Near-Field Vortex Beams Diffraction on Surface Micro-Defects and Diffractive Axicons for Polarization State...

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Vortex Gaussian laser beams are crucial for advanced optical applications.
• Micro-optical elements, including surface micro-defects, are essential for manipulating light at small scales.

Purpose of the Study:

• To investigate the diffraction of vortex Gaussian laser beams by micro-optical surface defects.
• To determine if these defects can recognize the polarization state and dimensions of micro-defects.

Main Methods:

• Simulated light propagation through micro-defects using the finite difference time domain (FDTD) method.
• Analyzed diffraction patterns for different defect types (protrusion/depression, circle/square) and sizes.
• Compared micro-defect focusing properties with diffractive axicons.

Main Results:

• Demonstrated that micro-defects can act as sensors to recognize four types of laser polarization (linear, circular, radial, azimuthal).
• Showcased the ability to recognize micro-defect dimensions (size, protrusion/depression).
• Achieved sub-wavelength focusing, with a silicon cylinder creating a spot of 0.28λ Full Width at Half Maximum (FWHM).

Conclusions:

• Micro-defects serve as effective sensors for both laser polarization states and their own dimensional characteristics.
• The findings open possibilities for novel micro-optic sensors and advanced light manipulation techniques.
• Sub-wavelength focusing capabilities highlight the potential for high-resolution optical applications.