Dielectric Grating for Near-Field Beam Deviation
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Solution Overview
Problem
Current optical devices struggle to control and precisely position electromagnetic beams at the subwavelength scale, particularly in manipulating the focal spot position and orientation, which is essential for advanced nano-photonic applications but faces challenges due to high absorption losses and fabrication difficulties in plasmonic lenses, and lacks reliable solutions for light deviation functions in near-field zones.
Innovation Solution
A diffraction grating design utilizing a substrate with a periodic array of grating unit cells made of two dielectric materials with different refractive indices, forming a trapezoidal cross-section, which enables non-symmetrical response for diffraction orders and controls the position and direction of nanojet beams by varying refractive indices and dimensions, allowing for light deviation in the near-field zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If plasmonic lenses are used to achieve subwavelength-scale focusing, then the focal spot position can be controlled, but high absorption losses occur
Solution Approach 1:
The patent changes the material parameter from plasmonic materials to dielectric materials, fundamentally altering the optical properties to reduce absorption losses while maintaining subwavelength focusing capability through careful design of dielectric constant and geometric parameters
Solution Approach 2:
The patent employs composite dielectric structures with multiple materials having different refractive indices arranged in specific geometries, creating effective medium properties that enable subwavelength control without the losses inherent in single-material plasmonic systems
2Ease of operation
If conventional diffraction gratings are used, then light diffraction is achieved, but precise control of beam orientation and focal spot position is lacking
Solution Approach 1:
The patent applies local quality by varying the geometric parameters (width, height, shape) and material properties of individual grating elements at different positions across the grating structure, enabling spatially selective control of diffraction characteristics to achieve precise beam orientation and focal positioning
Solution Approach 2:
The patent introduces design flexibility and adjustability by making grating parameters variable rather than fixed, allowing dynamic optimization of diffraction patterns for different operational requirements through parameter tuning
3Measurement precision
If subwavelength-scale optical manipulation is implemented, then nano-photonic application performance is enhanced, but fabrication difficulties increase
Solution Approach 1:
The patent transitions from two-dimensional planar patterns to three-dimensional structured grating elements with controlled depth and vertical profiles, enabling subwavelength optical control through volumetric geometry that can be fabricated using standard vertical etching and deposition techniques
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 proposed diffraction grating achieves efficient light deviation and beam control in the near-field zone, enhancing performance characteristics and compatibility with established micro- and nano-fabrication techniques, suitable for applications in AR/VR glasses, solar panels, and other nano-photonic devices.
Implementation Method 1
a diffraction grating for diffracting light comprising a substrate and a plurality of grating unit cells positioned on said substrate surface
Implementation Method 2
a first block of a first dielectric material with a first width W1, along an x-axis, a height H along a z-axis and a second refractive index n2
Implementation Method 3
Grating unit cells form a periodic array of grating unit cells which are parallel to each other on said substrate surface... a first block of a first dielectric material... a second block of a second dielectric material
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5
AI summary
In one embodiment of the disclosure, it is proposed a diffraction grating for diffracting light comprising a substrate and a plurality of grating unit cells positioned on the substrate surface. The grating unit cells form a periodic array of grating unit cells which are parallel to each other on said substrate surface or are along a same axis. The diffraction grating is associated with a three-dimensional Cartesian coordinates system defined by axis x, y and z, wherein the z-axis being normal to said diffraction grating. A cross-section of a grating unit cell, in a vertical xz plane, comprises a homogeneous dielectric host medium with a first refractive index n1, embedding at least a first block of a first dielectric material with a first width W1 along an x-axis, a height H along a z-axis and a second refractive index n2, an edge of which along said z-axis is in direct contact with at least a second block of a second dielectric material with a second width W2 along said x-axis, said height H along said z-axis and a third refractive index n3, said first, second and third refractive indexes n1, n2 n3 are different from each other such that n1<n3<n2. The first block and the second block have a trapezoidal cross-section in said vertical xz plane. The first and second blocks have two sidewalls and a top surface running parallel to a top surface of the substrate, and the trapezoidal cross-section defines base angles. The plurality of grating unit cells provides non symmetrical response for positive first diffraction order and negative first diffraction order based on nanojets hot spot positions defined by values of said parameters H, n1, n3, n2. and said base angles, from electromagnetic waves, which are normally incident on said diffraction grating and come from a side opposite to said substrate in a vertical xz plane with a free-space wavelength λ, called an operating wavelength, said free-space wavelength λ belonging to the visible light domain, and wherein said nanojets being generated at edges between dielectric materials with different refractive indexes.