MZ Optical Modulator Ground Electrode Resonance Suppression
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Solution Overview
Problem
High-speed optical modulators face issues with frequency response deterioration and signal crosstalk due to resonance phenomena when conductive structures like DC electrodes are present near signal electrodes, leading to increased transmission loss and reduced integration density.
Innovation Solution
Incorporating a ground electrode in parallel to the signal electrodes in an MZ type optical modulator, which reduces the electric field interaction with surrounding conductors and prevents resonance, thereby improving frequency response and allowing for higher integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a DC electrode is arranged around a signal electrode in an MZ type optical modulator, then the structure can be more compact and integration density can be improved, but resonance phenomenon occurs between electrodes leading to deterioration of frequency response characteristics and increased signal crosstalk
Solution Approach 1:
A ground electrode is introduced as an intermediary element between the signal electrode and the DC electrode. This ground electrode acts as a shield that intercepts and redirects the electric field lines, preventing direct interaction between the signal electrode and surrounding conductive structures. By placing the ground electrode adjacent to the signal electrode and connecting it to ground potential, the harmful electric field interaction is blocked, thereby suppressing resonance phenomena and maintaining frequency response characteristics while allowing compact integration.
2Speed
If the length of the electrode is increased to several millimeters to several tens of millimeters using a traveling wave electrode, then high-speed optical modulation can be achieved, but transmission loss and reflection increase
Solution Approach 1:
The electrode structure parameters are optimized by introducing a ground electrode that modifies the electromagnetic field distribution along the traveling wave electrode. This changes the effective impedance and field confinement characteristics, allowing longer electrode lengths to be used without proportionally increasing transmission loss. The ground electrode helps maintain field confinement and reduces parasitic effects that would otherwise limit the useful length of the traveling wave electrode.
3Device complexity
If conductive structures are placed near signal electrodes to improve integration, then device density increases, but resonance occurs leading to increased signal crosstalk and deterioration of waveform quality
Solution Approach 1:
The ground electrode serves as a protective intermediary that shields the signal electrode from nearby conductive structures. By positioning the ground electrode adjacent to the signal electrode and connecting it to ground potential, it creates an electromagnetic shield that redirects field lines and prevents coupling between the signal electrode and surrounding conductors. This eliminates the resonance mechanism that would otherwise cause signal crosstalk and waveform distortion, enabling high-density integration without compromising signal integrity.
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 presence of a ground electrode suppresses resonance and transmission loss, enhancing waveform quality and reducing signal crosstalk, while enabling the integration of various elements at a higher density within the optical modulator.
Implementation Method 1
an optical modulator where, even in a case where a DC electrode is arranged around a signal electrode, a deterioration in frequency response characteristic is suppressed by suppressing a resonance phenomenon between electrodes in the vicinity of a radio frequency electrode
Implementation Method 2
As the principle of changing the phase of light, the Pockels effect is mainly used in LiNbO3
Implementation Method 3
the Pockels effect and the quantum confined stark effect (QCSE) are mainly used in InP and GaAs
Implementation Method 4
the carrier plasma effect is mainly used in Si
Data Source
AI summary
The MZ type optical modulator of the invention includes: a Si optical modulator including an input optical waveguide, two arm waveguides branching and guiding light input from the input optical waveguide, an output optical waveguide combining the light guided through the two arm waveguides and outputting the combined light, two signal electrodes for applying radio frequency signals that are arranged in parallel to the two arm waveguides respectively, and a DC electrode for applying a bias voltage that is provided between the two signal electrodes; and at least one ground electrode arranged in parallel to the two signal electrodes.