Dispersion tuning via geometry induced resonances – a novel concept for scaling output powers in coherent supercontinuum generation

由于其在生物光子学或时间分辨光谱学等一系列领域的巨大潜力，利用非线性光学效应产生光是当前光子学中一个备受关注的研究领域。超连续谱产生(SCG)与初始窄带光脉冲的光谱展宽有关，已被认为是产生具有所需性质的光的最重要机制之一。一种非常有效的宽带和定制SCG方法依赖于高阶时间孤子分裂成它们的基本孤子，这导致多余的能量发射到线性色散波。这一过程与相位匹配过程有关，而相位匹配过程主要取决于所使用的光波导的色散。本项目的总体目标是了解几何诱导的光谱共振对混合光纤光波导中SCG过程的影响，定义一种新的色散管理方案，最终目的是解锁新的孤子动力学并放大SCG中的能量。概念上的新想法是利用特定光纤设计的微结构元件诱导的强烈光谱共振来大规模修改色散(特别是群速度色散(GVD))，从而改变孤子动力学和色散波相位匹配过程。包含所有相关效应的非线性脉冲传输模拟将揭示孤子，特别是孤子裂变过程是如何在一个数量级变化的GVD环境中在一个狭窄的谱区间内演化的。我们将制作各种结构共振接近激光波长的实芯和空芯光纤，从实验上研究结构共振的影响。初步模拟表明，强大的结构共振允许在大幅增加芯径时保持主色散特性(特别是零色散波长)--这在Kagome或毛细管波导中是不可能实现的。因此，几何诱导共振通过使用超大的纤芯直径，有可能在SCG中放大功率水平，从而避免光纤输入处的损伤或气体电离，这是目前SCG功率缩放方案中的主要限制因素。该项目的研究成果将对科学和应用的各个领域产生影响，如量子计量学、非线性物理或光谱学，并不局限于光纤或特定的光谱领域。可以设想用于理想地寻址电磁频谱的期望部分的新型超宽带光源。

The generation of light using nonlinear optical effects represents one highly addressed research area within current photonics due to its great potential in a series of areas including biophotonics or time-resolved spectroscopy. Supercontinuum generation (SCG), which is associated with the spectral broadening of an initially narrowband optical pulse has been identified as one of the most important mechanisms to generate light with desired properties. One very efficient way for broadband and tailored SCG relies on the fission of higher-order temporal solitons into their fundamental counterparts, which leads to the emission of excess energy into linear dispersive waves. This process is associated with a phase-matching process, which dominantly depends on the chromatic dispersion of the waveguide used.The overall aim of this project is to understand the influence of geometry-induced spectral resonances on the SCG process in hybrid fiber waveguides, defining a novel dispersion management scheme with the ultimate aim to unlock new soliton dynamics and to scale up energies in SCG. The conceptually new idea is to use strong spectral resonances, induced by microstructured elements of the specific fiber design used, to massively modify chromatic dispersion (in particular group velocity dispersion (GVD)), thus altering soliton dynamics and dispersive wave phase-matching processes. Nonlinear pulse propagation simulations that include all relevant effects will reveal how solitons and in particular the soliton fission process evolve in an environment of an orders of magnitude changing GVD in a narrow spectral interval. Various types of solid and hollow core fibers that have structural resonances close to the laser wavelength are to be implemented to investigate the impact of structural resonances experimentally. Preliminary simulations suggest that strong structural resonances allow maintaining the main dispersion characteristics (in particular the zero dispersion wavelength) when substantially increasing core diameters – a situation that is not achievable in Kagome or capillary waveguides. Therefore, geometry-induced resonances have the potential for scaling up power level in SCG by using exceptionally large core diameters, thus avoiding damage or gas ionization at the fiber input, which represents the main limiting factor in current schemes for SCG power scaling.The research output of this project will have impact in various areas of science and application such as quantum metrology, nonlinear physics or spectroscopy and is not restricted to fibers or a specific spectral domain. New types of ultrabroadband light sources for desirably addressing desired parts of the electromagnetic spectrum can be envisioned.