Research On Physical Random Number Generator Using Integrated Silicon Photonics Devices

Random numbers play a vital role in scientific research and engineering applications.At present,random numbers have been widely used in many fields such as Monte Carlo simulation,wireless communication,gaming,artificial neural networks,and radar ranging.Amang them,the true random numbers(often called as physical random numbers)which is generated from the random nature of the physical entropy source have higher security performance.Therefore,the research on the physical random number has been a topic of constant duration.However,the rate of physical random numbers from conventional physical entropy sources,such as oscillator jitter,thermal noise sampling,etc.,is usually limited by the bandwidth of entropy source(usually on the order of Mbits)and cannot meet the requirement of modern communication.In recent years,laser chaos has become an ideal entropy source for constructing a safe,reliable,high-speed physical random number generator,due to its high bandwidth and high complexity.It has attracted the intensive attention of researchers all over the world.Nonetheless,most current solutions for physical random numbers using laser chaos are based on III-V material devices(such as InGaAsP),which is generally bulky,complex,and lacking in practicality.Therefore,we proposed a new scheme in this paper for physical random bit(PRB)sequence using silicon-based photonic microcavity as entropy sources.The feasibility of this scheme is verified experimentally and PRB sequences of Gbits rate are generated.The main content is following:1.the theoretical physical random bit scheme is studied using the optical chaos of silicon-based photonic devices.By adjusting the external excitation parameters,the silicon-based photonic microcavity is induced to generate high-intensity local light field,mechanical oscillation and significant two-photon absorption effect,thereby obtaining the original chaotic output.The chaos is processed by a parallel combination method and converted into electrical signal with photodetector.Next,the signal is digitized as bit sequences by an 8-bit analog-to-digital converter(ADC),and finally passed the NIST and Diehard test using the self-delay exclusive-OR(XOR)and least significant bit(LSB)operation.In this thesis,we theoretically investigated the optical chaos characteristics of silicon-based photonic devices and the post-processing of physical random bit.The results show that the original chaos can be post-processed to increase the randomness and uniformity of the signal amplitude distribution,and then become qualified entropy source for physical random bit generation.We quantitatively analyze the feasibility of generating physical random bits by subsequent processing from multiple randomness,and finally receive qualified physical random bit sequence with 200 Mbits rate.2.A PRB generator is investigated experimentally based on silicon photonic devices for Gbits rate.In the experiment,we obtained the chaotic output from silicon-based photonics micro-cavities,and the offline processing is carried out to obtain PRB sequence with Gbits rate.This thesis focuses on the difference of two subsequent processing methods,parallel combination and discrete time derivative,on the generation of PRB sequence.The experimental results show that parallel combination method requires a linear combination of at least 8 entropy source signals and retain the 4-least significant bit(LSB)to obtain qualified PRB sequence,and discrete time derivative method requires high-order differential processing above 5th order and retains the 5-LSB to obtain PRB sequence passed all test items of the NIST standard test.