Optical Modulator Shield Layer for Crosstalk Reduction
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Solution Overview
Problem
Traveling-wave electrode modulators experience crosstalk and high electromagnetic radiation due to electromagnetic field coupling between channels, which affects signal quality and bit error rate.
Innovation Solution
An optical modulator design incorporating a shield layer with a metal layer and dielectric substrate to provide electromagnetic shielding, matching the effective refractive index of the optical waveguide, and using conductive vias for efficient shielding across multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple channels are integrated on the chip to increase modulation capacity, then the channel density increases, but crosstalk between adjacent channels increases
Solution Approach 1:
The patent divides the chip into separate modules, each containing a single channel's traveling-wave electrode modulator. This segmentation physically isolates adjacent channels, preventing electromagnetic field coupling and crosstalk while maintaining high channel density through modular integration.
Solution Approach 2:
The patent introduces a ground layer positioned between the signal electrodes of adjacent channels as an intermediary shielding structure. This ground layer acts as a mediator that blocks electromagnetic fields from one channel from coupling into adjacent channels, effectively reducing crosstalk while allowing close channel spacing.
2Productivity
If traveling-wave electrodes are used to achieve high-speed modulation, then electro-optic modulation performance improves, but electromagnetic radiation increases
Solution Approach 1:
The patent converts the harmful electromagnetic radiation from traveling-wave electrodes into a beneficial shielding effect. By introducing a ground layer and metal shield structure, the electromagnetic fields that would otherwise radiate harmfully are redirected to provide electromagnetic shielding, protecting adjacent channels while maintaining the high-speed modulation performance of the traveling-wave electrode structure.
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
Effectively prevents crosstalk and reduces electromagnetic radiation, enhancing the electro-optic modulation bandwidth and performance by ensuring electromagnetic and light wave velocity matching.
Implementation Method 1
the metal layer being disposed on the surface of the substrate facing away from the traveling-wave electrode. Each of the ground electrodes is electrically connected to the metal layer to provide electromagnetic shielding for the signal electrodes between the ground electrodes
Implementation Method 2
selecting a dielectric material that has a suitable dielectric constant to form the substrate of the shield layer covering the traveling-wave electrode may enable the effective dielectric constant of the material around the traveling-wave electrode to match the effective refractive index of the optical waveguide, thereby enabling the velocity of propagation of the electromagnetic wave to be the same as the velocity of propagation of the light wave
Implementation Method 3
A change in the electric field produced by the high-speed digital signal in the traveling-wave electrode 120 causes a change to the effective refractive index of the optical waveguide 130. Therefore, when the high-speed digital signal propagates in the traveling-wave electrode 120, the electric field of the high-speed digital signal causes a change to the refractive index of the optical waveguide 130, thereby causing a change to the phase of the light wave and causing the light wave to carry the digital signal information
Data Source
AI summary
An optical modulator includes: a bottom substrate layer, having a first surface; a traveling-wave electrode, being disposed on the first surface of the bottom substrate layer and including a plurality of ground electrodes and a plurality of signal electrodes between the ground electrode; an optical waveguide disposed inside the bottom substrate layer; and a shield layer, including a substrate and a metal layer, the substrate covering at least a portion of the traveling-wave electrode and the metal layer being disposed on the surface of the substrate facing away from the traveling-wave electrode. Each of the ground electrodes is electrically connected to the metal layer to provide electromagnetic shielding for the signal electrodes between the ground electrodes.