Theorertical Study Of All-optical Random Number Generation Based On Mode Hopping

Random number plays crucial role in the field of information security.It is used as a key to encrypt information.As long as the key is not cracked,the security of information can be maintained.According to the "One-time Pad"theory proposed by Shannon,in order to achieve unconditional secure communication,it is necessary to generate a large number of true random numbers with the rate that meets the transmission rate of modern communication.At the same time,the trend of miniaturization of modern communication equipments have placed stringent requirements on the volume and power consumption of RNGs.Utilizing physical random process as entropy source,ture random number can be generated,which can fundamentally ensure the security of communication.However,the existing true random number products are limited by the entropy source bandwidth,and the bit rate is only in Mb/s,which can not meet the high-speed transmission of modern communication systems.In recent years,with the continuous further research of laser technology,many schemes are proposed to extract high-speed physical random number by using the stochastic dynamics in lasers.However,most of reported schemes contain four parts:laser sources,sampling,quantizing and post-processing modules.This results in requiring a large number of discrete photonic and electronic components.We propose a method for fast all-optical random number generation based on the laser mode hopping,and theoretically study the feasibility of obtaining correlate random number based on this method.All the signal processing is done in the optical domain without any photo-electronic conversion and post-processing.This method provide a new idea for photonic integrated PRNGs.Specifically,the following researches have been done for the problems involved in this paper:1.To validate the feasibility of this method,we perform a theoretical simulation using the solitary VCSEL.Through periodically restarting a VCSEL operating in the bistable state,a random number stream can be generated due to the spontaneous emission noise.Numerical results demonstrate that at least 2.5 Gb/s random number streams can be continuously obtained with verified randomness.2.We theoretically analyze two critical factors which determine the uniformity and high generation rate of random numbers.Results show that the spontaneous emission noise is the critical to ensure the uniformity of the generated random numbers.Moreover,the generation rate is mainly limited by the relaxation oscillation time from non-lasing to a stable lasing mode.3.We propose a random bit synchronization scheme in unidirectionally coupled VCSELs.The master VCSEL outputs random bits,whilst the slave VCSEL free-running.Numerical results show that master-slave lasers can achieve high quality synchronization(cross-correlation C>0.9)in the range of-60 GHz<?v<50 GHz and kinj>4%without considering the parameter mismatch.When the parameter mismatch is considered,the birefringence parameter yp and the injection current ? have the greatest influence on the synchronization quality.4.We also propose a unidirectionally coupled synchronization scheme in which both master and slave VCSELs output random bits.Numerical results show that the master-slave lasers can achieve high quality synchronization(C>0.9)in the range of Av>0 GHz without considering parameter mismatch.When?v<0 GHz,the master-slave lasers have anti-correlated synchronization(C<-0.8)under kinj<20%.