Method for carrying out nearly 4pi solid angle femtosecond laser direct writing processing through triangular prism and application thereof

Abstract

The invention discloses a method for carrying out nearly 4pi solid angle femtosecond laser direct writing processing through a triangular prism and application thereof, and belongs to the technical field of laser processing. Three identical laser beams are controlled to perpendicularly irradiate on three side surfaces of the triangular prism, the three femtosecond laser beams are made to convergeorthogonally on the to-be-processed plane inside a sample, a three-photon stimulating focus with better isotropy (a nearly-spherical focus with a nearly 4pi solid angle) is obtained, and therefore theproblem of defocusing during large-setting-depth direct writing processing with a single laser beam is fundamentally solved. In combination with control over a piezoelectric platform and a sample movement platform, the triangular prism and the sample are synchronously moved in the Z-axis direction, continuous adjustment of the processing depth in the sample is realized, and a three-dimensional embedded type structure with the continuously changing processing depth and uniform property is further obtained.

Description

technical field [0001] The invention belongs to the technical field of laser processing, and specifically relates to the use of triangular prisms for three-photon excitation to improve the defocus problem of femtosecond laser large embedded depth direct writing processing. By dividing the femtosecond laser into three beams and adjusting the three beam pulses Synchronized with time, the three sub-beams of femtosecond laser pulses are incident on the side of the triangular prism to improve the defocus problem of femtosecond laser internal processing, so as to realize the three-dimensional embedding with continuously variable processing depth based on the principle of multi-photon excitation Direct write processing of formula structure. technical background [0002] Laser processing is widely used in the field of micro-nano processing due to its three-dimensional processing capability and low processing cost. However, since its working substance is light, after light is injecte...

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Problems solved by technology

[0002] Laser processing is widely used in the field of micro-nano processing due to its three-dimensional processing capability and low processing cost. However, since its working substance is light, after light is injected into the material from air, due to the change of the refractive index, it will produce Serious defocusing problem, this kind of defocusing will cause the elongation of the laser focus, resulting in the processing of the waveguide structure is elliptical or almost long, such a waveguide will have different losses for different polarizations of light, even if using The method of increasing the numerical aperture, such as using an oil immersion objective lens with NA=1.45, will also have serious defocusing problems inside the material. Defocusing will lead to waveguide shapes with different processing depths and different light guiding characteristics. The defocus problem caused by the second laser processing inside the bulk material generally uses high repetition frequency laser pulses, cylindrical lens beam shaping, slit beam shaping, laser multiple scanning, processing stress field damage lines, spatial light modulators, etc.

None of these methods can fundamentally solve the problem of femtosecond laser defocusing, so there is an urgent need for a method that can fundamentally solve the defocusing problem of femtosecond laser deep processing

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