Analysis and research on the processing threshold of femtosecond laser

Abstract

In this work, the intensity distribution formula of the focused femtosecond (fs) laser beam is derived. MATLAB was used to establish the light intensity distribution model of the focused fs laser under the processing condition, and the light intensity of focused fs laser under different laser power was simulated. Then the fs laser processing platform was built. The glass was etched by fs laser, and the SU-8 photoresist was processed by fs laser two-photon polymerization (2PP). By adjusting the change of laser power, the etching and polymerization lines of different sizes are obtained. Based on the simulation results and experimental results, the estimated etching threshold of the glass using the fs laser is 5.096 6×10¹⁶ W/m², and the estimated processing threshold of SU-8 photoresist by 2PP using the fs laser is 1.194 2×10¹⁴ W/m². This work is helpful to further analyze the applications of fs laser processing. It provides guidance and reference for different kinds of fs laser processing methods.

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