Characterization of a subwavelength-scale 3D void structure using the FDTD-based confocal laser scanning microscopic...

Area of Science:

• Photonics and Nanotechnology
• Materials Science
• Microscopy

Background:

• Characterizing subwavelength-scale structures is crucial for advanced optical applications.
• Fabrication of 3D nanostructures requires precise imaging techniques.
• Existing methods may lack the resolution or accuracy for subwavelength voids.

Purpose of the Study:

• To propose and evaluate a novel confocal laser scanning microscopic (CLSM) image mapping technique.
• To accurately characterize subwavelength-scale three-dimensional (3D) void structures in a polymer matrix.
• To demonstrate the utility of finite-difference time domain (FDTD) calculations for this purpose.

Main Methods:

• Utilized a finite-difference time domain (FDTD) simulation method with a focused Gaussian beam and Berenger's perfectly matched layer absorbing boundary condition.
• Employed angular spectrum analysis for wave propagation.
• Performed xz-scanned 3D void structure imaging and compared simulation with experimental results.

Main Results:

• Achieved well-matched simulation and experimental results for the 3D void structure.
• Successfully characterized the exact position of the subwavelength-scale void.
• Determined the topological shape factor of the fabricated void structure.

Conclusions:

• The proposed CLSM image mapping technique based on FDTD is effective for characterizing subwavelength 3D void structures.
• The method provides accurate positional and shape information.
• This technique has broad applicability in 3D near-field microscopy, optical trapping, and nanophotonics.