| With the rapid development of semiconductor integration technology,people have been able to fabricate photon integrated devices in the quantum level,and have carried out detailed research in related fields.As one of the integrated light sources,quantum dot micro-pillar laser has potential applications in secure communication.Compared with traditional semiconductor laser,this kind of light source has some advantages such as laser threshold,light field characteristics and so on.At the same time,quantum dot micro-pillar laser is a good experimental platform for cavity quantum electrodynamics because of its small size and significant interaction between light and matter.Strong coupling effect,high quality single-photon source and partial injection-locked nonlinear dynamics have been observed in the quantum dot micro-pillar laser system.Due to the special dynamic phenomenon of quantum dot micro-pillar laser,which is different from ordinary semiconductor laser,nonlinear dynamic process and chaos have been produced by constructing external optical feedback disturbance in quantum dot micro-pillar laser.At the same time,people have also studied the quantum properties of chaos and quantum random numbers.Chaotic lasers have been widely used in the fields of generation and evaluation of high speed physical random number,optical time-domain reflectometer,chaotic secure communication,chaotic lidar and photon integration,and so on.Optical feedback is one of the typical methods to generate chaotic light.However,due to the delay of external cavity,the chaotic light signal will have the characteristics of external cavity period or time delay signature,which limits the application of chaotic light in random bits generation.On the other hand,the bandwidth of chaotic light determines the transmission rate of chaotic secure communication,so the suppression of time delay signature and bandwidth enhancement of chaotic light become the hotspot of extensive research at home and abroad.At present,the time-delay signature of chaotic light is suppressed and the bandwidth is enhanced by the methods of mixing filter,double optical feedback,double-channel filter optical feedback,phase modulation double-path feedback and single-end feedback mutual coupling.Meanwhile,the TDS and effetive bandwidth of three kinds of chaotic light system are analyzed and compared.However,these systems are based on standard semi-conductor laser,which are relatively large in size,not suitable to future integration miniaturization,and the chaotic light of output is a single-mode non-orthogonal mode.For quantum dot micro-pillar lasers,the basic cavity mode split into two orthogonal linear polarization components due to the degeneracy of the mode energy of the output mode.Therefore,under the disturbance of optical feedback,quantum dot micro-pillar laser can output orthogonal double mode chaotic light field,and because of its micron size,quantum dot micro-pillar laser is very suitable for the future development of miniaturization and integration.In view of the above contents,the specific research work and results of this paper are as follows:1.Based on the semi-classical four-variable rate equation of the optical feedback quantum dot micro-pillar laser,the theoretical model of the optical feedback quantum dot micro-pillar laser is constructed.The input and output characteristics of optical feedback quantum dot micro-pillar laser are theoretically simulated,and under the condition of low pump current,the strong and weak mode will not bifurcate.With the increase of the pump current,the strong and weak mode begin to bifurcate.And with the increase of the pump current,the bifurcation becomes more and more obvious.The size of bifurcation can represent the mode competition between strong and weak mode,and the output power difference between strong and weak mode can represent the mode competition between strong and weak mode.2.The influence of external control parameters(optical feedback intensity and pump current)on the chaotic light field of strong and weak mode is analyzed systematically.The time series and first-order photon auto-correlation of the chaotic light field of strong and weak mode are analyzed,as well as the delay characteristic peak value and effective bandwidth of the chaotic light field.The results show that with the increase of the feedback intensity,the points of the image of the output chaotic light field of strong and weak mode become more and more dense,and the complexity of chaos becomes higher and higher.When the mode competition between the strong and weak mode is strong,the output power difference of the strong and weak mode first decreases and then increases with the increase of the feedback intensity of the strong and weak modes.With the increase of the feedback intensity of the strong and weak modes,the effective bandwidth of the chaotic light field first increases,then decreases,and then increases.When the pump current is 13?A and the feedback intensities of strong mode and weak mode are 4ns-1and 3ns-1respectively,the effective bandwidth of the chaotic light of the strong mode and weak mode increase to the first peak value of 8.91 GHz and 8.49 GHz,respectively.With the increase of the feedback intensity,the time delay signature of the two-mode chaotic laser increases first and decreases,and then increases.When the pump current is 13?A,the feedback intensities of the strong mode and weak mode are 16ns-1and 14ns-1,the time delay signatures of the coherence-collapse chaotic light of strong mode and weak mode are 0.083 and 0.092 respectively,and the corresponding effective bandwidths are 11.31GHz and 11.02GHz,respectively.3.The influence of the internal parameters of quantum dot micro-pillar laser on the strong and weak mode chaotic light field is systematically analyzed.With the increase of the optical gain coefficient of the strong and weak mode,when the pump current is 12?A,the output power of strong mode increases from 302nw to 875nw,and that of weak mode increases from420nw to 980nw.With the increase of the spontaneous emission lifetime,the output power of strong mode increases from 371nw to 1798nw,and that of weak mode increases from 403nw to 1301nw.With the increase of the spontaneous emission lifetime,when the pump current is13?A,the delay characteristic peak of strong mode output chaotic light field changes from0.1353 to 0.2960,and that of weak mode changes from 0.1128 to 0.2467.Similarly,with the increase of the optical gain coefficient of the strong and weak modes,the delay characteristic peak of output chaotic light field of strong mode changes from 0.1910 to 0.4145,and that of weak mode changes from 0.2178 to 0.4448.With the increase of linewidth enhancement factor,when the pump current is 13?A,the output power of the strong mode decreases from1096nw to 798nw,and that of the weak mode decreases from 139.2nw to 79.8nw.With the increase of linewidth enhancement factor,when the pump current is 13?A,the delay characteristic peak of output chaotic light field of strong mode decreases from 0.54 to 0.26,and that of weak mode decreases from 0.49 to 0.262.With the increase of active quantum dots,when the pump current is 13?A,the output power of strong mode increases from 493.3nw to1336.5nw,and that of weak mode increases from 165.8nw to 404.02nw. |
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