Spurious fringe processing for dielectric metasurface profile measurement using white-light scanning interferometry

Area of Science:

• Optics and Photonics
• Metasurface Technology
• Nanofabrication

Background:

• Dielectric metasurfaces manipulate light using nanostructures with varying geometrical parameters.
• Accurate profile measurement of these nanostructures is crucial for their application.
• White-light scanning interferometry is a common measurement technique, but faces challenges with spurious fringes.

Purpose of the Study:

• To develop an automated signal processing method for accurate dielectric metasurface profile measurement.
• To address and overcome inaccuracies caused by spurious fringes and anomalous coherence signals.
• To enable reliable measurement across all areas of dielectric metasurfaces.

Main Methods:

• Integration of image segmentation for identifying anomalous coherence signals.
• Application of Morlet wavelet transform for extracting fringe envelopes.
• Development of a method suitable for any measured area of dielectric metasurfaces.

Main Results:

• The proposed method effectively distinguishes between top and bottom nanostructure signals.
• It successfully processes spurious fringes and anomalous coherence signals.
• Accurate measurements were achieved on a dielectric metasurface with varying nanopillar densities.

Conclusions:

• The developed signal processing method accurately measures dielectric metasurface profiles.
• It provides a robust solution for handling complex coherence signals and spurious fringes.
• This advancement is vital for the precise characterization of flat optics devices.