Coplanar Waveguide Wire Electrode for Velocity Matching
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Solution Overview
Problem
Designing a coplanar waveguide wire electrode structure for high-speed electro-optic modulators that ensures the transmission speed of electrical signals matches or closely resembles the group velocity of optical signals, while minimizing transmission loss.
Innovation Solution
The proposed coplanar waveguide wire electrode structure includes a metal electrode with a ground electrode, a signal electrode, and connecting arms, with signal and ground wire extension electrodes. This design ensures impedance matching and reduces the distance between electrodes, thereby increasing electric field intensity and minimizing signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coplanar waveguide wire electrode structure is designed to prevent microwave reflection by matching impedance, then the reliability of electrical signal transmission is improved, but the transmission speed may deviate from the group velocity of optical signals
Solution Approach 1:
The patent adjusts the geometric parameters of the electrode structure, specifically the width of the signal electrode and the distance between electrodes, to control the characteristic impedance and propagation velocity of the coplanar waveguide. By changing these parameters, the electrical signal transmission characteristics are optimized to match both impedance requirements and velocity synchronization requirements.
2Power
If the distance between electrodes is reduced to increase electric field intensity, then the modulation efficiency is improved, but the transmission loss of electrical signals increases
Solution Approach 1:
The patent employs connecting arms with varying widths and different electrode geometries at different positions along the coplanar waveguide. The connecting arms are designed with wider sections near the electrodes to concentrate electric field intensity for efficient modulation, while tapering to narrower sections away from electrodes to reduce capacitive coupling and transmission loss.
3Speed
If the connecting arms are designed to guide electrical signals, then the transmission speed control is improved, but the device complexity increases
Solution Approach 1:
The coplanar waveguide electrode structure is divided into multiple functional segments: input connecting arms, main signal electrodes with connecting arms, and output connecting arms. Each segment is optimized for its specific function - input arms for impedance matching, main electrodes for modulation, and output arms for signal extraction - allowing independent optimization of each segment to control transmission speed without requiring complex overall redesign.
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
The structure achieves reduced transmission loss of electrical signals by ensuring impedance consistency and matching the transmission speed of electrical signals with the group velocity of optical signals, while maintaining high modulation rates.
Implementation Method 1
The electro-optic modulator is a modulator made by an electro-optic effect of some electro-optic crystals, such as a lithium niobate (LiNbO3) crystal, a gallium arsenide (GaAs) crystal and a lithium tantalate (LiTaO3) crystal. The electro-optic effect means that, when a voltage is applied to the electro-optic crystal, the refractive index of the electro-optic crystal will be changed, resulting in a change in the characteristics of the light wave passing through the crystal, so as to realize the modulation of the phase, amplitude, intensity and polarization state of the optical signal.
Data Source
AI summary
A coplanar waveguide wire electrode structure and a modulator includes a metal electrode and an optical waveguide. The metal electrode includes ground electrodes and a signal electrode. Connecting arms are arranged on both sides of the signal electrode. The inner sides of the ground electrodes are provided with other connecting arms. The tail ends of the connecting arms of the signal electrode are provided with signal wire extension electrodes, and the tail ends of the connecting arms of the ground electrodes are provided with ground wire extension electrodes. A distance is provided between the signal wire extension electrodes and the ground wire extension electrodes. The optical waveguide passes through the spaces between the signal wire extension electrodes and the ground wire extension electrodes. By extending the metal electrode, the distance between the electrodes is actually shortened.