Method for preparing sub-wavelength metal grating through wide-beam femtosecond laser double pulses

Abstract

The invention discloses a method for preparing a sub-wavelength metal grating through wide-beam femtosecond laser double pulses. The femtosecond laser light source outputs a machining light source, the machining light source enters the double-pulse generating device after beam expanding and energy adjusting, the double-pulse generating device outputs femtosecond laser double pulses which are collinear in transmission in space, delayed in time and perpendicular to one another in polarization direction, and the femtosecond laser double pulses irradiate the surface of metal to be machined to prepare the sub-wavelength metal grating after space focusing. By means of the method, efficient controllable preparation of the large-area sub-wavelength metal grating can be achieved, precise mechanicalparts are not needed, masks and chemical corrosive agents are avoided, and the machining environment is loose. The whole preparation process is simple and easy to operate, and secondary damage of stress to the surface of the metal sample can be effectively avoided due to non-contact processing. The surface structure prepared by the method is more regular and uniform in spatial arrangement, the irradiation range of laser spots is large, and the preparation efficiency is high.

Description

technical field [0001] The invention relates to the technical field of laser processing, in particular to a method for preparing a sub-wavelength metal grating with double pulses of a wide-beam femtosecond laser. Background technique [0002] As an important tool for analyzing spectral information, regulating light transmission performance, and detecting the properties of optical and electromagnetic fields, gratings have a pivotal impact on national defense and all aspects of life. Compared with traditional gratings, subwavelength metal gratings have many unique features in terms of optical transmission performance, such as wide response spectrum, high transmittance and extinction ratio, and good polarization correlation, and have become the most promising optical components in the future. Usually, sub-wavelength metal gratings are the core components in spectrometers, monochromators, lasers and other equipment. In addition, because the all-metal grating element has the cha...

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Problems solved by technology

[0004] The present invention aims to overcome the existing femtosecond laser preparation and formation of sub-wavelength gratings on metal surfaces, such as small focused spot irradiation area, low preparation efficiency for large areas, uneven surface structure distribution and poor regularity, etc., especially in metal tungsten. Examples of rapid preparation of large-area subwavelength gratings on the surface of materials with high melting point and high hardness have not been successfully realized

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