Optical Control Device Modulation Timing Matching
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Solution Overview
Problem
Optical control devices using anisotropic dielectric substrates face challenges in achieving accurate modulation timing and intensity matching due to varying propagation speeds and impedance mismatch among signal electrodes, leading to deteriorated modulation characteristics and different modulation start times for signals of different frequencies.
Innovation Solution
The optical control device employs an anisotropic dielectric substrate with optical waveguides and modulation electrodes, where signal electrodes are oriented in directions with different dielectric constants, ensuring matched impedance and effective electrode lengths, thereby maintaining consistent high-frequency characteristics across all electrodes, even when frequencies change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If signal electrodes are disposed in directions with different dielectric constants on an anisotropic dielectric substrate, then the propagation speed and impedance of electrical signals vary among signal electrodes, but this enables optical control devices to achieve high-speed modulation. However, this causes different propagation times and impedance mismatches among signal electrodes, deteriorating modulation characteristics
Solution Approach 1:
The patent applies local quality by making each signal electrode have a different effective length tailored to its specific propagation characteristics. Signal electrodes in directions with higher propagation speed are given longer effective lengths, while those in directions with lower propagation speed have shorter effective lengths. This local adjustment compensates for the anisotropic propagation differences, ensuring that all signal electrodes achieve synchronized modulation timing despite operating in directions with different dielectric constants.
Solution Approach 2:
The patent changes the parameter of effective electrode length to compensate for propagation time differences. By adjusting the effective length parameter of each signal electrode based on its propagation characteristics (propagation speed and impedance), the system achieves consistent modulation timing across all electrodes. The effective length is calculated considering both the physical length and the propagation characteristics in each direction, allowing parameter optimization for each electrode location.
2Manufacturing precision
If the effective electrode lengths of input-side signal electrode portions are adjusted to be the same, then the physical lengths can be equalized, but the electrical reflection and propagation loss resulting from impedance mismatch remain different in each modulation electrode due to anisotropic dielectric properties
Solution Approach 1:
The patent applies local quality by adjusting the effective length of each signal electrode according to its specific propagation characteristics rather than using uniform effective lengths. Each electrode's effective length is optimized locally to compensate for the anisotropic propagation differences in its direction, thereby reducing impedance mismatch and propagation loss while maintaining manufacturing feasibility.
Solution Approach 2:
The patent introduces asymmetry in the effective lengths of signal electrodes to compensate for the anisotropic propagation characteristics. Instead of symmetric uniform lengths, the system uses asymmetric effective lengths tailored to each electrode's propagation direction and speed, thereby balancing the overall system performance and reducing energy loss from impedance mismatch.
3Device complexity
If electrical signals of different frequencies are input to modulation electrodes having the same shape, then the structure is simplified, but the modulation start time becomes different in each modulation electrode due to frequency-dependent refractive index changes
Solution Approach 1:
The patent changes the parameter of effective electrode length to compensate for frequency-dependent propagation time differences. By optimizing the effective length parameter for each electrode based on its propagation characteristics, the system achieves frequency-insensitive timing synchronization. This parameter adjustment ensures that modulation start times remain consistent across different frequencies without requiring complex frequency-specific electrode structures.
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 configuration allows for precise matching of modulation timing and intensity, reducing propagation loss and impedance mismatch, resulting in improved modulation quality and jitter characteristics, suitable for high-speed modulation methods like DQPSK and SSB.
Implementation Method 1
when material (anisotropic dielectric substrate) having anisotropy in dielectric constant is used, since the high-frequency refractive index also has anisotropy, the propagation speed, impedance and propagation loss of the electrical signals may change depending on propagation direction
Implementation Method 2
optical control devices have become commercially available in which an optical waveguide, a signal electrode, and a ground electrode are formed on a substrate having an electro-optical effect, and a high-frequency signal is applied to the signal electrode to modulate an optical wave propagating through the optical waveguide
Data Source
AI summary
The present invention relates to an optical control device capable of achieving an accurate match of modulation timing and modulation intensity between optical waves propagating through optical waveguides disposed between a plurality of signal electrodes in an optical control device using an anisotropic dielectric substrate.