Wang Andong, Das Amlan, Fedorov Vladimir Yu, Sopeña Pol, Tzortzakis Stelios, Grojo David
Aix Marseille University, CNRS, LP3 UMR7341, Marseille, France.
Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing, China.
Nat Commun. 2025 Jul 22;16(1):6733. doi: 10.1038/s41467-025-61983-9.
Ultrafast laser three-dimensional writing has made breakthroughs in manufacturing technologies. However, it remains rarely adopted for semiconductor technologies due to in-chip propagation nonlinearities causing a lack of controllability for intense infrared light. To solve this problem, plasma-optics concepts are promising since ultrashort laser pulses, even if inappropriate for direct writing, can readily inject high-density free-carriers inside semiconductors. To achieve highly localized and reliable processing, we create plasma seeds with tightly focused pre-ionizing femtosecond pulses. We show how critical density conditions can be used for extremely confined energy deposition with a synchronized writing irradiation and create ~ 1-µm-sized isotropic modifications inside silicon. Drastic improvement is also found on the material change controllability leading to unique demonstrations including rewritable optical memories (>100 writing/erasure cycles) and graded-index functionalities. By solving its controllability issues with critical plasma seeds, we show the potential of ultrafast laser writing for flexible fabrication of reconfigurable monolithic silicon-based optical devices.
超快激光三维写入技术在制造工艺方面取得了突破。然而，由于芯片内传播非线性导致对强红外光缺乏可控性，该技术在半导体技术中仍很少被采用。为了解决这个问题，等离子体光学概念很有前景，因为即使超短激光脉冲不适合直接写入，也能轻易地在半导体内部注入高密度自由载流子。为了实现高度局部化和可靠的加工，我们用紧聚焦的预电离飞秒脉冲产生等离子体种子。我们展示了如何利用临界密度条件，通过同步写入辐照实现极其受限的能量沉积，并在硅内部创建约1微米大小的各向同性改性。在材料变化可控性方面也有显著改善，从而实现了包括可重写光学存储器（>100次写入/擦除循环）和渐变折射率功能等独特演示。通过用临界等离子体种子解决其可控性问题，我们展示了超快激光写入在灵活制造可重构单片硅基光学器件方面的潜力。
