Optical Waveguide Control Electrode Impedance Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical waveguide devices experience electrical discontinuity and deteriorated characteristics due to mismatched electrode sizes and distances between the modulation substrate and the relay or termination substrates, leading to increased manufacturing costs and impedance mismatching.
Innovation Solution
An optical waveguide device module design where the control electrode has ground electrodes with varying distances, with the distance between ground electrodes being larger at the input/output ends and smaller away from them, and the connection substrate has interconnections with distances smaller than the optical waveguide device's ground interconnections, using a common connection substrate for different types of optical waveguide devices, and forming connections via wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode sizes or distances between ground electrodes of modulation substrate and relay substrate are designed to be equal to each other to improve frequency characteristic, then discontinuity of connection portions is reduced, but manufacturing cost increases due to requiring custom connection substrates for each device type
Solution Approach 1:
The connection substrate is designed with a standardized electrode configuration (signal electrode and ground electrode with specific width and distance ratios) that can be universally applied to different types of optical waveguide devices. This universal design allows the same connection substrate to interface with various modulation substrates without requiring custom designs for each device type, thereby reducing manufacturing costs while maintaining good frequency characteristics through controlled impedance matching.
2Speed
If materials with lower dielectric constant than modulation substrate are used in relay substrate to achieve higher frequency and smaller connection portions, then bandwidth is improved, but impedance mismatching occurs due to different signal line widths between substrates
Solution Approach 1:
The invention controls the electrical characteristics by adjusting geometric parameters of the electrodes rather than relying solely on material properties. Specifically, the width and distance ratios of the signal electrode and ground electrode are optimized to achieve proper impedance matching (50Ω) despite using materials with different dielectric constants. This parameter-based approach allows the use of low-dielectric-constant materials for high-frequency performance while maintaining electrical continuity through controlled geometry.
3Reliability
If the width of signal electrode and distance between ground electrodes are made different between optical waveguide device and relay substrate to match impedance, then electrical connection continuity is improved, but manufacturing complexity increases
Solution Approach 1:
The connection substrate employs a localized electrode design where the signal electrode and ground electrode have specific width and distance ratios optimized for impedance matching at the connection interface. This local optimization is concentrated at the critical connection portions between substrates, while other areas can use simpler configurations. The design focuses the complexity only where needed for electrical continuity, rather than requiring complex configurations throughout the entire structure.
Data Source
AI summary
An optical waveguide device module has an optical waveguide device including an optical waveguide formed in a substrate, and a control electrode for controlling light; and a connection substrate including an interconnection, provided to the outside of the waveguide device, electrically connected to the control electrode. The control electrode includes ground electrodes that sandwich a signal electrode. The connection substrate has ground lines that sandwich a signal line. A width of the signal electrode in an input or output end is smaller than a width of the signal line on the waveguide device side. A distance between inner edges of the ground electrodes closest to the signal electrode, measured at an input or output end of the control electrode, is larger than a distance between inner edges of the ground lines closest to the signal line on the waveguide device side of the connection substrate.