Polarization Properties in Apertureless-Type Scanning Near-Field Optical Microscopy

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Apertureless scanning near-field optical microscopy (a-SNOM) is a powerful technique for high-resolution imaging.
• Understanding the polarization properties of a-SNOM is crucial for advanced applications.
• Previous studies have explored various aspects of SNOM, but detailed polarization analysis remains an active research area.

Purpose of the Study:

• To experimentally measure and theoretically analyze the polarization properties of apertureless scanning near-field optical microscopy (a-SNOM).
• To investigate the wave plate behavior of a-SNOM and its representation using a Jones matrix.
• To differentiate between near-field scattered signals and background reflected signals using lock-in detection.

Main Methods:

• Experimental measurements of polarization properties using a-SNOM.
• Finite-difference time-domain (FDTD) simulations for theoretical analysis.
• Lock-in detection technique for signal decomposition.
• Generation of polarization images with 1° angular resolution.

Main Results:

• Polarization properties are maintained within the a-SNOM system.
• The a-SNOM system effectively functions as a wave plate, describable by a Jones matrix.
• Measured signals were successfully decomposed into near-field scattered and background reflected components.
• FDTD analysis confirmed that light between the tip and sample is predominantly p-polarized.

Conclusions:

• The study confirms the wave plate nature of a-SNOM, enabling precise polarization control and analysis.
• The findings provide a deeper understanding of light-matter interactions at the nanoscale within a-SNOM.
• The ability to distinguish between near-field and background signals enhances the reliability of polarization imaging in a-SNOM.