Variable Length Mach-Zehnder Modulators for Uniform Vpi
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Solution Overview
Problem
In photonic integrated circuits (PICs) with multiple Mach-Zehnder modulators, the variation in Vπ values across different optical paths poses a challenge, as the circuitry may not be able to supply the entire range of required voltages, affecting the performance of each optical path.
Innovation Solution
The solution involves varying the lengths of Mach-Zehnder modulators on the PIC substrate to ensure uniform Vπ values across all optical paths, which can be achieved by adjusting the length of the modulator arms to compensate for variations due to wavelength and material dependencies, thereby allowing a common power supply to drive all modulators effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple modulators are provided on a PIC with different Vπ values, then each optical path can be optimized for its specific requirements, but the driver circuitry cannot supply the entire range of Vπ values required
Solution Approach 1:
The patent applies local quality by making each modulator arm length specific to the requirements of its optical path. Different modulator arms have different lengths (L1, L2, L3, L4) tailored to compensate for wavelength and material variations in each specific path, while all modulators share a common driver circuitry design with uniform voltage supply capability.
Solution Approach 2:
The patent changes the physical parameter of modulator arm length to adjust and equalize Vπ values across different optical paths. By varying the length parameter of the modulator arms, the patent achieves uniform Vπ requirements that can be satisfied by a common driver circuitry voltage supply.
2Adaptability or versatility
If multiple modulators are provided on a PIC with different Vπ values, then each optical path can be optimized for its specific requirements, but multiple driver circuits are required increasing device complexity
Solution Approach 1:
The patent achieves universality by designing a common driver circuitry that can drive all modulators uniformly. By equalizing Vπ values through adjusted modulator arm lengths, a single driver circuit design serves multiple optical paths, eliminating the need for multiple specialized driver circuits and reducing overall device complexity.
Solution Approach 2:
The patent changes the modulator arm length parameter to create uniform Vπ characteristics across all modulators, enabling a universal driver circuitry design to be applied to all optical paths without requiring path-specific driver circuits.
3Reliability
If discrete components are used for modulators, then each component can be independently optimized, but integration onto a common chip becomes difficult
Solution Approach 1:
The patent merges multiple independently optimized modulator components onto a single photonic integrated circuit chip. By designing the modulators with adjusted arm lengths during the integration process, the patent maintains the benefits of independent optimization while achieving compact integration on a common substrate with lasers, modulators, and optical combiners.
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 approach optimizes the performance of each optical path by ensuring consistent Vπ values, allowing for efficient modulation and combination of optical signals, enhancing the overall performance of the PIC by maintaining uniform insertion loss, bias points, and modulation bandwidth across all paths.
Implementation Method 1
A modulating signal is applied to an electrode adjacent one or both of the arms in order to change the effective refractive indices in the interferometer arms and to introduce a relative phase shift between the two optical signals
Data Source
AI summary
A photonic integrated circuit (PIC) having multiple Mach-Zehnder (MZ) modulators with different lengths is provided. The modulator lengths are selected to provide optimal performance for each optical path provided on the PIC.