Optical Modulator Polymer Edge Placement for Impedance Matching
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Solution Overview
Problem
Optical modulators on silicon substrates face challenges in size reduction due to high power consumption and impedance mismatching issues, particularly when using polymer waveguides, which require long metal wires for electrical connection, leading to narrow bandwidth.
Innovation Solution
The optical modulator is designed with polymer patterns formed along the edges of the optical IC chip, allowing for shorter metal wire connections and improved impedance matching by forming polymer patterns along one edge, such as the termination edge, to reduce reflection and enhance bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a polymer is formed on the optical waveguide to achieve sufficient modulation without increasing drive voltage, then modulation efficiency is improved, but long metal wires are needed for electrical connection leading to high characteristic impedance and impedance mismatching
Solution Approach 1:
The patent positions the polymer pattern along the edge of the optical IC chip rather than in the center, utilizing the edge dimension to reduce the length of metal wires required for electrical connection. This spatial reconfiguration in the dimensional layout directly addresses the impedance matching issue by minimizing wire length.
Solution Approach 2:
The polymer is selectively formed only in specific regions where optical waveguides are present, rather than uniformly across the entire chip. This localized formation optimizes the balance between achieving sufficient modulation where needed and minimizing the overall area that requires electrical connection, thereby reducing metal wire length and improving impedance matching.
2Reliability
If the polymer is formed without overlapping wiring patterns, then optical performance is maintained, but long metal wires are required leading to narrow bandwidth
Solution Approach 1:
The patent utilizes the edge region of the optical IC chip for polymer formation, which is a different spatial dimension from the central region where wiring patterns are located. This allows the polymer to be formed without overlapping wiring patterns while minimizing metal wire length, thereby maintaining optical performance and improving bandwidth simultaneously.
3Volume of moving object
If the optical modulator is formed on a silicon substrate to reduce size, then device size is reduced, but power consumption increases
Solution Approach 1:
The patent uses a polymer material formed on the silicon substrate optical waveguide. The polymer provides a higher refractive index change in response to electric field compared to the silicon substrate alone, enabling sufficient modulation with lower drive voltage and reduced power consumption while maintaining the compact size achieved through silicon substrate integration.
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 configuration reduces the length of metal wires, facilitating impedance matching and increasing the bandwidth of the optical modulator, thereby enhancing the speed of optical signals.
Implementation Method 1
The refractive index of the optical waveguide changes greatly based on a change in the electric field applied to the polymer
Data Source
AI summary
An optical device includes an optical modulator formed on an optical IC chip. A shape of the IC chip is a rectangle or a parallelogram. The optical modulator includes an interferometer, wiring patterns, a first polymer pattern, and a second polymer pattern. The interferometer includes an optical waveguide that is formed in a direction from a first edge to a second edge of the optical IC chip. The wiring patterns are formed parallel to the optical waveguide. The first polymer pattern is formed along the first edge or the second edge. The second polymer pattern is connected to the first polymer pattern and formed on the optical waveguide without overlapping the wiring patterns.