High-speed Random Number Generation And Research Based On Wideband Laser Chaotic Entropy Source

Random numbers are widely used in Monte Carlo simulation,spread spectrum communication,radar ranging,and information security.In particular,in the field of confidential communications,generating safe and reliable random numbers is related to many aspects such as national defense security,financial stability,business secrets,and personal privacy.In recent years,traditional physical random number generators mostly use resistance thermal noise,oscillator jitter and chaotic circuits as physical entropy sources,but their rate are limited by the bandwidth of these entropy sources,which is far from the current high-speed communication rate.The chaotic laser is suitable for high-speed physical random numbers generation due to its high bandwidth,random amplitude variation,and easy integration.However,because the relaxation oscillation of the semiconductor laser limits the bandwidth and flatness of the power spectrum,the resonance of the external cavity causes the chaotic signal to have a significant delay characteristic at the period of the external cavity,and the amplitude oscillation of the external cavity semiconductor laser is uneven,which greatly restricts the entropy source rate of physical random numbers and deteriorates the randomness and reliability of random numbers.In response to the above problems,we proposed three broadband complex laser chaos entropy source generation schemes based on delayed coherent phase modulation,multi-frequency sinusoidal phase modulation and random phase modulation feedback,respectively.The numerical results demonstrate that the effective bandwidths of the chaotic signals increase from 10.5GHz to 81.4GHz and 48.6GHz in the proposed two schemes based on delay coherent phase modulation and multi-frequency sinusoidal phase modulation,respectively.Besides,the spectrum flatness of the chaos entropy source is significantly improved.Compared with the original chaotic signal,the time delay signature(TDS)of the signal is completely suppressed.The influences of parameters such as feedback strength,delay time,dispersion coefficient of single-mode fiber and phase modulation depth on the bandwidth and complexity of chaotic signal are further investigated,and the system parameters were optimized.Finally,a laser chaos entropy source scheme based on random phase modulation feedback is experimentally verified.It is observed that the waveforms of output chaos are denser,the amplitude probability distribution is symmetrical like a Gaussian distribution,and the radio frequency spectrum is significantly broadened and flatter.Moreover,the bandwidth is increased from 8.8GHz to 22.4GHz and TDS is completely suppressed.Based on the above three broadband complex laser chaotic entropy sources,the output light generated by them is converted into electrical signals by a photo detector,it is triggered by clocks with sampling rates of 250GS/s,100GS/s,and 100GS/s respectively.8Bit ADC quantization combined with delayed XOR processing retains the least significant 3 bits,3 bits,and 4 bits,respectively,and finally obtains high-speed random numbers with equivalent rates of 750Gbit/s,300 Gbits,and 400Gbit/s,respectively.The randomness and uniformity of the generated random numbers were further studied,and all of them passed the NIST test.