Optical Modulator Signal Terminal Layout for High Frequency Loss Reduction
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Solution Overview
Problem
Existing optical modulators using LiNbO3 substrates face challenges in improving high frequency characteristics and stability, particularly in reducing high frequency loss and propagation length, which affects their performance in digital coherent transmission systems.
Innovation Solution
The optical modulator design features signal input terminals divided and disposed on opposite sides of the optical element substrate, with protrusion portions for mounting, allowing for shorter electrical lengths and reduced propagation loss, and symmetrical placement to minimize strain and deformation, thereby enhancing high frequency characteristics and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal input terminals are arranged in a line at the bottom portion of the package case, then the skew between signal propagation paths is reduced, but the electrical length of the signal propagation path becomes long, causing high frequency loss
Solution Approach 1:
The signal input terminals are segmented into multiple groups and disposed at different locations on the package case rather than arranged in a single line. This segmentation allows each terminal group to be positioned closer to its corresponding electrode, shortening the electrical length and reducing high frequency loss while maintaining skew balance through symmetric arrangement.
Solution Approach 2:
The arrangement of signal input terminals transitions from a one-dimensional linear arrangement at the bottom to a two-dimensional distributed arrangement on multiple surfaces of the package case. This dimensional change enables shorter electrical paths by allowing terminals to be positioned closer to their target electrodes in three-dimensional space.
2Loss of energy
If the electrical length of signal propagation path is shortened, then high frequency loss is reduced, but the package case structure becomes more complex
Solution Approach 1:
The protrusion portions of the package case serve multiple functions: they provide mechanical support for mounting the package case, and simultaneously serve as locations for disposing signal input terminals. This multi-functionality reduces the need for additional structural elements, thereby limiting the increase in overall structural complexity while achieving shorter electrical paths.
3Length of stationary object
If signal input terminals are disposed at multiple locations on the package case, then the electrical length is shortened, but the mounting structure becomes more complex
Solution Approach 1:
The protrusion portions serve dual purposes as both mounting structures for securing the package case to external devices and as locations for disposing signal input terminals. This integration of mounting and terminal disposal functions into single structural elements avoids the need for separate mounting features, thereby limiting the increase in mounting structure complexity.
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 reduces propagation loss, improves high frequency characteristics, and stabilizes the optical modulator's performance by shortening electrical paths and minimizing strain, leading to better bandwidth and reduced driving power, while preventing deformation-induced changes in optical characteristics.
Implementation Method 1
an optical element substrate which includes an optical waveguide and a plurality of electrodes that control light waves propagating through the optical waveguide
Data Source
AI summary
In an optical modulator, high frequency characteristics are improved and the stability thereof is improved. An optical modulator includes: an optical element substrate that includes an optical waveguide and a plurality of electrodes that control light waves propagating through the optical waveguide; and a package case that houses the optical element substrate, in which a plurality of signal input terminals, respectively electrically connected to the plurality of electrodes, are provided on the bottom surface of the package case, and the plurality of signal input terminals respectively electrically connected to the plurality of electrodes provided on the optical element substrate are divided and disposed on the sides facing each other with the optical element substrate interposed therebetween.