Coherent Optical Transmitter Electrode Configuration for Cross-Talk Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current IQ modulators face challenges in achieving high modulation bandwidth while maintaining low cross-talk and compact size, with existing technologies like lithium niobate requiring larger sizes and compound III-V semiconductor-based modulators struggling with cross-talk reduction.
Innovation Solution
The use of a travelling-wave electrode structure with a ground-signal-signal-ground (GSSG) configuration and bond wires to reduce cross-talk, allowing for low Vπ, high bandwidth, and compact size, while optimizing electro-optic frequency response for high-bitrate applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium niobate modulators are used to achieve low drive voltages, then the modulator size increases, but compact device configurations are required
Solution Approach 1:
The patent changes the material parameter from lithium niobate to compound III-V semiconductor (InP), which fundamentally alters the electro-optic coefficients and enables compact device configurations while maintaining acceptable drive voltages for high-bitrate applications
Solution Approach 2:
The patent employs composite material structures combining InP with other materials optimized for specific functions (electrode materials, waveguide materials) to achieve both compact size and low drive voltage requirements simultaneously
2Area of stationary object
If compound III-V semiconductor-based modulators are used for compact device configurations, then cross-talk increases, but low cross-talk operation is required
Solution Approach 1:
The patent extracts and eliminates the source of cross-talk by carefully designing the electrode configuration and spacing to prevent electromagnetic coupling between adjacent I and Q modulator sections, thereby removing the harmful interference while maintaining compact dimensions
Solution Approach 2:
The patent introduces intermediary elements such as ground electrodes and shielding structures between the I and Q modulator sections to prevent direct electromagnetic coupling, acting as mediators that block cross-talk while allowing the compact device configuration to be maintained
3Speed
If high modulation bandwidth is achieved, then signal integrity deteriorates due to cross-talk, but both high bandwidth and low cross-talk are required
Solution Approach 1:
The patent employs travelling-wave electrode structures that dynamically match the electrical signal velocity with the optical signal propagation, enabling high modulation bandwidth while maintaining signal integrity through continuous electro-optic interaction along the waveguide length
Solution Approach 2:
The patent transitions from conventional planar electrode configurations to three-dimensional electrode structures with optimized spacing and positioning, creating additional spatial dimensions for electromagnetic field control that reduce cross-talk while supporting high-bandwidth operation
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 significantly reduces cross-talk, achieving improved signal integrity and increased optical transport distances with reduced power consumption and smaller form factor, suitable for high-bitrate applications like 100 GBd signaling.
Implementation Method 1
an electro-optic frequency response optimized for high-bitrate applications
Data Source
AI summary
An electro-optical modulator includes a substrate comprising a first Mach-Zehnder modulator comprising a first waveguide and a second waveguide and a second Mach-Zehnder modulator comprising a first waveguide and a second waveguide. A first positive signal electrode is positioned on the substrate over the first waveguide of the first Mach-Zehnder modulator and a first negative signal electrode is positioned on the substrate over the second waveguide of the first Mach-Zehnder modulator. The first positive signal electrode and the first negative signal electrode are connected to a first differential signal input. A second positive signal electrode is positioned on the substrate over the first waveguide of the second Mach-Zehnder modulator and a second negative signal electrode positioned on the substrate over the second waveguide of the second Mach-Zehnder modulator. The second positive signal electrode and the second negative signal electrode are connected to a second differential signal input. A first ground electrode is positioned on the substrate between the first and second Mach-Zehnder modulators connected to ground potential. A second ground electrode is connected to ground potential and positioned on the substrate adjacent to the first Mach-Zehnder modulator such that the first positive signal electrode and the first negative signal electrode are between the second ground electrode and the first ground electrode. A third ground electrode is connected to ground potential and positioned on the substrate adjacent to the second Mach-Zehnder modulator such that the second positive signal electrode and the second negative signal electrode are between the third ground electrode and the first ground electrode. A plurality of first electrical connectors connect the first ground electrode to the second ground electrode and a plurality of second electrical connectors connect the first ground electrode to the third ground electrode. A spacing between at least two of the plurality of first electrical connectors is chosen to achieve a desired cross talk between an optical signal generated by the first Mach-Zehnder modulator and an optical signal generated by the second Mach-Zehnder modulator.