Nested Modulator Electrode Simplification for Low Drive Voltage
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Solution Overview
Problem
Conventional nested modulators face challenges in simplifying the circuit arrangement of modulating electrodes and achieving lower drive voltage, particularly due to the complexity of wiring and high drive voltage requirements when using X cut plates, and the difficulty in adjusting signal electrode lengths for Z cut plates.
Innovation Solution
A nested modulator design featuring a substrate with polarization reversal regions and branching signal electrodes that work on two sub-branching waveguides, allowing for a single signal electrode to be introduced into each sub-Mach-Zehnder waveguide, simplifying wiring and enabling efficient modulation with equal drive voltage, using a Z cut plate made of lithium niobate or lithium tantalate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single signal electrode is formed for each sub-MZ waveguide (X cut plate configuration), then the structure becomes relatively simple, but the waveguides and signal electrodes are at a distance from each other causing high drive voltage
Solution Approach 1:
The patent merges multiple signal electrodes into a single shared signal electrode that serves both sub-MZ waveguides. This single electrode is positioned to electrically interact with both waveguides simultaneously, combining the electrode function to reduce overall device complexity while maintaining effective modulation of both waveguides.
Solution Approach 2:
The patent introduces a ground electrode as an intermediary element positioned between the signal electrode and the sub-MZ waveguides. This ground electrode acts as a mediator to enhance the electrical field interaction, allowing the single signal electrode to effectively modulate both waveguides at lower drive voltages by providing a reference potential and field concentration path.
2Power
If Z cut plate is used to locate signal electrodes in close proximity to sub-branching waveguides, then drive voltage can be lowered, but wiring of signal electrodes becomes complicated and adjustment of electrode length becomes very difficult
Solution Approach 1:
The patent combines multiple signal electrodes into a single shared signal electrode structure that interfaces with both sub-MZ waveguides. This merging approach simplifies the wiring architecture by eliminating the need for separate electrode connections to each waveguide, thereby reducing wiring complexity while maintaining close proximity for effective modulation at low drive voltage.
Solution Approach 2:
The single signal electrode is designed to perform multiple functions by simultaneously modulating both sub-MZ waveguides. This multi-functional electrode structure eliminates the need for separate dedicated electrodes for each waveguide, simplifying the overall wiring arrangement while achieving the desired low drive voltage operation through close proximity positioning.
3Power
If Z cut plate is used with multiple signal electrodes for each sub-MZ waveguide, then drive voltage is lowered, but it becomes very difficult to adjust the length of signal electrode between signal entrance and modulation portion
Solution Approach 1:
The patent merges the signal electrode functions into a single electrode structure that serves both sub-MZ waveguides. This unified electrode design eliminates the need for separate length adjustments for multiple electrodes, making the adjustment process simpler and more straightforward while maintaining optimal modulation performance at low drive voltage.
Solution Approach 2:
The patent segments the single signal electrode into distinct functional regions: a signal entrance portion for electrical connection and a modulation portion that interacts with the optical waveguides. This segmentation allows independent optimization and adjustment of each region, facilitating easier length adjustment and positioning to achieve optimal modulation performance.
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 design simplifies the electrode circuit arrangement, reduces drive voltage, and enables efficient optical modulation with equal modulation intensity in opposite phases across sub-branching waveguides, achieving high modulation efficiency.
Implementation Method 1
a substrate made of a material having electro-optic effects
Data Source
AI summary
A nested modulator is provided where the circuit arrangement of modifying electrodes including signal electrodes is simplified, and at the same time, the drive voltage can be lowered.A nested modulator, including: a substrate 20 made of a material having electro-optic effects; an optical waveguide formed on the substrate; and a modulating electrode for modulating light waves which are guided through the optical waveguide, wherein the optical waveguide has a main Mach-Zehnder waveguide 1 and sub-Mach-Zehnder waveguides 2 and 3 provided on two branching waveguides of the main Mach-Zehnder waveguide, and the modulating electrode is provided in a sub-branching waveguide of the sub-Mach-Zehnder waveguides, is characterized in that a polarization reversal region 46 or 47 is formed in a portion of a sub-branching waveguide of each of the sub-Mach-Zehnder waveguides, the modulating electrode is formed of signal electrodes including introduced signal electrodes 40 or 43, branching single electrodes 41 or 44 and lead signal electrodes 42 or 45 as well as ground electrodes for each of sub-Mach-Zehnder waveguides, and the branching signal electrodes which branch from the introduced signal electrode are placed so as to work on two sub-branching waveguides for each of the sub-Mach-Zehnder waveguides.