Synthesis of supergratings by fourier methods
US6415081B1 · kind B1 · utility
Inventors
Key dates
| Filing date | Aug 4, 2000 |
| Grant date | Jul 2, 2002 |
| Priority date | — |
| Expiry date | Sep 11, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B2006/02166
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention relates to a method for synthesizing supergratings using Fourier analysis. The method divides the synthesis process into two stages: synthesis of an “analog” grating profile, followed by a quantization step. The method provides a generalized procedure for analog synthesis by drawing on the Fourier approximation and on finite-inpulse-response (FIR) filter design theory, while it interprets the simple threshold quantization as a “zeroth order” Delta-Sigma Modulator, which it improves. The method of designing a supergrating for a waveguide includes providing a reflectance spectrum in at least one spectral band to be produced by a supergrating in a waveguide, the reflectance spectrum having specified reflectance features, transforming the reflectance spectrum to a Fourier domain representation having Fourier-domain features, computationally synthesizing an analog refractive index profile corresponding to the Fourier-domain representation and transforming the analog refractive index profile to a binary or multi-level refractive index profile representation in such a way as to conserve Fourier-domain information within the spectral band.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.