Design of optical notch filters using apodized thickness modulation

Area of Science:

• Optical Engineering
• Materials Science

Background:

• Discrete layer notch filters are crucial optical components.
• Achieving low ripple and error tolerance in filter design is challenging.
• Traditional methods often require extensive numerical optimization.

Purpose of the Study:

• To present an apodized thickness design method for discrete layer notch filters.
• To demonstrate error tolerance and low passband ripple without numerical optimization.
• To validate the design method through theoretical and experimental analysis.

Main Methods:

• Utilizing apodization functions (Gaussian, cosine squared, quintic) for thickness design.
• Fabricating single-notch and multi-notch filters using ion beam deposition.
• Comparing theoretical designs with experimental measurements.

Main Results:

• The apodized design method yields filters with low ripple in passband regions.
• Experimental results show good agreement with theoretical predictions.
• The designs exhibit low sensitivity to layer thickness errors during deposition.

Conclusions:

• The proposed apodized thickness design method is effective for discrete layer notch filters.
• The method offers inherent error tolerance, simplifying the fabrication process.
• Apodized designs are robust against variations in the deposition process.