Research On Application Of Optical Chaos Based On VCSELs

Chaos research in laser physics,especially the optical chaos in semiconductor laser systems,has been well developed and is still developing rapidly.Optical chaos is expected to produce fruitful results not only for the fundamental research of chaos but also for applications as dynamic engineering.For instance,various forms of chaotic dynamics have been applied in semiconductor lasers,such as in conventional edge-emitting semiconductor laser(EEL)and new vertical-cavity surface-emitting laser(VCSEL).Chaotic dynamics plays an important role in these lasers,even for their solitary oscillations,and control of the dynamics is currently an important issue for practical application.As for the application of optical chaos,significant advance has been made in the field of chaotic optical secure communication.Several methods of data encryption into the chaotic carrier and its decryption have been introduced for secure data transmission and communication based on chaos synchronization in semiconductor laser systems.Besides,many chaotic secure communications using existing public optical communications links have been tested,and satisfying results have been obtained.Compared to EEL,VCSEL is very attractive because it may provide a number of advantages.Notably,submilliampere threshold current,low threshold voltage,high output power,low power consumption,and high power conversion efficiency have been reported.The operating wavelength range of VCSEL now extends from 670 nm to 1550 nm.These achievements have led VCSEL to emerge as potential lightwave sources for a variety of applications,including high speed optical communication and optical interconnect.Since parallel lightwave systems based on optical chaos are urgently needed to meet the rapid increase of information transmission and communication,the importance of VCSEL is currently increasing.Therefore,this paper has proposed two structures of communication systems based on optical chaos generated by multiple VCSELs.In order to investigate the application value of optical chaos,messages and images have been introduced in the optical communication,respectively.Firstly,a novel long-distance multi-channel bidirectional chaos communication system over multiple paths based on two synchronized VCSELs has been proposed and studied theoretically.These two responding VCSELs(R-VCSELs)are capable of outputting similar chaotic signals served as chaotic carrier in two linear polarization modes with identical signal injection from a driving VCSEL(D-VCSEL),which is subject to optical feedback and optical injection,simultaneously.Through numerical simulations,the high quality chaos synchronization between the two R-VCSELs has been obtained.Besides,the effects of varied qualities of chaos synchronization on communication performances in single mode fiber(SMF)channels have been investigated by regulating different internal parameters mismatch after adopting chaos masking(CM)technique.The result shows that,with the decreases of maximum cross correlation coefficient(Max-C)between the two R-VCSELs,the bit error rate(BER)of decoded message increases.Based on high quality synchronization,when the dispersion compensating fiber(DCF)links were introduced,4n messages of 10 Gbit/s can transmit in 180 km SMF channels over n coupling paths,bidirectionally and simultaneously.Thorough tests have been carried out with detailed analysis,demonstrating the feasibility of long-distance,multi-channel,bidirectional chaos communication based on VCSELs.Secondly,a novel symmetric image encryption-then-transmission system based on optical chaos using VCSELs has been proposed.With identical chaotic injection from a master VCSEL(M-VCSEL),two slave VCSELs(S-VCSEL1 and S-VCSEL2)are capable of outputting similar chaotic signals served as chaotic carrier to transmit image.Meanwhile,the chaotic signal of S-VCSEL1 can be used to generate the key of the encryption scheme.After employing the three-dimensional(3D)cat map and chaotic logistic map,not only the positions of image pixels were shuffled,but also the relationship between the cipher-image and the plain-image was confused simultaneously.Thus,the system could resist the common attacks such as statistical attack,differential attack,and brute force attack.Through numerical simulations,the high quality chaos synchronization between the two S-VCSELs has been obtained.When CM technique was adopted,the image encrypted by the proposed encryption scheme can be successfully transmitted and decrypted in SMF channel from S-VCSEL1 to S-VCSEL2 with a BER of less than 6.18 × 10-19.Exhaustive tests about security analysis have been carried out,demonstrating the potential feasibility and high security of the proposed image encryption-then-transmission system based on optical chaos.In the application of optical chaos based on VCSELs,the system of message transmission,especially the image encryption-then-transmission system,has very special significance since there are a few researches about it to the best of my knowledge.We suggest that this paper will be of interest not only to researchers in the area of cryptography,but also to whom working in nonlinear science and technology.