Modulation of high-quality internal multifoci based on modified three-dimensional Fourier transform

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Generating multiple, precisely controlled focal points within materials is crucial for advanced applications like 3D printing and laser processing.
• Existing methods often struggle with uniformity and arbitrary control over multifocal patterns.

Purpose of the Study:

• To develop an efficient and versatile method for generating arbitrary three-dimensional (3D) parallel multifoci inside materials.
• To improve the uniformity and axial control of these multifoci.

Main Methods:

• Modified the Ewald cap model by adjusting its radius to account for optical parameters (numerical aperture, refractive index).
• Employed a single Fourier transform (FT) for calculating the 3D intensity distribution.
• Introduced an adaptive weight coefficient to enhance multifoci uniformity.
• Adjusted the axial resolution of the Ewald cap for improved axial uniformity.

Main Results:

• Achieved a significant improvement in 3D multifoci uniformity from 81.3% to 98.9% using the adaptive weight coefficient.
• Enhanced axial multifoci uniformity from 85.9% to 99.7% by adjusting the Ewald cap's axial resolution.
• Successfully demonstrated the generation of 1D, 2D, and 3D structures within fused silica, matching simulation predictions.
• Experimental validation of arbitrary intensity distribution control using a custom
• H-U-S-T
• structure.

Conclusions:

• The proposed method offers an efficient and accurate way to generate arbitrary 3D parallel multifoci within materials.
• The technique provides high uniformity and precise control over light distribution, opening possibilities for novel material processing applications.
• Experimental results confirm the method's capability to realize customized intensity distributions for complex structures.