Mach-Zehnder Modulator Backplane Voltage Equalization
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Solution Overview
Problem
Series push-pull travelling wave Mach-Zehnder modulators face instability issues, particularly when high optical powers are coupled into the input waveguide, especially for modulators fabricated from direct bandgap semiconductors like indium gallium arsenide phosphide, due to non-uniformity in backplane voltage, affecting optical phase shift and performance.
Innovation Solution
Incorporating a conductive backplane with voltage control taps that provide equalizing DC control voltage underneath the travelling wave electrode, ensuring uniform voltage distribution and improved stability by minimizing parasitic DC currents and enhancing voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high optical powers are coupled into the input waveguide, then the optical signal strength is improved, but non-uniformity in backplane voltage occurs causing instability
Solution Approach 1:
The patent applies equipotentiality by introducing a conductive backplane with voltage control taps that distribute equalizing DC control voltage across the backplane structure. This creates equipotential regions that counteract the non-uniform voltage distribution caused by high optical powers, thereby maintaining modulator stability while allowing high optical signal strength.
2Stability of the object's composition
If a conductive backplane with voltage control taps is incorporated, then voltage distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The backplane is segmented into multiple regions with discrete voltage control taps at specific locations. This segmentation allows localized voltage control to achieve overall uniformity without requiring a completely redesigned complex backplane structure. The segmented approach with strategic tap placement provides an efficient balance between voltage uniformity and structural complexity.
3Object-generated harmful factors
If voltage control taps are added to equalize backplane voltage, then parasitic DC currents are reduced, but manufacturing complexity increases
Solution Approach 1:
The voltage control taps act as intermediary elements that mediate between the conductive backplane and external DC voltage sources. These taps provide controlled voltage injection points that suppress parasitic DC currents without requiring fundamental changes to the manufacturing process. The intermediary taps can be integrated using standard semiconductor fabrication techniques, maintaining ease of manufacture while eliminating harmful parasitic currents.
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 stabilizes the modulator performance by maintaining consistent voltage distribution along the backplane, reducing the impact of high optical powers and improving the optical phase shift per unit electrical signal change, thereby enhancing the modulator's stability and efficiency.
Implementation Method 1
a conductive backplane with voltage control taps that provide equalizing DC control voltage underneath the travelling wave electrode, ensuring uniform voltage distribution
Implementation Method 2
a beamsplitter divides the laser light from an input optical waveguide into two optical beams propagating in parallel waveguides defining optical paths, at least one of which having a phase modulator in which the refractive index is a function of the strength of the locally applied electric field
Data Source
AI summary
Mach-Zehnder optical modulators and IQ modulators based on a series push-pull travelling wave electrode are provided. The modulator includes a conductive backplane providing an electrical signal path. One or more voltage control taps are electrically connected to the conductive backplane within an area underneath the travelling wave electrode and provide an equalizing DC control voltage to the conductive backplane. In other variants, a plurality of conductive backplane segments are provided, and at least one voltage control tap is electrically connected to each conductive backplane segment within an area underneath the travelling wave electrode and provides a DC control voltage to the corresponding conductive backplane segment.