Method and application of femtosecond laser direct writing processing with near 4π solid angle by using triangular prism

Abstract

The invention discloses a method and application of femtosecond laser direct writing processing with a triangular prism at a solid angle of nearly 4π, and belongs to the technical field of laser processing. On the side, the three femtosecond laser beams are orthogonally converged on the plane to be processed inside the sample, and a better isotropic three-photon excitation focus (with a near-spherical focus of nearly 4π solid angle) is obtained, thus fundamentally solving the problem of Defocus problem of single beam laser in direct writing process with large buried depth. At the same time, combined with the control of the piezoelectric platform and the sample motion platform, the triangular platform and the sample move synchronously in the Z-axis direction, realizing the continuous adjustment of the processing depth inside the sample, and then obtaining a three-dimensional embedding with a continuously changing processing depth and uniform properties. formula structure.

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. [0002] technical background [0003] 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...

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Problems solved by technology

[0003] 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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