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Analysis of non-quarter-wave grating by a modified Fourier-transform method
Tim K L Wong1, Lukasz Brzozowski, Edward H Sargent
1Department of Electrical and Computer Engineering, University of Toronto, Ontario, Canada. tim.wong@utoronto.ca
Applied Optics
|November 21, 2002
Summary
The Fourier-transform method for optical gratings is inaccurate near unity reflectance. A modified Fourier-transform method is extended for accurate reflectance spectrum calculation in non-quarter-wave gratings.
Area of Science:
- Optics
- Materials Science
- Computational Physics
Background:
- The standard Fourier-transform method struggles with accuracy for optical gratings, especially near unity reflectance.
- Bovard's modified Fourier transform method offers high accuracy for quarter-wave gratings.
Purpose of the Study:
- To extend Bovard's modified Fourier transform method to non-quarter-wave gratings.
- To develop a simplified method for accurate reflectance spectrum calculation in complex grating structures.
Main Methods:
- Extension of Bovard's modified Fourier transform method.
- Application to apodized linear and nonlinear optical gratings.
- Numerical validation of the extended method.
Main Results:
- The extended method accurately calculates reflectance spectra for non-quarter-wave gratings.
- Demonstrated accurate results for both apodized linear and optically apodized nonlinear gratings.
- The simplified approach maintains accuracy across different grating types.
Conclusions:
- The modified Fourier transform method is successfully extended beyond quarter-wave gratings.
- This work provides a robust and accurate computational tool for analyzing optical grating reflectance spectra.
- The method is applicable to a wider range of optical grating designs, including apodized structures.