Optical Modulator Electrode Routing for Branch Ratio Stability
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Solution Overview
Problem
High-speed electrical signals in optical modulators cause transmission loss and deterioration of transmission characteristics when the signal electrode crosses the optical branching or combining parts, affecting the branch ratio and extinction ratio of light waves.
Innovation Solution
An optical modulator with a suppressing unit, such as a resin layer, is used between the optical waveguide and the modulation electrode to minimize the impact of the signal electrode crossing the optical branching or combining parts, ensuring the intensity ratio remains stable by positioning the signal electrode carefully and using a resin layer with specific properties to disperse electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the signal electrode is introduced from the long side portion of the substrate, then the electrical signal transmission path is established, but the signal electrode crosses the optical branching part causing changes in light intensity ratio and deterioration of transmission characteristics
Solution Approach 1:
The signal electrode is segmented into multiple sections: a first signal electrode introduced from the long side, a second signal electrode introduced from the short side, and these are connected through an overlapping region. This segmentation allows the electrode to avoid crossing the optical branching part while maintaining electrical continuity, thus preventing changes in light intensity ratio.
Solution Approach 2:
An overlapping region serves as an intermediary connection between the first and second signal electrodes. This intermediate structure allows the signal to be transmitted without the electrode directly crossing the optical branching part, thereby maintaining transmission characteristics while establishing the electrical connection.
2Ease of manufacture
If the signal electrode crosses the optical branching part, then the electrical connection is simplified, but the branch ratio and extinction ratio are affected causing transmission loss
Solution Approach 1:
The electrode path is divided into segments that introduce the signal from both long and short sides of the substrate. This segmented approach maintains manufacturing simplicity by using standard electrode introduction methods while avoiding the harmful crossing of the optical branching part, thus preventing transmission loss.
Solution Approach 2:
The electrode routing utilizes both the long side and short side dimensions of the substrate, transitioning from a single-dimension routing approach to a two-dimensional routing strategy. This allows the electrode to reach the modulation region without crossing the optical branching part, maintaining ease of manufacture while eliminating transmission loss.
3Speed
If high-speed electrical signals are transmitted through the signal electrode, then the modulation speed is improved, but transmission loss increases when the electrode crosses the optical branching part
Solution Approach 1:
The high-speed signal transmission path is segmented into multiple electrode sections connected through an overlapping region. This segmentation enables high-speed modulation by maintaining direct electrical pathways while avoiding the optical branching part crossing, thus achieving high speed without increased transmission loss.
4Reliability
If the signal electrode is positioned to avoid the optical branching part, then transmission characteristics are maintained, but the electrode routing becomes more complex
Solution Approach 1:
The electrode is segmented into first and second signal electrodes introduced from different sides of the substrate, connected through an overlapping region. This segmentation maintains transmission characteristics by avoiding the optical branching part while keeping the routing relatively simple by utilizing the substrate's boundary edges.
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 solution effectively suppresses changes in the intensity ratio and branch ratio, thereby minimizing transmission loss and maintaining optimal transmission characteristics even when the signal electrode crosses critical parts of the optical waveguide.
Implementation Method 1
a resin layer with specific properties to disperse electric fields
Implementation Method 2
an optical waveguide and a modulation electrode for modulating a light wave propagating through the optical waveguide are formed on a substrate having an electro-optic effect
Data Source
AI summary
An optical modulator includes a substrate on which an optical waveguide and a modulation electrode that modulates a light wave propagating through the optical waveguide are formed, and a case housing the substrate, the optical waveguide includes at least an optical branching part that branches one light wave into two light waves or an optical combining part that combines two light waves into one light wave, the modulation electrode has a signal electrode and a ground electrode, and a part of the signal electrode is disposed so as to cross the optical branching part or the optical combining part, and the optical modulator is provided with a suppressing unit that suppresses changes in an intensity ratio of the light waves branched at the optical branching part or an intensity ratio of the light waves combined at the optical combining part, by the signal electrode.