Simplified analysis of sub-wavelength triangular gratings by simplified modal method.

Area of Science:

• Optics and Photonics
• Materials Science and Engineering

Background:

• Triangular gratings are crucial optical components, but their analysis is complex.
• Existing methods, like the simplified modal method, are computationally intensive for triangular gratings.

Purpose of the Study:

• To propose a phase-equivalence between triangular gratings and blazed structures.
• To simplify the analysis and modeling of triangular gratings.
• To develop a method for non-destructive height estimation of triangular gratings.

Main Methods:

• Theoretical modeling establishing phase-equivalence.
• Finite element simulations for model verification.
• Fabrication of a triangular grating in quartz.

Main Results:

• An equation for the phase introduced by a triangular grating was derived.
• Finite element simulations confirmed the proposed phase-equivalence model.
• A fabrication method for quartz triangular gratings was demonstrated.

Conclusions:

• The phase-equivalence offers a simplified analytical approach for triangular gratings.
• The developed theory and optical testing provide a non-destructive method for in-situ height measurement during dry etching.
• This research facilitates efficient design and fabrication of optical gratings.