Diffraction-limited near-spherical focal spot with controllable arbitrary polarization using single objective lens

Area of Science:

• Optics and Photonics
• Electromagnetism

Background:

• Generating precise focal spots with controlled polarization is crucial for advanced optical applications.
• Existing methods often require complex setups or specialized components.

Purpose of the Study:

• To develop a novel time-reversal method for creating diffraction-limited focal spots.
• To achieve arbitrary three-dimensional (3D) polarization control using a single objective lens.

Main Methods:

• Utilized Richards-Wolf vectorial diffraction theory.
• Employed three orthogonal dipole antennae and an aplanatic objective lens.
• Calculated optical fields in the pupil plane via time-reversal and verified with vectorial Debye integral.

Main Results:

• Successfully generated a diffraction-limited near-spherical focal spot.
• Demonstrated arbitrary 3D control over the state of polarization.
• Achieved confinement of optical power within a subwavelength volume.

Conclusions:

• The time-reversal method provides a robust way to engineer focal spots with tailored polarization.
• This technique has significant potential for applications in high-resolution imaging, data storage, and nanolithography.