Femtosecond Laser Writing (FLW) has some advantages over competing techniques; it is a direct, highly flexible, and maskless process that can inscribe waveguides in almost any type of transparent material. FLW has proven to produce photonic integrated circuits with innovative design in a deterministic way for several applications, including quantum photonics and microfluidics. Although direct laser writing of waveguides has been extensively studied, there is still an intense search for methods to produce waveguides with lower losses and higher optical quality, because improvements in this sense will impact photonic research and technology. In this work, straight waveguides were directly inscribed into Eagle XG glass samples in a single process step at fabrication depths up to 370 µm. The propagation loss and the mode profile for single-mode waveguides were obtained. The laser pulse energy threshold that triggers the optical breakdown as a function of the depth was measured and used to study its relationship with the resulting waveguide optical properties. A trend between the waveguide losses and the observed pulse energy threshold for optical breakdown was found, which is connected with the microscope objective spherical aberration. It can be useful for finding the best conditions for producing low-loss waveguides. Compared to the waveguides written with the corrected pulses, propagation losses up to 2.5 times smaller were observed in our experiments when applying the strategy presented here. Therefore, by taking advantage of the inherent spherical aberration, the FLW technique can be made capable of much more at even higher intensities than previously possible.

飞秒激光笔迹（FLW）与竞争技术相比有一些优势。它是一种直接、高度灵活且无掩模的工艺，几乎可以在任何类型的透明材料中刻画波导。FLW 已被证明能够以确定性的方式生产具有创新设计的光子集成电路，适用于多种应用，包括量子光子学和微流体。尽管已经对波导的直接激光写入进行了广泛的研究，但仍然在大力寻找生产具有更低损耗和更高光学质量的波导的方法，因为在这个意义上的改进将影响光子研究和技术。在这项工作中，在单个工艺步骤中将直波导直接刻入 Eagle XG 玻璃样品中，制造深度高达 370 µm。获得了单模波导的传播损耗和模式分布。测量作为深度函数触发光击穿的激光脉冲能量阈值，并用于研究其与所得波导光学特性的关系。发现波导损耗与观察到的光学击穿脉冲能量阈值之间的趋势，这与显微镜物镜球差有关。它可用于寻找生产低损耗波导的最佳条件。与使用校正脉冲写入的波导相比，在应用此处介绍的策略时，在我们的实验中观察到传播损耗小 2.5 倍。因此，利用固有的球差，