Fanout Diffractive Optical Element Asymmetric Waist Design
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Solution Overview
Problem
Existing diffractive optical elements lack efficient designs for manipulating monochromatic radiation into multiple diffraction orders with high diffraction efficiency and symmetry, which is crucial for applications like optical computing and data transmission systems.
Innovation Solution
A fanout diffractive optical element with a discrete periodic surface relief structure having a 2-dimensional (x,y) shape, comprising a first lobe and a second lobe separated by a waist region, where the waist region has a width less than the lobes, and featuring an inversion center and asymmetry about any normal plane, achieving high diffraction efficiency and symmetry about a C2 rotational axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional diffractive optical elements are used, then light can be diffracted into multiple orders, but the diffraction efficiency is insufficient and symmetry control is poor
Solution Approach 1:
The patent applies asymmetry by designing a surface relief structure that lacks symmetry about any plane normal to the structure, while maintaining inversion center symmetry. This asymmetric design about normal planes is crucial for achieving high diffraction efficiency into specific diffraction orders while suppressing unwanted orders, directly resolving the technical contradiction between efficiency and complexity.
Solution Approach 2:
The patent transitions from conventional two-dimensional grating structures to a three-dimensional surface relief structure with controlled height profiles. The height of the relief structure is optimized to enhance diffraction efficiency into specific orders, representing a dimensional addition that resolves the efficiency-complexity contradiction by utilizing the vertical dimension for efficiency enhancement without proportionally increasing horizontal complexity.
2Ease of manufacture
If symmetric surface relief structures are used, then manufacturing is simplified, but the ability to control diffraction orders with high efficiency is reduced
Solution Approach 1:
The patent specifies that the surface relief structure lacks symmetry about any plane normal to the structure, which provides precise control over diffraction order distribution. This asymmetric design enables high manufacturing precision in terms of diffraction control while remaining manufacturable through standard lithography and etching processes, resolving the contradiction between ease of manufacture and precision of diffraction control.
Solution Approach 2:
The patent optimizes specific parameters of the surface relief structure including the height (at least 0.5 μm), the waist region width ratio (less than 0.7), and the top-to-base area ratio (at least 0.80). These parameter optimizations enable precise control of diffraction efficiency while maintaining compatibility with standard manufacturing processes, resolving the contradiction between manufacturing ease and diffraction control precision.
3Ease of manufacture
If the waist region width is increased, then the structure is easier to manufacture, but the diffraction efficiency into specific orders decreases
Solution Approach 1:
The patent specifies that the waist region width should be less than 0.7 times the length of the surface relief structure, and preferably less than 0.6 times. This parameter optimization balances manufacturability with high diffraction efficiency, resolving the contradiction by defining a specific range that satisfies both manufacturing constraints and optical performance requirements.
Solution Approach 2:
The patent employs a curved height profile for the surface relief structure with a waist region that tapers the width. This curved geometry concentrates the diffracting surface area in specific regions, enhancing efficiency into targeted diffraction orders while maintaining overall structural manufacturability, thus resolving the efficiency-manufacturability contradiction.
4Loss of energy
If the surface relief height is increased, then diffraction efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies that the surface relief structure should have a height of at least 0.5 μm, and preferably at least 0.9 μm. These parameter specifications optimize diffraction efficiency while remaining within the capabilities of standard semiconductor fabrication processes, resolving the contradiction between efficiency improvement and manufacturing precision requirements.
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 design achieves a diffraction efficiency of at least 70% and efficiently splits light into multiple diffraction orders, suitable for applications in optical computing and data transmission systems, with the ability to produce a two-dimensional array of diffraction orders.
Implementation Method 1
Diffractive optical elements are used to manipulate light in a variety of applications. Diffractive optical elements, for example, are commonly found in optical analytical instruments for separating polychromatic radiation into one or more monochromatic components.
Data Source
AI summary
A fanout diffractive optical element having a discrete periodic surface relief structure having a 2-dimensional (x,y) shape is described. The surface relief structure can include a first lobe and a second lobe separated by a waist region having a width less than the first lobe and the second lobe. The 2-dimensional (x,y) shape of surface relief structure can have an inversion center and can lack symmetry about any plane that is normal to the surface relief structure. Also described are apparatuses having a fanout diffractive optical element and methods of producing a plurality of light diffracting orders using a fanout diffractive optical element.