Investigation On Acquiring Intermittent Chaos Based On Monolithic Integrated Semiconductor

Chaos has attracted considerable attention due to its extensive applications in chaotic radar,secure communication,random-bit generation,etc.In general,semiconductor lasers subject to external disturbances such as optical injection,optical feedback and photoelectric feedback can generate chaos outputs.Among these chaos generation methods,the optical feedback system has become a focus due to its relatively simple scheme and easy to acquire high-dimension chaos.Especially,under suitable conditions,the optical feedback system can generate both continuous chaos and intermittent chaos with random alternation between chaos state and other states.Previous optical feedback systems to generate chaos are almost composed of discrete components,which greatly hinder the application progress of such chaotic system.After using photonic integration technology to integrate the main components of the system on a single chip,the size and cost of the system can be greatly reduced and the system stability can be also improved.As a result,the monolithic integrated semiconductor laser(MISL)can be produced,which paves the way to produce the integrated chaotic generation devices.At present,the related reports of chaos generation and its application based on MISL mainly focus on the case of continuous chaos,while the investigation on intermittent chaos is relatively scarce.In this paper,a three-section MISL,which is composed of a 220 ?m distributed feedback(DFB)laser section,a 240 ?m phase(P)section and a 320 ?m amplifier(A)section,is used in our experiment,and the nonlinear dynamical states,especially intermittent chaos of such system under different parameters are experimentally investigated.The results show that two types of intermittent chaos can be observed.When the current of DFB laser section IDFB = 2.07 Ith,the current of phase section IP = 9.6 mA,and the current of amplifier section IA is adjusted from 13.5 m A to 14.5 mA,the laser output behaves as a stochastic alternation between stable state and chaos state,and the average dwell time of the stable state becomes shorter with increasing IA,which is named as type I intermittent chaos(TC1).For the case of IDFB = 2.2 Ith and IP =10.8 mA,rich nonlinear dynamic behaviors such as period-one,period-two,intermittent chaos,and chaos can be observed under different IA.When increasing IA from 15.0 mA to 15.4 mA,laser output behaves as a stochastic alternation between period-two state and chaos state,which is named as type II intermittent chaos(TC2).Further increasing IA from 16.2 mA to 16.8 mA,TC1 can also be observed.Moreover,the mapping of the dynamical states in the parameter space of IP and IA under IDFB = 2.2 Ith has also been given and TC1 region is relatively larger than TC2 region.In addition,when IDFB=3.4 Ith,IA=34.5 mA,IP is adjusting from 8.5 mA to 9.4 mA,type ? intermittent chaos(TC3)can be observed and the average dwell time of stable state is becoming longer with increasing IP.