Optical Waveguide Manufacturing via Wet-Etched Crystal Planes
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Solution Overview
Problem
Existing methods for manufacturing optical waveguides face challenges in forming precise and minute slant surfaces for mirrors, leading to light propagation losses and positioning inaccuracies, as well as protrusions that require raised mounting pads for electronic components.
Innovation Solution
A method involving wet-etching on a crystalline substrate to form grooves with accurately inclined crystal planes, followed by deposition of metallic reflection films to create mirrors, and filling these grooves with a core material, while using clad layers to cover the core, allowing for precise and minute optical waveguide fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If slant surfaces are formed by dicing, then the manufacturing process is simple, but the surface roughness becomes large causing light propagation losses
Solution Approach 1:
The patent replaces the mechanical dicing process with a photolithographic process to form slant surfaces. The photolithographic process uses light patterns to define the slant surfaces, avoiding the mechanical contact and high surface roughness associated with dicing, thereby reducing light propagation losses while maintaining manufacturing feasibility
Solution Approach 2:
The patent changes the manufacturing parameters by using photolithography instead of dicing, controlling the slant surface formation through optical exposure parameters such as light intensity, exposure time, and mask design, which enables precise control of surface quality and angle without mechanical roughness
2Manufacturing precision
If slant surfaces are formed by photolithographic process, then the surface quality is improved, but the angles cannot be accurately formed at 45 degrees
Solution Approach 1:
The patent introduces a specific asymmetric mask design with predetermined angles that are not symmetric at 45 degrees. The mask pattern is specifically designed to create the required slant surface angles through photolithographic exposure, allowing precise angular control by adjusting the mask geometry rather than relying on symmetric 45-degree configurations
Solution Approach 2:
The patent performs preliminary action by pre-designing the mask pattern with the exact angular requirements before the photolithographic process. The mask is prepared in advance with predetermined angles that will directly transfer the desired slant surface geometry to the substrate, ensuring angle accuracy is built into the process rather than achieved through post-processing adjustment
3Adaptability or versatility
If optical waveguide is manufactured on dummy board and transferred, then the manufacturing flexibility is improved, but the positioning precision worsens
Solution Approach 1:
The patent merges the optical waveguide manufacturing process with the circuit board fabrication process by forming the optical waveguide directly on the circuit board substrate. This integration eliminates the separate dummy board manufacturing and transfer process, thereby maintaining manufacturing flexibility while achieving superior positioning precision through direct formation at the final location
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 enables the production of optical waveguides with low surface roughness and accurate angle formation, reducing light propagation losses and improving positioning precision, eliminating the need for raised mounting pads.
Implementation Method 1
the light vertically emitted from the light emitting element toward the circuit board is reflected 90 degrees so as to become horizontal to the circuit board, by a mirror portion whose light travel direction has an angle of 45 degrees
Implementation Method 2
a material of relatively high refractive index is used for the core 112, whereas a material of relatively low refractive index is used for the first clad layer 110 and the second clad layer 114
Data Source
AI summary
A method for manufacturing an optical waveguide which includes a core configured to transmit an optical signal, and a mirror portion configured to reflect the optical signal, the method includes: forming a mask layer patterned in a predetermined shape, on a first crystal plane of a substrate made of a crystalline material; etching the first crystal plane by a wet-etching using the mask layer to form a groove having a plurality of crystal planes; providing a metallic reflection film on at least one of the plurality of crystal planes to form the mirror portion; and providing the groove with a core material to form the core.