Guided Mode Resonance Grating for Rainbow-Free Optical Sampling
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Solution Overview
Problem
Conventional diffractive grating structures produce visually obtrusive rainbows due to their dispersive nature, making them unsuitable for wavelength selective sampling of light, especially in applications requiring transparency.
Innovation Solution
A nanoengineered optical coating with a thin, ultra-thin grating layer that supports guided mode resonance, allowing selective redirection of light with specific wavelength, polarization, and angle properties while suppressing undesired diffraction orders, thereby minimizing the rainbow effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional diffractive grating structures are used for wavelength selective sampling, then light can be separated by wavelength, but visually obtrusive rainbows are produced
Solution Approach 1:
The patent changes the operating parameters of the diffraction grating by operating it in a resonant regime at specific wavelengths and angles, rather than in the conventional non-resonant regime. This resonant operation selectively enhances diffraction at desired wavelengths while suppressing the rainbow effect at other wavelengths, resolving the contradiction between wavelength selectivity and visual obtrusiveness
Solution Approach 2:
The patent exploits optical resonance analogous to mechanical vibration, where the grating structure resonates at specific wavelengths and angles of incidence. This resonant behavior creates strong, selective diffraction peaks while suppressing other wavelengths, achieving wavelength selectivity without the continuous rainbow spectrum produced by conventional gratings
2Productivity
If diffraction efficiency is increased for wavelength selective sampling, then more light is redirected to desired wavelengths, but transmission of other wavelengths is reduced
Solution Approach 1:
The patent changes the operational parameters by operating the grating in a resonant regime at specific wavelengths and angles, which dramatically increases diffraction efficiency at those parameters while maintaining high transmission at all other wavelengths and angles. This resonant enhancement is highly selective, so energy is concentrated only where needed rather than being lost across the entire spectrum
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high transmission and efficient redirection of light with negligible absorption of desired wavelengths, making the structure virtually invisible and suitable for applications like augmented reality, eye tracking, and optical communication.
Implementation Method 1
This structure supports a guided mode resonance (quasi-guided waveguide mode). The grating layer can be capable of absorbing light that excited the guided resonance with predetermined spectral content.
Implementation Method 2
grating sampling structures that are virtually rainbow-free are provided. More specifically, a thin, nanoengineered optical coating is provided that facilitates extraction of light with a very select range of wavelengths
Implementation Method 3
The grating layer can be capable of absorbing light that excited the guided resonance with predetermined spectral content.
Data Source
AI summary
Waveguide enhanced resonant diffraction is provided in grating structures having negligible non-resonant diffraction by the grating. This is done by making the grating thickness much less than any relevant wavelength, and by having the grating in proximity to a waveguide for diffractive coupling to and from a mode of the waveguide. Material absorption in the grating material can be used to suppress undesired diffraction orders. The resulting structures can provide rainbow-free diffractive optical sampling.