Investigation On Two-channel Physical Random Number Generation Based On A Vertical-cavity Surface-emitting Laser With Double Optical Feedback

Random number, because of its unpredictable, not emersion characteristics, has widely application in the field of science and technology, such as, secure communicat io n, stochastic modeling and monte carlo method, and so on. Based on access to the class of gaussian distribution entropy source signal from the sthermal noise, the oscillator frequency jitter and chaotic circuit in the field of traditional electronic circuit, can get random number sequence. But restricted by electronic bandwidth bottlenecks and other factors, the rate of the random number generator usual y in Mbits/s level, can not meet the requirements of modern information communication. In recent years, the studies that laser chaos based on semiconductor laser(SL) under the external disturbance as a source of entropy to get random numbers have made great progress, but most research results are based on the chaotic entropy source of edge-emitting semiconductor lasers(EESLs). Because EESLs generally only have a polarization mode blaster, so only a single channel can generate random number. Vertical-cavity surface-emitting laser(VCSELs) because of its low threshold current, the light direction is vertical with the substrate surface, the beam is circular, small divergence angle and a series of unique advantages, and under the condition of appropriate external disturbance of two orthogonal polarization components can be output chaotic signal, use it as a source of entropy, chaos is expected to get dual random number sequence.Thus, after taking two orthogonally polarized modes in a vertical-cavity surfaceemitting laser(VCSEL) with double optical feedback as two source of entropy, We propose an acquisition method of two-channel physical random number(PRN) sequences. Based on the spin flip model(SFM), firstly, the chaotic output of two polarizat io n components from vertical cavity surface emitting lasers(VCSELs) under differe nt feedback intensity was studied, and then the follow-up bit sequence generation method was focused on, finally, the random performance of the final bit sequence obtained of two polarized components under different feedback intensity was numerical analysised in theory. The results show that, under the appropriate feedback parameters, both two polarized modes in a VCSELs may be driven into chaotic oscillation simultaneously, and with the increase of two feedback intensity, time delay characteristics peak and the bandwidth of the chaotic signal overall showed a gradual trend of increase. With two lines of chaotic signal from vertical cavity surface emitting lasers(VCSELs) output as the entropy of the source. Next, the two entropy sources are sampled by an 8-bit analog-todigital converter(ADC). As a result, bit-order-reversed method, bitwise exclusive- O R(XOR) operation and m least significant bits(m-LSBs) selection are further used in the post-processing of bit sequences to obtain two final bit sequences. Finally, the randomness of two final bit sequences is tested by NIST SP 800-22 statistical test suite, and the regions of the feedback strengths which lead to perfect test results are primarily determined. And under the optimal feedback intensity, two-channel high-speed random number sequence was won success in theory.