Modified angular spectrum algorithm for the propagation of partially coherent beams in optical systems

Area of Science:

• Optics and Photonics
• Computational Physics
• Wave Propagation

Background:

• Diffraction calculations for partially coherent beams are crucial in optical system design.
• Existing modal expansion methods can be computationally intensive, especially for low-coherence beams.
• Efficient algorithms are needed to model beam propagation accurately and quickly.

Purpose of the Study:

• To introduce a modified angular spectrum algorithm for calculating the diffraction of partially coherent beams.
• To enhance computational efficiency for partially coherent beam propagation in optical systems.
• To validate the algorithm's accuracy and speed through numerical simulations.

Main Methods:

• A modified angular spectrum algorithm was developed to directly compute the cross-spectral density at each optical surface.
• Numerical simulations were performed using a Gaussian-Schell model beam in a double-lens array homogenizer system.
• The proposed algorithm's performance was compared against common modal expansion methods.

Main Results:

• The modified angular spectrum algorithm achieves identical intensity distributions to modal expansion methods.
• The proposed algorithm demonstrates significantly higher computational efficiency for low-coherence beams.
• Accuracy and high efficiency of the new algorithm were numerically verified.

Conclusions:

• The modified angular spectrum algorithm provides an accurate and computationally efficient solution for partially coherent beam diffraction.
• This method is particularly advantageous for optical systems with low-coherence beams.
• The algorithm's applicability is limited to systems without cross-coupling effects in the x and y directions.