Three-dimensional shape-controllable focal spot array created by focusing vortex beams modulated by multi-value...

Area of Science:

• Optics and Photonics
• Microscopy and Imaging
• Materials Science

Background:

• Generating controllable focal spot arrays is crucial for advanced optical applications.
• Existing methods often lack precise control over three-dimensional (3D) arrangement and individual spot characteristics.

Purpose of the Study:

• To propose and demonstrate a novel method for creating 3D shape-controllable focal spot arrays.
• To enable precise manipulation of focal spot number, spacing, and intensity.
• To explore the potential for advanced optical applications.

Main Methods:

• Utilized a two-dimensional (2D) pure-phase modulation grating combined with axial shifting pure-phase modulation.
• Employed a four-quadrant phase distribution unit at the back aperture of a high numerical aperture (NA) objective.
• Designed 1D and 2D gratings using an optimized algorithm for controlled diffraction spot generation.
• Incorporated spatially shifted multi vortex beams to manipulate individual focal spot shape and intensity.

Main Results:

• Demonstrated the generation of equally spaced diffraction spots with identical intensity using 1D gratings.
• Achieved 2D diffraction spot arrays where the number of spots is determined by phase-divided areas.
• Successfully created 3D focal spot arrays by combining axial translation phase modulation.
• Showcased the ability to manipulate the shape and intensity of individual spots within the 3D array.

Conclusions:

• The proposed method effectively generates 3D shape-controllable focal spot arrays.
• This technique offers precise control over the spatial arrangement and characteristics of multiple focal spots.
• Potential applications include metamaterial fabrication, parallel optical micromanipulation, and multifocal multiphoton microscopy.