Optical Module Surface-Leveling for Alignment Precision
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Solution Overview
Problem
Conventional optical modules face challenges in maintaining precise optical alignment and reducing parasitic capacitance due to the limited positional tolerance and potential misalignment during the fixation of semiconductor photodiodes with narrowed sensitive areas, leading to inclination of the optically sensitive surface relative to the optical axis.
Innovation Solution
The optical module design aligns the optically sensitive surface of the semiconductor device within a virtual plane extending from the end surface of the primary assembly, using a combination of precise alignment mechanisms such as YAG laser welding and adhesive resin, and a specific arrangement of lens holders and J-sleeves to fix the receiver unit, ensuring the optically sensitive surface remains parallel to the end surface, thereby minimizing misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optically sensitive surface level is not aligned with the end surface of the primary assembly, then the fixation process is simpler, but positional deviations occur leading to misalignment
Solution Approach 1:
The optically sensitive surface of the semiconductor optical device is pre-aligned to be level with the end surface of the primary assembly before fixation. This preliminary alignment ensures that subsequent fixation operations maintain precise optical alignment without requiring complex real-time adjustment mechanisms during the assembly process.
Solution Approach 2:
The patent replaces complex mechanical alignment adjustment mechanisms with a simplified fixation structure that relies on the pre-established level alignment between the optically sensitive surface and the end surface. This substitution eliminates the need for intricate mechanical adjustment systems while maintaining high alignment precision.
2Reliability
If the optically sensitive area is narrowed to reduce parasitic capacitance, then the junction capacitance decreases, but the positional tolerance for optical alignment becomes more limited
Solution Approach 1:
The patent applies preliminary anti-action by pre-aligning the optically sensitive surface to the end surface of the primary assembly before fixation. This proactive alignment compensates for the reduced positional tolerance caused by the narrowed sensitive area, preventing misalignment issues that would otherwise arise from the stricter tolerance requirements.
Solution Approach 2:
By establishing the level alignment between the optically sensitive surface and the end surface before the fixation process, the patent creates a robust baseline that accommodates the reduced positional tolerance. This preliminary action ensures that even with the narrower sensitive area, the optical alignment remains within acceptable tolerances.
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 design effectively restricts positional deviations of the optically sensitive surface, maintaining precise optical alignment and reducing junction capacitance, even with narrower sensitive areas, enhancing the reliability and performance of high-speed optical communication systems.
Implementation Method 1
YAG laser welding
Implementation Method 2
adhesive resin
Data Source
AI summary
A bi-directional optical module that provides an Rx unit and a Tx unit, where optical axes are perpendicular to each other, is disclosed. The optical module provides a housing that installs a WDM filter therein and assembles the coupling unit in a surface through the front alignment unit, the Tx unit in another surface opposite to the former surface, and the Rx unit in still another surface connecting the former two surfaces through the rear alignment unit. The axes of the Tx unit and the coupling unit are in parallel to each other, but the axis of the Rx unit is in perpendicular to the former two axes. The Rx unit installs a photodiode (PD) with an optically sensitive surface leveled with the surface of the rear alignment unit to which the Rx unit is attached.