Moreno-Zarate Pedro, Muñoz Francisco, Sotillo Belen, Macias-Montero Manuel, Atienzar Julia, Garcia-Pardo Marina, Fernandez Paloma, Serna Rosalia, Solis Javier
Electronic Engineering Department, Higher Technological Institute of Acatlan Osorio, Carretera Acatlan-San Juan Ixcaquistla k.m. 5.5, Acatlan de Osorio 74949, Mexico.
Institute of Ceramics and Glass (ICV, CSIC), Kelsen 5, 28049 Madrid, Spain.
Materials (Basel). 2020 Mar 11;13(6):1275. doi: 10.3390/ma13061275.
The local modification of the composition of glasses by high repetition femtosecond laser irradiation is an attractive method for producing photonic devices. Recently, the successful production of waveguides with a refractive index contrast (Δn) above 10 by fs-laser writing has been demonstrated in phosphate glasses containing LaO and KO modifiers. This large index contrast has been related to a local enrichment in lanthanum in the light guiding region accompanied by a depletion in potassium. In this work, we have studied the influence of the initial glass composition on the performance of waveguides that are produced by fs-laser induced element redistribution (FLIER) in phosphate-based samples with different La and K concentrations. We have analyzed the contribution to the electronic polarizability of the different glass constituents based on refractive index measurements of the untreated samples, and used it to estimate the expected index contrast caused by the experimentally measured local compositional changes in laser written guiding structures. These estimated values have been compared to experimental ones that are derived from near field images of the guided modes with an excellent agreement. Therefore, we have developed a method to estimate before-hand the expected index contrast in fs-laser written waveguides via FLIER for a given glass composition. The obtained results stress the importance of considering the contribution to the polarizability of all the moving species when computing the expected refractive index changes that are caused by FLIER processes.
通过高重复频率飞秒激光辐照对玻璃成分进行局部改性是制造光子器件的一种有吸引力的方法。最近，在含有LaO和KO改性剂的磷酸盐玻璃中，通过飞秒激光写入成功制备了折射率对比度（Δn）高于10的波导。这种大的折射率对比度与导光区域中镧的局部富集以及钾的贫化有关。在这项工作中，我们研究了初始玻璃成分对通过飞秒激光诱导元素重新分布（FLIER）在不同La和K浓度的磷酸盐基样品中制备的波导性能的影响。我们基于未处理样品的折射率测量分析了不同玻璃成分对电子极化率的贡献，并利用它来估计由激光写入导光结构中实验测量的局部成分变化引起的预期折射率对比度。这些估计值已与从导模近场图像得出的实验值进行了比较，结果吻合得很好。因此，我们开发了一种方法，对于给定的玻璃成分，通过FLIER预先估计飞秒激光写入波导中的预期折射率对比度。所得结果强调了在计算由FLIER过程引起的预期折射率变化时，考虑所有移动物种对极化率贡献的重要性。
