Laser trimming has become one of the powerful tools for precise manufacturing of alloy resistors that are widely used in electrical vehicles, electrical controlling, and in appliances. In this work, the influence of femtosecond laser trimming is compared with nanosecond laser trimming. The authors found that lasers focused on different heights relative to the sample surface induced significant changes in surface morphologies. The resistance change was systematically investigated as a function of cutting lengths and cutting depths of different laser powers for both lasers. The experiments display that femtosecond laser trimming has a higher precision of the resistance adjustment than nanosecond laser trimming. The periodic ripple structure by the femtosecond laser was investigated at the focus position above, onto, or beneath the surface. The period of a low frequency ripple structure (LFRS) on the ablated groove bottom is about 600–700 nm when the laser focuses just right on the surface but changes to 490–560 nm when focusing above or beneath the surface. The period of a high frequency ripple structure is about 100–380 nm at the vertical direction of LFRS. The period of low frequency ripple on the outside of the groove is smaller than that on the groove bottom for all three focusing cases. The period of the LFRS is not sensitive to the laser power. The range of the resistor value change in the s-polarized light direction of the femtosecond laser is more than that in the p-polarized light direction.

中文翻译：

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合金条电阻器的精密激光微调：飞秒激光与纳秒激光的对比研究

激光微调已成为精密制造合金电阻器的有力工具之一，广泛应用于电动汽车、电气控制和电器。在这项工作中，飞秒激光微调与纳秒激光微调的影响进行了比较。作者发现，激光聚焦在相对于样品表面的不同高度会引起表面形态的显着变化。系统地研究了电阻变化作为两种激光器不同激光功率的切割长度和切割深度的函数。实验表明，飞秒激光微调比纳秒激光微调具有更高的电阻调整精度。在表面上方、上方或下方的焦点位置研究了飞秒激光的周期性波纹结构。当激光恰好聚焦在表面上时，烧蚀凹槽底部的低频波纹结构（LFRS）的周期约为 600-700 nm，但在表面上方或下方聚焦时会变为 490-560 nm。在LFRS的垂直方向上，高频纹波结构的周期约为100-380 nm。三种聚焦情况下，凹槽外侧的低频纹波周期均小于凹槽底部的低频波纹周期。LFRS 的周期对激光功率不敏感。飞秒激光器在s偏振光方向的电阻值变化范围大于在p偏振光方向的变化范围。