Calculation of optical forces for arbitrary light beams using the Fourier ray method

Area of Science:

• Optics and Photonics
• Optical Tweezers
• Computational Physics

Background:

• The ray-optics (RO) model is widely used for calculating optical forces in the geometrical optics regime.
• However, the RO model is insufficient for accurately determining optical forces generated by diffractive optical fields and arbitrary structured light beams.

Purpose of the Study:

• To introduce and validate the Fourier ray (FR) method for calculating optical forces exerted by arbitrary incident beams.
• To demonstrate the FR method's capability in predicting optical forces and trapping performance for complex optical fields.

Main Methods:

• The Fourier ray (FR) method combines principles of Fourier optics and geometrical optics.
• FRs are defined as plane waves weighted by the incident beam's Fourier angular spectrum.
• Optical forces on a microsphere were analyzed using both the traditional RO model and the FR method.

Main Results:

• The FR method was validated by comparing calculations for Gaussian and Airy beams with traditional methods.
• Optical forces in three distinct arbitrary structured light beams were successfully demonstrated.
• Simulations confirmed the FR method's ability to evaluate forces from diffractive and complex structured light.

Conclusions:

• The Fourier ray (FR) method provides a universal approach for predicting optical forces in the ray-optics regime, especially for complex optical fields.
• The FR method offers accurate predictions of trapping performance for microspheres interacting with structured and diffractive light beams.