石英光纤中自组纳米光栅偏振调控的矢量光场产生研究

The capability of precisely manipulating the interaction between optical vector fields and matter is a fundamental and cutting-edge research topic in currently optical fields. Silica fiber not only acts as the important carrier of optical communication and nonlinear optical signal process, but also supports the generation and stable propagation of radially polarized (RP) vector beam, which has flexible control of optical amplitude, phase and polarization distribution. RP vector beams have been demonstrated as a powerful tool to investigate the interaction between optical fields and matter and enrich many interesting phenomena and new physical effects. Recently new research on generating ultra-fast optical vector beam in silica fiber provides a novel approach to multi-dimensionally control optical fields. The research contents include: 1) investigate the formation mechanics of sub-wavelength nanograting directly written by femtosecond pulses and establish the growth dynamics of self-assembled microstructures in doped silica material; 2) based on femtosecond radiation on the rotating fibers, three-dimensional nanograting structures with different polarization guiding are constructed inside the silica few-mode fiber; 3) through the interaction between the fiber evanescent field with subwavelength nanogratings, study the key scientific physics of generation, evolution and polarization control of eigen-vector optical fields in silica fiber; 4) explore new methods of generating all-fiber ultra-fast vector optical pulse and key applications by fabricating the fiber polarization-selection and mode coupler, which is implemented in mode-locking fiber lasers. The expected results will promote the ability of controlling vector optical fields, which have widely application prospects in the scientific fields, such as special fibers, optical field control and optical micro-manipulation.

精密控制矢量光场与物质相互作用过程是当今光学领域的基础前沿类课题。石英光纤不仅作为光通信和非线性光信号处理的重要载体，而且能够支持柱矢量光场产生和稳定传输。柱矢量光场聚焦下有灵活可控的振幅、相位以及偏振态分布，已经成为重要的光学手段，丰富了光与物质相互作用的新物理和新效应。近年来在光纤中研究新型超快矢量光场产生，为光场多维调控提供了新思路。本项目拟研究石英光纤中飞秒激光直写亚波长纳米光栅的形成机理，建立纳米光栅在掺杂石英光纤基质中自组织生长的动力学过程；基于光纤旋转的飞秒直写技术，构建具有不同偏振导光的三维纳米光栅结构；通过光纤消逝场与亚波长光栅作用，研究本征矢量光场在光纤中产生、演化机制和偏振调控的核心科学问题；基于光纤偏振选择模式耦合器制备及在锁模光纤激光器中的应用，探索全光纤超快矢量光场脉冲产生。预期成果将提升新型光场调控创新能力，在特种光纤、光场调控、光学微加工等领域有广阔前景。

精密控制矢量光场与物质相互作用过程是当今光学领域的基础前沿类课题。石英光纤不仅作为光通信和非线性光信号处理的重要载体，而且能够支持柱矢量光场产生和稳定传输。本项目研究了石英光纤中飞秒激光直写亚波长纳米光栅的形成机理，采用飞秒直写技术在光纤包层中植入纳米光栅，在石英光纤纤芯内直写纳米光栅阵列，采用提拉法即扫描方向平行于波矢方向，激光相对于光纤轴向向上提拉，同时采用激光偏振方向按阵列排布需要进行旋转，构建了具有不同偏振导光的三维纳米光栅结构。通过光纤消逝场与亚波长光栅作用，研究了本征矢量光场在光纤中产生、演化机制和偏振调控。并基于单模光纤-阶跃少模光纤耦合器和声致光纤光栅器件，提出了径向偏振、角向偏振和的光OAM旋涡的产生方法，对光纤锁模激光器中的涡旋光模式切换动力学过程进行研究；同时制备了可见光波段的全光纤模式选择耦合器，基于光纤涡旋光场的环状光束作为受激发射损耗光束，提出全光纤环形光束光源方案，并将这一特性运用到受激发射损耗显微成像光源技术的研究。