Multi-Channel Receiver Optical Sub-Assembly Passive Alignment
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Solution Overview
Problem
Conventional receiver optical sub-assemblies face challenges in achieving high frequency characteristics and cost-effectiveness due to complex alignment processes and impedance mismatch issues, particularly at data rates of 25 Gbps or more, which complicates mass production and increases costs.
Innovation Solution
A multi-channel receiver optical sub-assembly is designed using passive alignment and a manufacturing method that includes forming an inclined surface on the PLC chip, integrating a lens within the SI-PD, and using alignment marks for precise bonding, eliminating the need for bulky glass lenses and reducing the complexity of active alignment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active alignment and butt-coupling are performed between the PLC chip and the SI-PD with a bulky glass lens, then optical coupling efficiency is enhanced, but the length of the light receiving part is increased and the manufacturing process becomes complicated requiring more time
Solution Approach 1:
The patent removes the bulky glass lens from the optical coupling structure, replacing it with a direct coupling mechanism between the PLC chip and SI-PD. This extraction of the lens eliminates the need for complex alignment procedures while maintaining coupling efficiency through precise passive alignment features built into the carrier structure.
Solution Approach 2:
The patent incorporates pre-formed alignment marks and alignment structures on the carrier and PLC chip before the actual coupling process. These preliminary alignment features enable passive alignment without requiring time-consuming active alignment procedures during assembly, thus simplifying the manufacturing process while ensuring accurate optical coupling.
2Ease of manufacture
If the SI-PD, glass lens, and PLC chip are discretely passively aligned with each other, then assembly is simplified, but misalignment of about 10 um occurs for the narrow light receiving part resulting in remarkably lowered optical coupling efficiency
Solution Approach 1:
The patent introduces an intermediary alignment mechanism consisting of alignment marks and alignment structures on the carrier that mediate between the SI-PD and PLC chip. This intermediary system enables passive alignment to achieve sub-micron precision, eliminating misalignment issues while maintaining assembly simplicity through a single bonding step.
3Adaptability or versatility
If a high frequency transmission line is bent at 90° between the SI-PD and TIA array, then the conventional structure is maintained, but severe impedance mismatch occurs and high frequency signal is radiated deteriorating receiver performance
Solution Approach 1:
The patent replaces the 90° bent transmission line with a curved or angled transmission line that maintains gradual transitions. This curvature modification eliminates severe impedance mismatches and signal radiation while preserving the conventional structural layout, thereby maintaining structural compatibility without compromising high frequency performance.
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 enhances optical coupling efficiency, minimizes optical coupling loss, and maintains high frequency characteristics, enabling the production of receiver optical sub-assemblies in a smaller size at a lower cost while reducing manufacturing complexity and radiation losses.
Implementation Method 1
an inclined surface which is formed on the other side of the PLC chip
Data Source
AI summary
Provided herein are a multi-channel receiver optical sub-assembly and a manufacturing method thereof. The multi-channel receiver optical sub-assembly includes a PLC chip having a first side into which an optical signal is received and a second side from which the received signal is outputted, with an inclined surface formed on the second side of the PLC chip at a preset angle, a PD carrier bonded onto the PLC chip and made of a glass material, and an SI-PD bonded onto the PD carrier, a lens being integrated therein. The PLC chip, the PD carrier, and the SI-PD are passively aligned by at least one alignment mark and then are bonded.