Tapered Core Light Waveguide for Low-Loss Optical Coupling
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Solution Overview
Problem
Existing light waveguide technologies face challenges in manufacturing core layers with varying cross-section sizes between the light input and output sides, limiting the ability to easily form core layers with sizes in the range of 1 μm×1 μm to 3 μm×3 μm due to thickness limitations of resin films.
Innovation Solution
A light waveguide structure is developed with a first cladding layer, a groove formed in the cladding layer, and a core layer embedded within the groove, where the width and thickness of one end of the core layer are larger than the other end, allowing for adjustable cross-section sizes by varying the groove dimensions, enabling easier manufacturing of light waveguides with differing input and output side sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to form core layers from photosensitive resin films, then the manufacturing process is simple, but the cross section size cannot be reduced below the resin film thickness limitation of about 10 μm
Solution Approach 1:
The manufacturing process is divided into two independent stages: first forming the groove structure in the lower cladding layer, then separately forming the core layer within the groove. This segmentation allows the core layer dimensions to be determined by the groove structure rather than being constrained by the thickness of a single photosensitive resin film, enabling precise control of small cross section sizes (1-3 μm) while maintaining manufacturing simplicity.
Solution Approach 2:
The invention transitions from a single-layer photosensitive resin film approach to a multi-layer structure with a groove in the lower cladding layer. By utilizing the vertical dimension to create the groove and then filling it with core layer material, the patent achieves precise control of core layer cross section size independent of the lower cladding layer thickness, overcoming the 10 μm thickness limitation.
2Reliability
If the core layer cross section size is reduced to 1 μm×1 μm to 3 μm×3 μm, then optical coupling with small core diameter fibers is improved, but conventional photolithography cannot achieve this size due to resin film thickness limitations
Solution Approach 1:
By separating the groove formation process from the core layer formation process, the patent enables independent optimization of each step. The groove can be formed with precise dimensions using conventional lithography, and the core layer can be formed to match the groove, achieving small cross section sizes (1-3 μm) that enable efficient optical coupling with small core diameter fibers.
Solution Approach 2:
The groove structure acts as an intermediary that mediates between the lower cladding layer and the core layer. It provides a pre-formed mold that defines the core layer dimensions, allowing the core layer to achieve small cross section sizes without being constrained by the thickness of the photosensitive resin film used to form it directly.
3Adaptability or versatility
If the core layer has uniform cross section size, then the manufacturing process is simple, but it cannot meet the demand for different cross section sizes at light input and output sides
Solution Approach 1:
The groove structure is designed with local quality variations, where the width and depth can differ at different positions along the light propagation direction. This allows the core layer to have different cross section sizes at the input and output sides by simply varying the groove dimensions locally, without increasing overall structural complexity or requiring additional manufacturing steps.
Data Source
AI summary
A light waveguide includes a first cladding layer, a groove formed in the first cladding layer, a core layer embedded in the groove, and a second cladding layer formed on the first cladding layer and the core layer. A width and thickness of one end of the core layer are larger than a width and thickness of the other end of the core layer.