Investigations On The Dynamical Characteristics Of Pulse Packages In A Monolithically Integrated Amplified Feedback Laser

Optical feedback is one of the most common external disturbances for semiconductor lasers?SLs?.According to the magnitude relationship between the round-trip time in the external cavity and the relaxation oscillations period of laser.The optical feedback SLs system can be classified as long cavity regime optical feedback SLs?LCR-SLs?systems and short cavity regime optical feedback SLs?SCR-SLs?systems.The nonlinear dynamics of SCR-SLs systems are phase sensitivity due to short feedback cavity,even small change of feedback phase will make the nonlinear dynamics qualitative change.To built a discrete SCR-SLs system is more difficult than to bulit a discrete LCR-SLs because some components need to be placed in the feedback cavity to control the feedback parameters.As in this reason,the length of the external cavity is also difficult to reduce to centimeter-level level.In order to build a shorter SCR-SLs system,an implementation scheme based on photonic integrated technology is proposed,which integrates multiple functional sections on a same chip to constitute monolithic integrated amplified feedback laser?AFL?.The AFL possess some unique virtues such as shorter feedback cavity,more convenient to adjust feedback parameters,more stable and more suitable for commercial development.In recent years,domestic and foreign scholars have experimentally and theoretically explored the nonlinear dynamic characteristics of AFL.A recent experimentally study has been shown that the AFL can generate pulse packages?PPs?dynamic states,but the systematic research on the characteristics of PPs has not been reported.In this paper,we experimentally investigate the dynamic characteristics of PPs in a three-section monolithically integrated amplified feedback laser?AFL?composed of a distributed feedback?DFB?laser section,a phase?P?section,and an amplified feedback?A?section.By the aid of the power spectra and the self-correlation function curves on the time series outputs from the AFL,the influences of P section current I_P and A section current I_A on the repeated frequency of PPs ?_PP and the regularity of PPs are analyzed.The results show that,two modes are operated in the AFL when DFB section current IDFB is relatively large,meanwhile,through selecting suitable I_P and I_A,the AFL can work in PPs dynamic state.Under IDFB = 86.15 mA and I_P = 96.00 mA,,PPs state can be observed in two isolated ranges of I_A,With the increase of I_A,the repeated frequency of PPs ?_PP shows a monotonously decreasing trend in the low-current range of I_A,but in another range of higher I_A,?_PP decreases firstly,and then fluctuates within a tiny range.On the other hand,the characteristic regular feature of PPs is investigated by performing secondary maximum of the self-correlation???on the corresponding intensity time series,with the increase of I_A,the value of ? shows a gradually decrease trend in the low-current range of I_A,but in another range of relatively higher I_A,the value of ?increases firstly,after reaches a maximal value and then decreases.Under IDFB = 86.15 mA and I_A = 9.00 mA,,the characteristics of PPs outputs from AFL can be seriously effected by continuously varying I_P,through increasing I_P,?_PP shows a firstly decreasing and then increasing trend within the variation range of I_P required for AFL to work in PPs state,while the value of corresponding ? shows a firstly increasing and then decreasing trend.Finally,a mapping of PPs states is given in the parameter space of I_A and I_P by further observing and measuring the dynamics of AFL when I_P and I_A continuously varying.