复合腔光纤激光器中异种脉冲叠加态的产生及相干调控研究

Multipulsing is an inherent property in mode-locked fiber lasers. Generally, the optical manipulation between heterogeneous pulse patterns is hard to realize for they are incoherent, which leads to that they have not practical values. The project aims at the study of coherent superposition states composed of heterogeneous pulse patterns with coherent manipulations for opening up their application prospects in the field of optical information processing. The project will adopt an experiment approach for studying the generation and coherent manipulation of heterogeneous pulse patterns generated from a fiber laser with a hybrid cavity configuration, assisted by numerical calculations and theoretical analysis. The research works contain: (1) A theoretical model of a fiber laser with a hybrid cavity configuration is proposed for mastering the rules of the effects of the key physical parameters on the generation of superposition states such as coupling efficiency of a subcavity, diffusivity of doped ions in the gain fibers, filtering parameters, etc. (2) The self-started heterogeneous pulses are experimentally achieved from the laser. The coherent interactions between them are realized through locking their phases, which results in that the subcavity pulse pattern can coherently manipulate the main pulse pattern. The discussions are carried out for the effects of fixed and periodically evolving temporal gaps and phases of heterogeneous pulses on the coherent manipulation. (3) The project also focuses on studying transient procedures of coherent manipulation between heterogeneous pulses in order to summary the rules of coherent manipulation. The project will have an important academic significance for deepening the full understanding of the dynamics of heterogeneous pulse patterns evolving in fiber lasers, as well as achieve potential applications in fields of pulse coding, optical delay and controlling based on coherent manipulation between heterogeneous pulse patterns.

多脉冲现象是锁模光纤激光器的本征属性。通常，由异种脉冲格式构成的叠加态是非相干的，无法实现有效的光场调控，难有实用价值。为了实现异种脉冲间的相干作用，开辟异种脉冲叠加态在光信息处理领域的应用前景，本项目拟对复合腔光纤激光器中异种脉冲相干叠加态的产生及其相干调控动力学特性开展以下理论与实验工作：(1)建立复合腔光纤激光器的理论模型，研究子腔耦合效率、增益掺杂离子扩散度、滤波调制系数等关键物理参数对异种脉冲叠加态产生的影响；(2)实验获得自启动异种脉冲格式，通过相位锁定来实现异种脉冲间相干作用，达到子腔脉冲对主腔脉冲的相干光场调控目的，讨论时域间隔与相位关系对异种脉冲间相干光场调控的影响；(3)研究异种脉冲间相干调控的瞬态动力学过程，总结相干调控规律。本项目的开展不仅能全面认识异种脉冲相干叠加态的动力学特性，而且其研究成果在脉冲纠缠编码、光延时、光控光等领域有着重要的科学价值和应用前景。

多脉冲现象是锁模光纤激光器的本征属性。锁模光纤激光器产生各种奇特的脉冲格式是当今激光技术的重要前沿学术课题。对特殊脉冲格式及其叠加态的特性研究，将促进现代先进激光技术在微纳加工、精密测量与传感等领域的新应用具有重要意义。本项目对复合腔光纤激光器中异种脉冲格式构成的特殊脉冲叠加态的产生及其光场调控动力学特性开展以下理论与实验工作：. (1)建立复合腔光纤激光器的理论模型，研究非线性系数与滤波调制系数等关键物理参数对特殊脉冲格式产生的影响。获得了异种脉冲格式的叠加态。. (2)设计了在低启动阈值条件下产生高能量脉冲的复合腔光纤激光器和能对时域脉冲动态切片的脉冲激光器。. (3)实验观察到了特殊的异种脉冲格式叠加态h脉冲及h脉冲雨。提出了一种解释h脉冲产生的物理新机制，即激光腔内的周期弱滤波函数产生不同脉冲格式，通过交叉相位调制实现的一种轮廓为字母“h”形状的束缚脉冲单元。h脉冲前沿尖峰源于周期滤波函数的主透射峰，后延方波成分源于周期滤波函数的第一级透射率峰，雨脉冲源于周期滤波函数的高级透射率峰。h脉冲与脉冲雨是异种脉冲格式叠加态的特殊形式。h脉冲与h脉冲雨可以通过腔内偏振状态的调节实现两个状态的切换。. (4)使用两套相干的束缚态孤子脉冲格式作为泵浦源，在高非线性光纤中首次实现了消除残余泵浦峰的新型超连续谱。这是相干异种脉冲格式的重要工程应用。以往孤子脉冲、束缚态孤子簇等脉冲格式作为泵浦源产生的超连续谱或多或少地存在残留的泵浦峰。我们采用新型的异种脉冲格式相干泵浦方案，解决了超连续谱中不能实现完全能量转换的传统难题，在激光光源应用上具有重要的应用前景。. 本项目的开展不仅能全面认识异种脉冲叠加态的动力学特性及其光场调控，而且其研究成果在精密制造、微纳激光技术等领域有着重要的科学价值和应用前景。