Resonant Electrode Light Control Element for Low Voltage Modulation
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Solution Overview
Problem
Resonant type optical modulators face challenges in stable operation at low driving voltage and high modulation efficiency due to crosstalk between electrodes, which limits their effectiveness and increases costs, especially when velocities of light and control signals do not match, leading to high driving voltages and manufacturing complexities.
Innovation Solution
A light control element with two resonant type electrodes having the same resonant frequency, where the shape, formation position, and feeding points allow odd mode coupling, enabling control signals with the same phase or phase difference to be fed, reducing crosstalk and allowing stable operation at lower voltages without the need for high-cost differential drivers or external phase shifters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a long resonant type electrode is used to reduce driving voltage through velocity matching, then modulation efficiency per unit length is improved, but crosstalk between electrodes increases and stable operation becomes difficult
Solution Approach 1:
The patent introduces asymmetry by making the ground electrode wider than the signal electrode. This asymmetric configuration creates an odd mode coupling effect that suppresses even mode crosstalk between adjacent resonant electrodes, enabling stable operation with long electrodes while maintaining low driving voltage
Solution Approach 2:
The patent changes the geometric parameters of the electrodes, specifically setting the ground electrode width to be larger than the signal electrode width. This parameter change fundamentally alters the coupling characteristics between electrodes, transforming the crosstalk suppression mechanism while maintaining the benefits of long resonant electrodes
2Area of stationary object
If the gap between optical waveguides is reduced for miniaturization, then device size is decreased, but crosstalk between electrodes increases
Solution Approach 1:
The asymmetric electrode configuration (wider ground electrode than signal electrode) creates odd mode coupling that is insensitive to even mode disturbances. This allows the optical waveguides to be placed closer together for miniaturization while the asymmetric electrode structure continues to suppress crosstalk effectively
Solution Approach 2:
The patent converts the potentially harmful crosstalk effect into a beneficial odd mode coupling effect. By designing the electrodes with asymmetric dimensions, the coupling between adjacent structures becomes the desired odd mode interaction rather than harmful even mode crosstalk, enabling miniaturization without performance degradation
3Productivity
If resonant type electrodes are used to achieve high modulation efficiency per unit length, then electrode length can be reduced, but driving voltage becomes very high when velocities do not match
Solution Approach 1:
The patent changes the velocity matching parameter by adjusting the electrode dimensions and configuration to achieve velocity matching between the optical and electrical signals. This parameter change allows the use of long resonant electrodes that provide both high modulation efficiency per unit length and reduced driving voltage
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 enables stable optical modulation at low driving voltage, reduces manufacturing costs, and allows for miniaturization of the device by minimizing the gap between optical waveguides, while maintaining high modulation efficiency even with crosstalk, thus improving the overall performance and cost-effectiveness of the light control element.
Implementation Method 1
when an electric signal with a characteristic frequency is input from a feeding point thereto, a standing wave of the electric signal arises in the electrode
Implementation Method 2
A substrate material having an electro-optic effect such as lithium niobate is used for the resonant type optical modulator, and the intensity or a phase of light which propagates through an optical waveguide is modulated by varying a refractive index of the optical waveguide formed on the substrate using a control electrode
Implementation Method 3
a shape and a formation position of each resonant type electrode, and a feeding point to each of the resonant type electrodes by the feeding electrode are set to allow odd mode coupling with each other
Data Source
AI summary
Provided is a light control element wherein stable operation at low driving voltage is possible. A light control element comprises a substrate (1) having an electro-optic effect, a plurality of optical waveguides (2) formed on said substrate (1), and a control electrode (3) which is formed on said substrate and controls the phase of the light that propagates through the optical waveguides (2), wherein the control electrode is provided with at least two resonance type electrodes (31, 32) having the same resonant frequencies, and power supply electrodes (41, 42) which supply a control signal to each resonance type electrode (31, 32); and the shape and forming position of each resonance type electrode (31, 32), and the supply position to each resonance type electrode (31, 32) according to the power supply electrode (41, 42) are set so as to allow odd mode coupling with respect to each other; and a control signal having the same phase or a prescribed phase difference is supplied to each resonance type electrode (31, 32) by the power supply electrode (41, 42).