Optical Modulator Relay Substrate Aperture Ground Electrode Crosstalk
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Solution Overview
Problem
In optical modulators, the increased number of signal electrodes leads to crosstalk issues due to close integration and high-frequency modulation, causing degradation of modulation characteristics, particularly in miniaturized and integrated configurations where spacing between electrodes is minimized, leading to radiation mode leakage and reduced effectiveness of common ground electrodes in suppressing crosstalk.
Innovation Solution
The optical device incorporates a relay substrate with a ground electrode featuring an aperture between signal electrodes, which traps electric field lines, and optionally includes branched ground electrodes and through-holes with low dielectric constant materials to reduce mutual capacitance and crosstalk, while maintaining miniaturization and integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If spacing between signal electrodes is narrowed to minimize transmission loss, then transmission loss is reduced, but crosstalk between signal electrodes increases
Solution Approach 1:
The ground electrode is segmented by introducing apertures that divide it into multiple sections. This segmentation allows the ground electrode to more effectively isolate adjacent signal electrodes, suppressing crosstalk while maintaining narrow spacing for low transmission loss.
Solution Approach 2:
The ground electrode structure is modified locally by adding apertures at specific positions between signal electrodes. This local modification enhances the crosstalk suppression capability in critical areas without changing the overall electrode layout or increasing spacing.
2Object-generated harmful factors
If ground electrode is individually disposed with respect to each signal electrode to suppress crosstalk, then crosstalk suppression is improved, but device complexity increases
Solution Approach 1:
Multiple ground electrodes are merged into a single continuous ground electrode structure with apertures. This unified structure provides crosstalk suppression comparable to individually disposed ground electrodes while simplifying the electrode configuration and reducing fabrication complexity.
3Object-generated harmful factors
If resistive thin film is formed along ground electrode to absorb unnecessary electric field, then crosstalk is suppressed, but manufacturing complexity and material cost increase
Solution Approach 1:
The unnecessary electric field is extracted and contained within the aperture regions of the ground electrode rather than being absorbed by additional resistive materials. This approach achieves crosstalk suppression through geometric design alone, eliminating the need for complex resistive thin film formation processes.
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 effectively suppresses crosstalk between signal electrodes, even at short distances, thereby enhancing the modulation characteristics of the optical modulator by trapping radiation modes and reducing the use of expensive materials like gold.
Implementation Method 1
a aperture that is provided in the ground electrode at the adjacent portion... traps electric field lines
Implementation Method 2
an electro-optical substrate having an electro-optic effect... a phase of light, which propagates through an optical waveguide on the electro-optical substrate, varies in accordance with electric field intensity of a modulation signal
Data Source
AI summary
[Task] Reduction in crosstalk between signal electrodes.[Means for Resolution] An optical modulator 1 includes a relay substrate 3 including a substrate portion 30, and signal electrodes 31 and 32, and a ground electrode 33 which are provided on the substrate portion 30, and an optical waveguide substrate 4 including an electrode-optical substrate 40, signal electrodes 431 and 432, and an optical waveguide 42 which are provided on the electro-optical substrate 40. Modulation signals are input from ends 31a and 32a on one side of the signal electrodes 31 and 32, the other end 31b of the signal electrode 31 is electrically connected to the signal electrode 431, the other end 32b of the signal electrode 32 is electrically connected to the signal electrode 432, an optical wave, which propagates through the optical waveguide 42, is modulated by the modulation signals which propagate through the signal electrodes 431 and 432, the ground electrode 33 is provided between the signal electrodes 31 and 32, and the relay substrate 3 includes a first adjacent portion 44 at which the signal electrodes 31 and 32 are adjacent to each other, and a through-hole 30g that is provided in the ground electrode 33 at the first adjacent portion 44.