A femtosecond laser emits pulses that last one quadrillionth of a second. Because the energy arrives in an extremely short burst, it can remove material by ablation before much heat spreads into the surrounding area. That makes it useful for precise cutting, drilling, and surface modification where ordinary heating would damage nearby structures.
In cyber security, this kind of precision matters in hardware research and defense. Labs use femtosecond lasers to open chip packages, expose traces, inspect semiconductor layers, and study tamper resistance without destroying the whole device. The same capability can also be abused in advanced hardware attacks, where a very fine beam may help remove microscopic material, alter a component, or reach protected circuitry. The key security lesson is that high precision tools can support both careful analysis and stealthy physical tampering.