Malica Tushar, Bouchez Guillaume, Wolfersberger Delphine, Sciamanna Marc
Opt Lett. 2020 Feb 15;45(4):819-822. doi: 10.1364/OL.383557.
An 852 nm semiconductor laser is experimentally subjected to phase-conjugate time-delayed feedback achieved through four-wave mixing in a photorefractive ($ {{\rm BaTiO}_{3}} $BaTiO) crystal. Permutation entropy (PE) is used to uncover distinctive temporal signatures corresponding to the sub-harmonics of the round-trip time and the relaxation oscillations. Complex spatiotemporal outputs with high PE mostly upwards of $ \sim 0.85 $∼0.85 and chaos bandwidth (BW) up to $ \sim 31;{\rm GHz} $∼31GHz are observed over feedback strengths up to 7%. The low-feedback region counterintuitively exhibits spatiotemporal reorganization, and the variation in the chaos BW is restricted within a small range of 1.66 GHz, marking the transition between the dynamics driven by the relaxation oscillations and the external cavity round-trip time. The immunity of the chaos BW and the complexity against such spatiotemporal reorganization show promise as an excellent candidate for secure communication applications.
对一个852纳米的半导体激光器进行了实验，通过光折变（$ {{\rm BaTiO}_{3}} $BaTiO）晶体中的四波混频实现相位共轭延时反馈。排列熵（PE）用于揭示与往返时间的次谐波和弛豫振荡相对应的独特时间特征。在高达7%的反馈强度下，观察到具有高PE（大多高于$ \sim 0.85 $∼0.85）和高达$ \sim 31;{\rm GHz} $∼31GHz的混沌带宽（BW）的复杂时空输出。低反馈区域出人意料地表现出时空重组，混沌BW的变化限制在1.66 GHz的小范围内，标志着由弛豫振荡驱动的动力学与外腔往返时间之间的转变。混沌BW的抗扰性和针对这种时空重组的复杂性显示出有望成为安全通信应用的优秀候选者。
