摘要:
实验研究了由分布反馈激光器区(DFB区)、相位控制区(P区)以及放大反馈区(A区)所构成的三段式单片集成放大反馈激光器(AFL)所产生的脉冲包络(PPs)的动力学特征,并分析了P区电流IP和A区电流IA对PPs的重复频率νPP以及包络规则性的影响。研究结果表明： DFB区电流IDFB相对较大时, AFL 存在两个模式,此时通过选取合适的IP和IA可使AFL工作在PPs动力学状态；对于一给定的IP , IA在两个分离区域内可使AFL呈现PPs状态。随着IA的增加,在IA相对较小的区域, AFL输出PPs的重复频率νPP以及表征PPs规则性的时间序列自相关函数的次最大值σ均呈现单调下降趋势。而在IA相对较大的区域,νPP呈现出先减小然后小幅波动的变化趋势,而σ则总体呈现先增加后减小的趋势；对于一给定的IA , IP的变化也会对AFL输出PPs的特性产生显著影响,在AFL呈现PPs状态所要求的IP的变化范围内,随着IP的增加,νPP呈现出先减小后增大而σ则呈现先增加后减小的变化趋势。通过观测IA, IP 连续变化时AFL的动力学特性,确定了AFL呈现PPs在IA和IP构成的参量空间的分布图谱。
Abstract:
Under suitable external perturbation such as optical feedback, optical injection or optoelectronic feedback, semi-conductor lasers can be driven to realize diverse dynamic outputs including period-one, period-two, multi-period, pulse packages (PPs), chaos, etc., which have potential applications in optical secure communications, microwave photonics, lidar, high speed random signal generation, etc.. For the PPs dynamics, most of previous relevant investigations are usually based on a system composed of discrete elements. In this work, we experimentally investigate the PP dynamical characteristics 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. For the AFL, the sections P and A act as a compounded feedback cavity in which the feedback phase and strength can be varied by adjusting the current in section P (IP) and the current in section A (IA), respectively. Via the power spectrum and self-correlation function curve of the time series output from the AFL, the influences of IP and IA on repeated frequency (νPP) and regularity of PPs are analyzed in detail. The results indicate that, for the section DFB, whose current (IDFB) is biased at a relatively large level, the AFL can realize two-mode oscillation. After further choosing appropriate IP and IA, the AFL can behave as the dynamical state of PPs. Under IDFB = 86.15 mA and IP = 96.00 mA, through varying IA in a range of 6.50–10.50 mA, there exist two separated regions for IA to make the AFL operate at PPs. For the region with relatively small value of IA, both νPP and the secondary maximum (σ) of self-correlation curve characterizing the regularity of PPs monotonically decrease with the increase of IA. However, for the region with relatively large value of IA, with the increase of IA, νPP first decreases and then fluctuates in a tiny range, but σ first increases, and further reaches an extreme value, and then decreases. Under IDFB =86.15 mA and IA =9.00 mA, the output characteristics of PPs are significantly affected by IP. With IP increasing from 90.5 mA to 96.5 mA, νPP first decreases, and then increases after reaching a minimal value, meanwhile σ shows an approximately opposite variation trend. Finally, for IDFB = 86.15 mA, the mapping of PPs in the parameter space of IP and IA is given and the evolution regularities of PPs are also presented.
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