Numerical design of three-dimensional gradient refractive index structures for beam shaping

Area of Science:

• Optics and Photonics
• Computational Electromagnetics

Background:

• Gradient refractive index (GRIN) materials offer unique light manipulation capabilities.
• Controlling beam propagation and compensating for diffraction are crucial in optical systems.

Purpose of the Study:

• To demonstrate a numerical design method for GRIN beam shapers.
• To achieve efficient optical field transformations with minimal artifacts.

Main Methods:

• Utilized a paraxial scalar wave beam propagation model.
• Employed phase retrieval techniques for profile determination.
• Designed a three-dimensional refractive index profile Δn(x, y, z).

Main Results:

• Successfully controlled and compensated for diffraction effects like beam expansion.
• Achieved efficient beam transformation with no coherent artifacts.
• Demonstrated a design using small refractive index changes (Δn < 10⁻³) over 10 mm.

Conclusions:

• The numerical design method is effective for creating GRIN beam shapers.
• GRIN profiles can precisely tailor beam characteristics during propagation.
• This approach enables advanced optical field control for various applications.