Multi-channel Physical Random Number Generation Based On Two Orthogonally Mutually Coupled 1550 Nm Vertical-cavity Surface-emitting Lasers

Physical random number,which is non-reproducibility and non-periodicity,has attracted much attention due to its potential applications in various fields such as secure communication,statistical analysis,numerical simulation and so on.Semiconductor lasers under external disturbances can generate high-bandwidth and large-amplitude laser chaotic signals,which is used as a source of physical entropy to obtain random numbers.And compared to the traditional physics entropy source,further developments have been made in the generation of random numbers.Currently scholars have done a lot of research on the generation of random number generator based on laser chaos,most of the schemes are based on distributed feedback semiconductor laser(DFB),which can only generate single-channel physical random number.However under appropriate parameters,a vertical cavity surface emitting laser(VCSEL)can output two orthogonal polarization components simultaneously,and each polarization component can then be used as an entropy source to generate a physical random number.It is possible to develop a multichannel physical random number generator generation scheme.Therefore,chaotic entropy sources of VCSEL may be suitable for multi-channel random number generation.In this paper,a scheme for achieving multi-channel physical random number is proposed.Also,the influence of the coupled parameters on the performances of the randomness of final bit sequences are investigated.For such a scheme,two orthogonally mutually coupled VCSELs are used to supply four-channel chaotic signals with a comparable output power and weak time-delay signature(TDS).The four-channel chaotic signals,which are taken as chaotic entropy,are quantized by 8-bit analog-to-digital converters(ADCs)with 20 GHz,and then the m least significant bits(m-LSBs)postprocessing methods are adopted for generating final four-channel random bit sequences.Firstly,based on the spin-flip mode of VCSELs,the influence of coupling strength and frequency detuning on the dynamics of two orthogonal mutually coupled 1550 nm VCSELs are analyzed.Next,the optimized parameter regions for generating four-channel chaotic signals with comparable output power and weak TDS are preliminarily determined.For a given optimized value of coupling strength and different frequency detuning within the optimized parameter regions,the generated four-channel chaotic signals are taken as the entropy sources for obtaining final bit sequence by the quantization of 8-bit ADC and m-LSBs post-processing.Finally,the randomness of four final bit sequences are tested by NIST SP 800-22 statistical test suite,and the regions of preferred coupled parameters for simultaneously generating four-channel random numbers are determined.