Optical Waveguide Fabrication via Photomask Exposure
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Solution Overview
Problem
Current methods for fabricating optical waveguides, such as geometric, surface relief, and volumetric holographic grating waveguides, are complex and costly, particularly due to the need for multiple processes like deposition and etching, and high fabrication costs associated with volumetric holographic grating waveguides.
Innovation Solution
A method involving a photomask with light blocking structures is used to form a light curing resin layer with a periodically varying refractive index through a single exposure process, replacing deposition and etching processes and improving the performance of surface relief grating waveguides with low-cost and simple fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple processes like deposition and etching are used to fabricate surface relief grating waveguides, then the imaging quality and performance are improved, but the fabrication complexity and cost increase
Solution Approach 1:
The patent combines multiple separate fabrication processes (deposition and etching) into a single photolithography-based exposure process. By using a photomask with light blocking structures and exposing a light curing resin layer, the invention creates periodic refractive index variations directly without needing separate deposition and etching steps, thus reducing fabrication complexity while maintaining imaging quality
Solution Approach 2:
The invention replaces mechanical/physical processes (deposition and etching) with an optical process (photolithography exposure). Instead of mechanically depositing materials or chemically etching patterns, the patent uses light exposure through a photomask to directly form the periodic structure in the resin layer, simplifying the fabrication workflow
2Reliability
If volumetric holographic grating waveguides are used to achieve periodic refractive index differences, then the optical performance is improved, but the fabrication cost increases due to requiring optical exposure systems
Solution Approach 1:
The patent uses a disposable photomask with light blocking structures that can be easily manufactured and replaced, eliminating the need for expensive optical exposure systems. The photomask serves as a simple, low-cost template that defines the periodic pattern through light blocking, providing an economical alternative to sophisticated volumetric holographic systems
Solution Approach 2:
The invention changes the approach to creating periodic refractive index differences from volumetric holographic methods to surface-level photolithography exposure. By controlling the exposure parameters (light intensity, exposure time, photomask design) rather than using complex volumetric holographic systems, the patent achieves similar optical performance with lower fabrication costs
3Reliability
If geometric optical waveguides stack and glue reflectors arranged into an array with dozens of layers, then the light guiding performance is improved, but the fabrication complexity and time increase
Solution Approach 1:
The patent merges the functions of multiple reflector layers into a single photolithography exposure process. Instead of stacking and gluing individual reflector layers, the invention uses a photomask to expose a resin layer that forms the periodic structure in one step, dramatically reducing fabrication time and complexity while maintaining light guiding performance
Solution Approach 2:
The patent performs the pattern formation action in advance during the photolithography exposure process, before any assembly or gluing steps would be needed. By pre-forming the periodic refractive index structure through light exposure, the invention eliminates subsequent assembly operations and improves fabrication efficiency
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
This method simplifies the fabrication of optical waveguides by using a single exposure process to create a light curing resin layer with a periodically varying refractive index, reducing costs and complexity while enhancing performance.
Implementation Method 1
The light blocking structure includes oxides that absorb the ultraviolet light
Implementation Method 2
ultraviolet light scattering particles
Implementation Method 3
irradiating and curing the first light curing resin layer to have a first curing level and a corresponding first refractive index
Data Source
AI summary
Methods for fabricating an optical waveguide and a display device and a photomask used therein is provided. Firstly, a photomask is provided, wherein the photomask has light blocking structures regularly distributed. A first light curing resin layer is formed on a first transparent substrate. Next, the photomask is placed on the first light curing resin layer. The first light curing resin layer is irradiated and cured with incident light through the photomask and the light blocking structures to have a first curing level and a first refractive index. The first curing level and the first refractive index, corresponding to each other, are periodically distributed. Finally, the photomask is removed from the first light curing resin layer to form an optical waveguide with the first light curing resin layer having the first curing level that is periodically distributed and the first transparent substrate.