Waveguide Grating Slant Control by Substrate Rotation Etching
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Solution Overview
Problem
Forming gratings with different slant angles on a substrate or successive substrates is challenging due to the complexity of reconfiguring angled etch systems, which leads to non-uniform depths and increased fabrication time and costs.
Innovation Solution
A method involving substrate rotation on a platen to control slant angles using ion beam etching, employing equations to select rotation angles without reconfiguring the ion beam chamber, thus allowing a single etch system to form gratings with varying slant angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the optimized angle is changed to form gratings with different slant angles, then the slant angle variety is improved, but the device complexity and reconfiguration time increase
Solution Approach 1:
The platen is made rotatable about the ion beam axis, allowing dynamic adjustment of the substrate orientation during the etching process. This enables the formation of gratings with different slant angles by rotating the platen to different angles φ, eliminating the need to reconfigure the ion beam chamber hardware for each slant angle variation.
2Adaptability or versatility
If the tilt angle is adjusted to modify the ion beam angle, then the slant angle is improved, but the grating depth uniformity deteriorates
Solution Approach 1:
Instead of tilting the platen to change the ion beam angle, the invention rotates the platen about the ion beam axis. This dynamic rotation allows precise control of the slant angle while maintaining the ion beam's perpendicular incidence to the substrate surface, ensuring uniform etching depth across the substrate.
3Adaptability or versatility
If multiple angled etch systems are used to form gratings with different slant angles, then the slant angle variety is improved, but the fabrication time and cost increase
Solution Approach 1:
The platen is designed to perform multiple functions: it can be tilted to adjust the ion beam angle for optimal etching, and it can be rotated about the ion beam axis to form gratings with different slant angles. This multi-functionality allows a single angled etch system to replace multiple specialized systems, reducing fabrication time and cost.
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
Enables efficient fabrication of waveguide combiners with gratings of different slant angles without reconfiguring the etch system, reducing fabrication time and costs while ensuring uniformity.
Implementation Method 1
directing an ion beam towards the substrate having a grating material disposed thereon, the ion beam configured to contact the grating material at ion beam angle θ relative to a surface normal of the substrate
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A waveguide combiner including a first portion of one or more first gratings disposed on a substrate. Each first grating of the first portion including a first grating vector; and a first slant angle. The waveguide combiner including a second portion of one or more second gratings disposed on the substrate. Each second grating of the second portion comprising a second grating vector, the second grating vector different than the first grating vector; and a second slant angle, the second slant angle different than the first slant angle