Compact vacuum setup for laser induced plasma etching with optical emission spectrum monitoring.

The article focuses on the development and evaluation of a laser-induced plasma etching (LIPE) setup utilizing a femtosecond laser and a custom-designed compact vacuum chamber filled with SF₆ gas for precision microfabrication. This system enables controlled plasma generation at reduced laser pulse energy thresholds (15–20 μJ) compared to previous reports, with spectral monitoring revealing distinct fluorine and sulfur emission lines that facilitate real-time process analysis. Experimental results demonstrate plasma ignition using various microscope objectives and characterize the effects of numerical aperture and working distance on plasma plume formation. Preliminary surface treatment tests on fused silica showed an increase in surface roughness after LIPE processing, indicating material modification capabilities. The setup provides a foundation for optimizing LIPE parameters and advancing precision etching applications in semiconductor and photonic device manufacturing.