Window functions for self-consistency evaluation of optical constants

Area of Science:

• Materials Science
• Optics
• Condensed Matter Physics

Background:

• Optical-constant data from diverse sources often exhibit inconsistencies.
• Sum rules assess data self-consistency across the electromagnetic spectrum.
• Existing window functions (WFs) for spectrally-resolved analysis can be unstable.

Purpose of the Study:

• To develop new, more stable window functions (WFs) for evaluating the self-consistency of optical-constant data.
• To enhance the accuracy of identifying spectral ranges responsible for data inconsistencies.
• To differentiate data inconsistencies from numerical instabilities in analysis.

Main Methods:

• Developed two novel WFs utilizing smooth weight functions (linear or polynomial).
• Tested new WFs on exact optical constants with coarse sampling.
• Applied new WFs to experimental optical-constant data sets for Aluminum (Al) and Gold (Au).

Main Results:

• The new WFs significantly reduce instability in sum-rule calculations compared to previous methods.
• Testing on exact data demonstrated improved self-consistency evaluation.
• Analysis of experimental Al and Au data revealed specific ranges of inconsistency, attributed to the data itself.

Conclusions:

• The developed WFs offer enhanced stability and reliability for spectrally-resolved self-consistency checks.
• These WFs enable more confident identification of genuine data inconsistencies.
• The study validates the utility of WFs for analyzing optical-constant data quality.