Optical Module Bridge Substrate Signal Integrity
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Solution Overview
Problem
Existing optical modules face signal quality degradation due to parasitic components inherent in bonding wires when connecting transmission lines with electro-absorption modulators, which degrades modulation signal quality at high frequencies.
Innovation Solution
An optical module design that uses a semiconductor optical device, a wiring substrate, and a bridge substrate to provide a modulation signal, where the signal line of the bridge substrate is connected directly to the semiconductor optical device's pad, bypassing bonding wires and utilizing co-planar lines with ground metals to suppress capacitive coupling and maintain impedance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bonding wires are used to connect transmission lines with the electro-absorption modulator, then the device complexity is reduced and ease of manufacture is improved, but parasitic components are introduced that degrade modulation signal quality at high frequencies
Solution Approach 1:
The patent extracts and eliminates the bonding wire connection method from the system. Instead of using bonding wires to connect the transmission line to the electro-absorption modulator, the invention directly integrates the transmission line with the modulator electrode, removing the source of parasitic inductance and capacitance that degrade high-frequency signal quality.
Solution Approach 2:
The patent introduces a ground metal layer as an intermediary element between the signal line and the electrode. This ground metal serves as a reference potential that suppresses capacitive coupling and maintains impedance characteristics, enabling direct connection without bonding wires while preserving signal integrity at high frequencies.
2Adaptability or versatility
If transmission line length is extended to reach the electro-absorption modulator, then the device layout flexibility is improved, but signal quality degradation increases due to parasitic components and impedance mismatching
Solution Approach 1:
The patent replaces the traditional mechanical bonding wire connection with a direct integrated transmission line structure. The transmission line is formed as part of the substrate architecture with embedded ground metals, eliminating the need for separate connection elements and enabling optimized signal paths that maintain impedance control regardless of layout variations.
Solution Approach 2:
The patent changes the electrical parameters of the transmission line by incorporating ground metals at specific positions. This creates a controlled impedance environment that maintains signal quality even when transmission line length or layout varies, allowing greater design flexibility without compromising performance.
3Reliability
If ground metal is added to surround the signal line on the bridge substrate, then impedance control and signal quality are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the ground metal layer with the substrate structure itself. Rather than adding ground metals as separate components, they are integrated into the bridge substrate fabrication process, forming a unified structure that provides impedance control without requiring additional assembly steps or complex multi-layer constructions.
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 suppresses impedance mismatching and degradation of the modulation signal, ensuring high-frequency signal quality by eliminating parasitic components and maintaining regular impedance, thus enhancing the performance of the optical module.
Implementation Method 1
suppress capacitive coupling and maintain impedance characteristics
Data Source
AI summary
An optical module including a source assembly is disclosed. The source assembly provides a semiconductor optical device, a wiring substrate, and a bridge substrate. The semiconductor optical device includes an electrode and a pad that receives a driving signal therethrough. The wiring substrate, which is arranged side by side with respect to the semiconductor optical device, provides a signal line and a ground line surrounding the signal line. The bridge substrate includes a signal line and a ground line surrounding the signal line. A feature of the optical module is that the bridge substrate is placed on the semiconductor optical device and the wiring substrate such that a transmission line thereof faces the semiconductor optical device and the wiring substrate, and one end of the signal line thereof is connected with the pad of the semiconductor optical device through a post, and another end of the signal line thereof is connected with an end of the signal line in the wiring substrate through another post.