Optical Waveguide Substrate Curved End Face
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Solution Overview
Problem
In the production of optical integrated circuits, the high refractive index of optical waveguide cores leads to significant reflection at the end faces, which complicates the alignment and processing of multiple waveguides, necessitating anti-reflection coatings that are cumbersome and restrictive for complex circuit designs.
Innovation Solution
An optical waveguide substrate with an end face featuring an etched surface and unevenness resulting from differences in etching rates of multi-layered optical material films, mimicking a Moth-Eye structure to prevent reflection without the need for anti-reflection coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If anti-reflection coatings are formed on the end faces of optical waveguides to prevent reflection, then reflection is reduced, but the alignment and processing complexity increases significantly
Solution Approach 1:
The patent applies the curvature principle by forming a curved surface at the end face of the optical waveguide through etching. This curved surface gradually transitions from the flat end face into the waveguide core, creating a tapered profile that reduces Fresnel reflection. The curvature eliminates the need for anti-reflection coatings and complex alignment procedures, directly resolving the technical contradiction between reducing reflection and maintaining processing simplicity.
2Adaptability or versatility
If the end portions of multiple optical waveguides are positioned non-parallel to allow flexible circuit design, then design freedom increases, but the end faces become misaligned requiring polygonal polishing and multiple anti-reflection coatings
Solution Approach 1:
The curved surface structure is applied universally to all waveguide end faces regardless of their orientation or alignment. This approach allows multiple waveguides to be positioned at different angles and locations without requiring precise parallel alignment or complex polygonal polishing. The curvature provides a universal solution that maintains low reflection across all orientations, enabling flexible circuit design while simplifying manufacturing.
Solution Approach 2:
The patent changes the geometric parameter of the end face from flat to curved through controlled etching. This parameter change transforms the optical properties of the end face, reducing reflection without requiring additional coatings or complex alignment. The curved profile is achieved by modifying the etching conditions to create a gradual transition zone, which eliminates the need for multiple processing steps.
3Ease of manufacture
If a flat end face is used for the optical waveguide, then manufacturing is simpler, but reflection at the end face reduces transmission efficiency
Solution Approach 1:
The patent introduces a curved surface at the end face through etching, which reduces Fresnel reflection and improves transmission efficiency. While this adds a processing step, the curvature is formed through controlled etching conditions rather than complex multi-step processes. The energy loss reduction from eliminating reflection outweighs the moderate increase in manufacturing complexity, achieving a favorable balance between the two parameters.
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 approach effectively reduces reflection at the end faces of optical waveguides, allowing for more flexible and efficient alignment of waveguides in complex optical circuits, improving the design and manufacturing process while maintaining high transmission efficiency.
Implementation Method 1
the end face comprises an unevenness corresponding with a difference of etching rates of said optical material films... the unevenness functions as a kind of a Moth-Eye structure to prevent the reflection at the end faces
Data Source
AI summary
An optical waveguide substrate 1 includes an optical waveguide 9 composed of a multi-layered film 4 of a plurality of optical material films 5, 6 and having end faces onto which a light is made incident or from which the light is emitted. The end face is an etched surface, and it is provided, on the end face, an unevenness 7 corresponding to a difference of etching rates of the optical material films.