Optical Waveguide Grating Transition Areas for Nanoimprint Defect Reduction
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Solution Overview
Problem
The fabrication of waveguides for head-worn displays using a nanoimprint process often results in deformities and air bubbles in the grating structures due to the soft working stamp being damaged or sticking to the master stamp, which impairs the functionality of the waveguide.
Innovation Solution
Incorporating grating transition areas with modulated parameters adjacent to the main grating areas in the waveguide design, which helps in reducing the likelihood of damage to the soft-working stamp and minimizes the introduction of air bubbles during the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If grating structures with certain characteristics are fabricated using a soft working stamp in a nanoimprint process, then the waveguide can be manufactured, but the soft working stamp is damaged or sticks to the master stamp, introducing deformities and air bubbles in the grating structures
Solution Approach 1:
The patent applies preliminary action by modifying the master stamp design before the nanoimprint process. Specifically, the master stamp includes a support structure that protrudes into the cavity and a release structure with a slope angle of 10-45 degrees. These preliminary design features prevent stamp damage and air bubble formation during subsequent fabrication operations, eliminating the need for corrective actions after deformities occur.
Solution Approach 2:
The patent introduces an intermediary mechanism through the release structure on the master stamp. The sloped surface acts as a mediator between the soft working stamp and the cavity, enabling controlled separation that prevents the stamp from sticking. This intermediary geometric feature facilitates smooth material ejection and stamp removal without direct adhesive interference, thereby preventing deformities and air bubbles.
2Productivity
If the soft working stamp is removed from the master stamp after imprinting, then the grating structures can be formed on the waveguide, but the soft working stamp is damaged, increasing the likelihood of deformities
Solution Approach 1:
The release structure with its sloped surface serves as an intermediary mechanism that mediates the separation between the soft working stamp and the master stamp. This geometric intermediary allows the stamp to be removed smoothly without sudden stress or adhesion forces that would cause damage, thereby maintaining stamp integrity while enabling continuous production.
Solution Approach 2:
The support structure protruding into the cavity provides beforehand cushioning by distributing the mechanical stress during stamp removal. This preliminary structural support prevents concentrated forces that would damage the soft working stamp, cushioning the separation process and maintaining stamp reliability for repeated use in productive fabrication cycles.
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 use of grating transition areas in waveguides reduces the likelihood of deformities and air bubbles in the grating structures, thereby enhancing the functionality and reliability of the waveguide by ensuring that the grating structures operate as intended.
Implementation Method 1
some waveguides include an incoupler and an outcoupler each having sets of grating structures configured to direct light based on various parameters
Implementation Method 2
the light propagates through the waveguide toward the outcoupler
Data Source
AI summary
A waveguide includes a set of grating structures forming a component on the surface of the waveguide. The set of grating structures is configured to direct light received at the component based on a parameter of one or more grating structures of the set of grating structures. Further, the waveguide includes a first transition area disposed adjacent to a first side of the component wherein the parameter is modulated across the grating structures of the first transition area. Additionally, the waveguide includes a second transition area disposed adjacent to a second, opposite side of the component wherein the parameter is also modulated across the grating structures of the second transition area.