Optical Control Device With Rear Ground Electrode for Impedance Matching
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Solution Overview
Problem
Existing optical control devices face challenges in achieving velocity matching and impedance matching between microwaves and optical waves, particularly with thin sheet-like substrates, leading to high driving voltages and temperature issues.
Innovation Solution
An optical control device with a sheet-like substrate of 10 μm or less, featuring a coplanar control electrode and an additional ground electrode positioned via a low dielectric constant layer, which enhances impedance matching and reduces driving voltage by increasing electrostatic capacitance and optimizing refractive index and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coplanar control electrode is used on a thin sheet-like substrate, then impedance matching with signal paths is improved, but the driving voltage becomes excessively high
Solution Approach 1:
The patent introduces a third dimension by placing a ground electrode on the rear surface of the sheet-like substrate, opposite to the signal electrode on the front surface. This vertical arrangement creates a capacitive coupling that reduces the driving voltage while maintaining impedance matching, resolving the contradiction between electrical performance and energy consumption.
Solution Approach 2:
The sheet-like substrate itself acts as an intermediary dielectric material between the signal electrode and the rear ground electrode. This intermediary structure enables efficient electric field coupling and capacitive interaction, allowing impedance matching to be achieved with reduced driving voltage requirements.
2Speed
If the substrate thickness is reduced to 10 μm or less, then velocity matching between microwave and optical wave is improved, but impedance matching becomes difficult to achieve
Solution Approach 1:
By arranging the ground electrode on the rear surface of the thin substrate, the patent creates a vertical capacitive coupling that compensates for the reduced horizontal dimensions. This three-dimensional electrode arrangement enables impedance matching to be maintained even as the substrate thickness is reduced to 10 μm or less, preserving both velocity matching and impedance matching properties.
Solution Approach 2:
The patent changes the spatial distribution parameters of the electrode structure by introducing a ground electrode on the rear surface. This parameter change allows the system to maintain appropriate impedance characteristics despite the reduced substrate thickness, enabling both velocity matching and impedance matching to coexist.
3Productivity
If the ground electrode is placed close to the signal electrode to enhance optical confinement, then electro-optical efficiency is improved, but velocity matching and impedance matching become difficult to achieve
Solution Approach 1:
The patent resolves this contradiction by moving the ground electrode to the rear surface of the substrate, creating a vertical separation that maintains optical confinement efficiency through capacitive coupling while preserving velocity matching and impedance matching properties that would be compromised by horizontal placement.
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 operation with reduced driving voltage, impedance matching, and temperature control, allowing for efficient high-speed modulation while using a low-driving-voltage driving device.
Implementation Method 1
a sheet-like substrate (1) which has an electro-optical effect
Implementation Method 2
a control electrode (4, 5) for controlling light which passes through the optical waveguide (2)
Data Source
AI summary
A light control element is provided with a thin board having electro-optical effects; an optical waveguide formed on the thin board; and a control electrode for controlling light that passes through the optical waveguide. The light control element performs speed matching between a microwave signal applied to the control electrode and the light, impedance matching of the microwaves, reduction of a driving voltage and high speed operation. In the control electrode of the light control element, a signal electrode and a grounding electrode are arranged on an upper side of the thin board, and on a lower side of the thin board, a second electrode including the grounding electrode is arranged. The second electrode is arranged not to exist below the signal electrode, especially for achieving impedance matching.