the chaotic signal in electronic domain with a 1-bit or multi-bit analog to digital converters(ADCs)triggered by the RF clock and then post-process the raw binary sequences into random numbers.However,the large jitter of the RF clock severely restricts the speed of ADC.Moreover,the existence of the subsequent post-processing processes put a huge challenge how to keep the synchronization among all the devices(e.g.,XOR gates,memory buffers,parallel serial converters)using a RF clock.Thus,to our knowledge,the fastest real-time speed of the reported physical random number generator is less than 5 Gbit/s.Supported by the special fund for basic research on scientific instruments of the national natural science foundation of China(Grant No.61227016),we investigate a novel method for real-time physical random number generation utilizing chaotic laser pulses in this thesis.Through sampling the chaotic laser in all-optical domain using a mode-locked pulse laser,chaotic laser pulse sequences can be obtained.Then,real-time physical random numbers are obtained directly by self-delay comparing the chaotic pulse sequences with no need of RF clocks and any post-processing.A study of "real-time 1-bit extraction of physical random numbers based on chaotic laser" is mainly completed the following work:1.By introducing the applications of random numbers in scientific research and daily life,we illustrate the important significance of random number generations;We also introduce the present situation of physical random number,and summarizes the common schemes for physical random numbers generation;Then we have a comparison on the random number extraction schemes based on chaotic laser.2.A proof-of-principle experiment is carried out,where an optical feedback chaotic semiconductor laser is employed as the entropy source.Experiment results show that the real-time random number sequences at rates of up to 7Gbit/s can be achieved.The real-time speed is mainly limited by the bandwidth of the applied chaotic signal.If the chaotic laser with a higher bandwidth is adopted,the real-time generation rate can be further enhanced.3.On the basis of the aforementioned random number extraction scheme based on chaotic laser proposed,we design and make a photo-electric quantizer prototype.This prototype is used to quantify the signal after sampling by adopting the method of delay comparison and pulse modulation.The output signal of this prototype is optical signal,the output type is a return to zero code,and working band is 1550 nm.4.We summarize all the works in this thesis and discuss the possible development direction of the future.