Work

Threshold-Governed Inversion of Plasma Chronology at Air–Silicon Interfaces Under Tight Femtosecond Focusing

Year: 2025

Type: article

Abstract: The sequencing of laser-induced plasma formation in multi-material systems is fundamentally governed by the interplay between material ionization thresholds and laser temporal characteristics. This study uncovers a counterintuitive phenomenon where silicon plasma precedes air filamentation at air–silicon interfaces under tight femtosecond laser focusing, which can be attributed to the significant difference in their ionization thresholds. Through time-resolved shadowgraphy with 550 fs resolution, we demonstrate that silicon plasma precedes air filamentation by approximately 3 ps, a temporal discrepancy that can be quantitatively attributed to the 137.5-fold lower ionization threshold of silicon compared to air. The combined influence of the laser temporal contrast and tight focusing geometry modulates this lead time from femtosecond to picosecond scales. This threshold-governed plasma chronology mechanism provides a new paradigm for controlling laser–material interactions, with direct implications for precision manufacturing of layered composites, depth-resolved optical diagnostics, phase-change material characterization, and 3D material architectures.

Source: Photonics

DOI: 10.3390/photonics12060574

Authors: Xian-An Dou, Xin Li, Qing Ye, Yuntao Xie

Institution: State Key Laboratory of Pulsed Power Laser Technology

Language: English

Topic: Laser Material Processing Techniques

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,896

Funders: National University of Defense Technology, State Key Laboratory of Pulsed Power Laser Technology, Natural Science Foundation of Anhui Province