GSSG Optical Modulator Crosstalk Suppression
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Solution Overview
Problem
Integrated optical modulators with a GSGSG type electrode structure face challenges in minimizing crosstalk and size due to the large number of electrodes, leading to increased optical loss and modulation quality deterioration as modulation speed increases, while GSSG type structures exacerbate crosstalk due to wider ground electrode clearance.
Innovation Solution
An optical modulator with a GSSG type differential electrode structure and a crosstalk suppressing unit in the ground electrode, where the upper surfaces of the ground electrodes are higher and lower surfaces are lower than the signal electrodes, and side surface portions are separated from the main body with partial electrical connection, to reduce crosstalk and enable low-voltage operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a GSGSG type electrode structure is used, then the number of electrodes is reduced, but the clearance between ground electrodes is wider causing electric field leakage and increased crosstalk
Solution Approach 1:
The ground electrode is segmented into multiple sections along the optical waveguide direction. By dividing the ground electrode into segments, the patent maintains the reduced electrode count advantage of GSSG structure while controlling electric field distribution to prevent crosstalk between adjacent modulation units.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the ground electrode. Specifically, the ground electrode has varying clearance distances at different positions, with smaller clearances near adjacent modulation units to suppress electric field leakage and crosstalk, while maintaining larger clearances elsewhere to reduce overall device complexity.
2Object-generated harmful factors
If the clearance between optical waveguides is widened to suppress crosstalk, then the crosstalk phenomenon is reduced, but the bending length increases and optical loss increases
Solution Approach 1:
The patent implements position-dependent clearance design where the distance between optical waveguides varies along the propagation direction. The clearance is minimized only in critical regions where crosstalk suppression is most needed, while maintaining shorter bending lengths in non-critical regions to reduce optical loss.
Solution Approach 2:
The ground electrode structure serves as an intermediary element that actively manages electric field distribution. By carefully designing the ground electrode clearance and position, it mediates between the need for crosstalk suppression and the need to minimize optical path length and bending losses.
3Speed
If the modulation speed is increased, then the transmission rate is improved, but the crosstalk phenomenon becomes more remarkable and modulation output quality deteriorates
Solution Approach 1:
The patent optimizes the ground electrode structure with position-varying clearance to create localized electric field confinement. This allows high-speed modulation signals to be transmitted while preventing crosstalk interference that would otherwise become more pronounced at higher speeds.
Solution Approach 2:
The ground electrode configuration is designed in advance to counteract the crosstalk effect before it can significantly impact high-speed signals. By pre-configuring the electrode clearance and position, the structure proactively suppresses electric field leakage that would otherwise exacerbate crosstalk at high modulation speeds.
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 crosstalk and allows for low-voltage operation by utilizing the electric field between signal electrodes and ground electrodes, enhancing modulation efficiency and reducing the size and optical loss of the modulator.
Implementation Method 1
a substrate having an electro-optic effect, and an optical waveguide and a control electrode that are formed on the substrate
Data Source
AI summary
To provide an optical modulator in which a plurality of Mach-Zehnder type optical waveguides are integrated, which can be driven at a low voltage, and in which the occurrence of a crosstalk phenomenon is suppressed. Provided is an optical modulator including a substrate 1 having an electro-optic effect, and an optical waveguide 10 and a control electrode that are formed on the substrate, in which the optical waveguide has a structure in which a plurality of Mach-Zehnder type optical waveguides are disposed in parallel, the control electrode has a GSSG type differential electrode structure in which two signal electrodes S are disposed between two ground electrodes G for one of the Mach-Zehnder type optical waveguides, and a crosstalk suppressing unit that suppresses signal crosstalk is provided in the ground electrode sandwiched between adjacent Mach-Zehnder type optical waveguides, so that optical modulator can be driven at a low voltage, and in which the occurrence of a crosstalk phenomenon is suppressed.