Previous approaches for laser beam cutting of sapphire often lead to chipping, debris, large kerf widths, tapering and high surface roughness or nonuniform surfaces. Laser beam stealth dicing can remove kerf width and tapering, reduce defects. However, sidewall uniformity is poor as part of the material is laser cut and part is broken by an external mechanical force. In previous approaches of Bessel beam full depth cutting of sapphire, uniformity can be improved. However, the sidewall surface roughness is poor. There has been lack of an ideal solution to achieving minimum defects and low surface roughness. Here we show a much improved sapphire cutting method with a femtosecond Bessel beam achieving a 200 nm Ra cut surface roughness, which is almost an order of magnitude improvement over the previous Bessel beam cutting approaches without losing the uniformity. By using a diameter reduced Gaussian beam passing through a 20° physical angle axicon lens, a highly uniform non-diffraction Bessel beam is generated. Under circular polarization, the effects of Bessel beam scanning speed on flexural strength and the sidewall surface roughness are analyzed for cutting sapphire sheets of 0.38 mm, 1 mm, and 1.5 mm in thickness. Zero taper, zero kerf width, free of debris/chipping sapphire cutting with both straight and curved lines are demonstrated. The fundamental mechanisms involved are discussed. The uniformity of Bessel beam and appropriate separation of pulses have been identified as the key factors for achieving the low surface roughness.

先前用于切割蓝宝石的激光束的方法通常会导致碎裂，碎屑，大切口宽度，逐渐变细和高表面粗糙度或不均匀表面。激光束隐形切割可消除切口宽度和锥度，减少缺陷。然而，由于材料的一部分被激光切割并且部分被外部机械力破坏，侧壁均匀性差。在贝塞尔光束蓝宝石全深度切割的先前方法中，可以提高均匀性。但是，侧壁表面粗糙度差。缺少实现最小缺陷和低表面粗糙度的理想解决方案。在这里，我们展示了一种经过改进的蓝宝石切割方法，飞秒贝塞尔光束实现了200 nm Ra的切割表面粗糙度，与以前的贝塞尔光束切割方法相比，这几乎提高了一个数量级，而又不会失去均匀性。通过使用直径减小的高斯光束通过20°物理角轴锥透镜，可以生成高度均匀的无衍射贝塞尔光束。在圆极化下，分析了贝塞尔光束扫描速度对弯曲强度和侧壁表面粗糙度的影响，以切割厚度为0.38 mm，1 mm和1.5 mm的蓝宝石片。展示了零锥度，零切缝宽度，直线和曲线均无碎屑/碎蓝宝石切割。讨论了涉及的基本机制。贝塞尔光束的均匀性和适当的脉冲间隔已被确定为实现低表面粗糙度的关键因素。通过使用直径减小的高斯光束通过20°物理角轴锥透镜，可以生成高度均匀的无衍射贝塞尔光束。在圆极化下，分析了贝塞尔光束扫描速度对弯曲强度和侧壁表面粗糙度的影响，以切割厚度为0.38 mm，1 mm和1.5 mm的蓝宝石片。展示了零锥度，零切缝宽度，直线和曲线均无碎屑/碎蓝宝石切割。讨论了涉及的基本机制。贝塞尔光束的均匀性和适当的脉冲间隔已被确定为实现低表面粗糙度的关键因素。通过使用直径减小的高斯光束通过20°物理角轴锥透镜，可以生成高度均匀的无衍射贝塞尔光束。在圆极化下，分析了贝塞尔光束扫描速度对弯曲强度和侧壁表面粗糙度的影响，以切割厚度为0.38 mm，1 mm和1.5 mm的蓝宝石片。展示了零锥度，零切缝宽度，直线和曲线均无碎屑/碎蓝宝石切割。讨论了涉及的基本机制。贝塞尔光束的均匀性和适当的脉冲间隔已被确定为实现低表面粗糙度的关键因素。分析了贝塞尔光束扫描速度对弯曲厚度为0.38 mm，1 mm和1.5 mm的蓝宝石片的弯曲强度和侧壁表面粗糙度的影响。展示了零锥度，零切缝宽度，直线和曲线均无碎屑/碎蓝宝石切割。讨论了涉及的基本机制。贝塞尔光束的均匀性和适当的脉冲间隔已被确定为实现低表面粗糙度的关键因素。分析了贝塞尔光束扫描速度对弯曲厚度为0.38 mm，1 mm和1.5 mm的蓝宝石片的弯曲强度和侧壁表面粗糙度的影响。展示了零锥度，零切缝宽度，直线和曲线均无碎屑/碎蓝宝石切割。讨论了涉及的基本机制。贝塞尔光束的均匀性和适当的脉冲间隔已被确定为实现低表面粗糙度的关键因素。