Verification and comparison of a fast fourier transform-based full diffraction method for tilted and offset planes

Area of Science:

• Computational optics
• Diffraction theory
• Optical system analysis

Background:

• The Rayleigh-Sommerfeld diffraction integral is crucial for modeling optical systems.
• Evaluating this integral, especially for tilted and offset planes, has been computationally intensive.
• A novel fast Fourier transform (FFT)-based approach has been developed to address these computational challenges.

Purpose of the Study:

• To validate the newly developed FFT-based method for calculating the Rayleigh-Sommerfeld diffraction integral.
• To assess the accuracy, speed, and memory requirements of the FFT method in comparison to direct integration (DI).
• To determine the applicability of the FFT method across various optical modeling scenarios.

Main Methods:

• Comparison of the FFT-based method with direct integration (DI) for calculating the Rayleigh-Sommerfeld integral.
• Evaluation of accuracy, computational speed, and memory usage for both methods.
• Testing the methods on tilted and offset planes within integrated optical systems.

Main Results:

• The FFT-based method demonstrates a significant speed improvement, being 228 times faster than the DI method for a 500 µm x 500 µm computational window.
• The FFT method requires 14 times more memory compared to the DI method.
• The FFT method provides a valid and efficient alternative for high-speed evaluation of integrated optical systems.

Conclusions:

• The FFT-based method is a highly efficient and validated tool for calculating diffraction integrals in optical system design.
• This method enables high-speed analysis of integrated optics, overcoming limitations of traditional direct integration.
• Further assessment of its applicability and potential limitations in diverse optical modeling situations is warranted.