标题： 多模光纤折射率剖面的定制用于参量边带的空间和光谱整形 显示英文标题

标题： Refractive index profile tailoring of multimode optical fibers for the spatial and spectral shaping of parametric sidebands

摘要： 我们通过定制其线性折射率剖面，引入了在多模光纤中对非线性参量边带进行空间和光谱控制的概念。 在所有情况下，泵浦经历克尔自清洁，导致接近基模的钟形剖面。 由于泵浦自成像产生的光栅引起的准相位匹配，几何参量不稳定性导致了光束自清洁在宽频带边带阵列中的频率多路复用。 我们的实验表明，在渐变折射率光纤的折射率剖面中引入高斯凹陷，可以显著改变光谱边带的空间内容，使其进入高阶模式。 这是由于基模和高阶模式之间的振荡同步性被打破。 因此，模态四波混频成为主要的边带生成机制，超过了几何参量不稳定性。 观测结果与基于微扰分析的理论预测以及(3D + 1)非线性薛定谔方程的完整数值解高度一致。 显示英文摘要

摘要： We introduce the concept of spatial and spectral control of nonlinear parametric sidebands in multimode optical fibers by tailoring their linear refractive index profile. In all cases, the pump experiences Kerr self-cleaning, leading to a bell-shaped profile close to the fundamental mode. Geometric parametric instability, owing to quasi-phase-matching from the grating generated via the Kerr effect by pump self-imaging, leads to frequency multicasting of beam self-cleaning across a wideband array of sidebands. Our experiments show that introducing a gaussian dip in the refractive index profile of a graded index fiber permits to dramatically change the spatial content of spectral sidebands into higher-order modes. This is due to the breaking of oscillation synchronism among fundamental and higher-order modes. Hence modal-four-wave mixing prevails over geometric parametric instability as the main sideband generation mechanism. Observations agree well with theoretical predictions based on a perturbative analysis, and with full numerical solutions of the (3D + 1) nonlinear Schrodinger equation.