Optical Waveguide Pedestal Block Formation via Thermal Masking
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Solution Overview
Problem
Existing optical waveguide devices face challenges in achieving high accuracy in pedestal block formation during high-temperature heat treatment, which can lead to inaccuracies in optical coupling and increased thermal stress.
Innovation Solution
The optical waveguide device employs a thin film mask on the upper cladding layer, allowing for high-temperature processing of the lower cladding and core layers without affecting the mask, and uses low-melting silica films with dopants like boron or phosphorous for precise pedestal block formation, enabling accurate height matching and reduced thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-temperature heat treatment is applied to form the upper cladding layer, then the optical waveguide structure is completed, but the pedestal block formation accuracy deteriorates due to thermal stress and deformation
Solution Approach 1:
The patent divides the cladding layer into two separate layers: a lower cladding layer formed at low temperature (400-600°C) and an upper cladding layer formed at high temperature (800-900°C). This segmentation allows the lower cladding layer to serve as a stable base for the pedestal block while the upper cladding layer provides the necessary optical waveguide functionality, resolving the contradiction between high-temperature processing and pedestal block accuracy.
Solution Approach 2:
The lower cladding layer is formed first as a preliminary structure before forming the upper cladding layer. This preliminary lower cladding layer establishes the accurate pedestal block height and provides a thermally stable base that prevents deformation during subsequent high-temperature processing of the upper cladding layer.
2Ease of operation
If the pedestal block is formed using conventional methods, then the optical component mounting is enabled, but the optical coupling accuracy deteriorates due to height mismatch
Solution Approach 1:
The patent controls the thickness parameter of the lower cladding layer (50-200 nm) to precisely adjust the pedestal block height. By changing this thickness parameter, the vertical position of the optical component is accurately controlled, enabling precise optical coupling with the waveguide core layer while maintaining ease of mounting operations.
3Device complexity
If a single cladding layer is used, then the manufacturing process is simplified, but the thermal stress increases causing deformation
Solution Approach 1:
The patent segments the cladding layer into two distinct layers with different formation temperatures and material properties. The lower cladding layer (400-600°C) and upper cladding layer (800-900°C) each experience thermal stress only during their respective formation processes, distributing the thermal stress over time and preventing cumulative deformation that would occur with a single high-temperature layer.
Solution Approach 2:
Different regions of the cladding structure have different thermal histories and material properties. The lower cladding layer is optimized for thermal stability and pedestal block support, while the upper cladding layer is optimized for optical waveguide performance. This local differentiation of quality allows each layer to perform its specific function without excessive thermal stress.
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 allows for high-accuracy pedestal block formation even at high temperatures, improving optical coupling precision and reducing thermal stress, thereby enhancing the flexibility and accuracy of optical waveguide design.
Implementation Method 1
the lower cladding layer and the core layer are heated at a high temperature
Implementation Method 2
a mask consisting of a thin film provided on the upper cladding layer, allowing for high-temperature processing of the lower cladding and core layers without affecting the mask
Implementation Method 3
uses low-melting silica films with dopants like boron or phosphorous for precise pedestal block formation
Data Source
Figure 1
Figure 2A~2I
Figure 3
AI summary
An optical waveguide device which includes an optical waveguide part and aphotonic device mounting part is provided. A mask to form a pedestal block on which a light emitting device is mounted is patterned after high-temperature annealing. Thus, there is no influence on the mask, even if the device undergoes the heat treatment at a high temperature during the manufacturing process. This enables formation of the pedestal block with high accuracy. Therefore, it is possible to achieve an optical coupling with high accuracy in mounting a light emitting device on the pedestal block.