Non-uniform angular spectrum method in a complex medium based on iteration.

Area of Science:

• Optics and Photonics
• Computational Electromagnetics
• Wave Propagation

Background:

• Traditional angular spectrum methods require homogeneous media for diffraction propagation calculations.
• Inhomogeneous media present challenges for accurate light field propagation modeling.
• Existing methods like finite element method (FEM) and fast Fourier transform (FFT) beam propagation method (BPM) have limitations in speed, memory, and handling non-paraxial cases.

Purpose of the Study:

• To develop an iterative non-uniform angular spectrum method for accurate diffraction propagation in complex, inhomogeneous media.
• To overcome the limitations of traditional methods in non-uniform environments.
• To provide a computationally efficient and versatile alternative for light field propagation.

Main Methods:

• Proposed an iterative non-uniform angular spectrum method.
• Implemented phase pre-processing in the spatial domain.
• Performed diffraction calculations in the spatial frequency domain.

Main Results:

• Successfully solved the diffraction propagation problem for light fields in complex media.
• Validated the method through theoretical formulation, numerical simulations, and experimental investigation.
• Demonstrated faster computation and reduced memory requirements compared to FEM.
• Enabled computation of non-paraxial cases, outperforming standard FFT-BPM.

Conclusions:

• The non-uniform angular spectrum method is a valid and effective approach for light propagation in inhomogeneous media.
• The proposed method offers significant advantages in terms of speed, memory efficiency, and computational scope.
• This advancement provides a more robust tool for analyzing complex optical phenomena.