Mach-Zehnder Optical Modulator Capacitance for Phase Matching
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Solution Overview
Problem
Existing optical waveguide devices experience phase shifts in differential modulation signals due to asymmetrical segment electrodes and varying clearance distances, leading to inconsistent signal propagation.
Innovation Solution
The optical waveguide device incorporates capacitance adjustment mechanisms, including dummy electrodes and adjusted clearances between modulation and ground electrodes, to synchronize phase velocities and suppress signal phase shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If asymmetrical segment electrodes are used to apply differential modulation signals, then the optical waveguide device can be miniaturized and operated at low power consumption, but phase shifts occur in the modulation signals due to different electrode shapes and clearances
Solution Approach 1:
The patent introduces capacitance adjustment mechanisms that modify the electrical parameters of the electrode structure. By changing the capacitance values through dummy electrodes and adjusted clearances, the phase velocities of differential modulation signals are equalized, resolving the phase shift issue while maintaining the low-power operation enabled by the thin substrate
Solution Approach 2:
Dummy electrodes are introduced as intermediary elements between the signal electrodes and ground electrodes. These dummy electrodes do not directly apply modulation signals to the optical waveguide but serve to adjust the capacitance and phase velocity of the differential signals, acting as a mediator to synchronize signal phases
2Adaptability or versatility
If different shaped segment electrodes (T-shape and H-shape) are used, then the modulation can be applied to different regions of the optical waveguide, but the different shapes cause different propagation velocities and phase shifts
Solution Approach 1:
The patent compensates for the different propagation velocities caused by asymmetrical electrode shapes by introducing capacitance adjustment mechanisms. The dummy electrodes and adjusted clearances modify the electrical parameters to equalize the phase velocities, allowing different electrode shapes to coexist while maintaining signal synchronization
Solution Approach 2:
The capacitance adjustment is applied locally at specific positions where phase shifts occur. By placing dummy electrodes and adjusting clearances at strategic locations between the asymmetrical segment electrodes, the patent selectively modifies the electrical characteristics in those regions to achieve overall phase velocity equalization
3Area of stationary object
If varying clearances between proximity electrodes are used, then the electrode layout can be optimized for compactness, but the varying clearances result in different capacitances and phase shifts
Solution Approach 1:
The patent intentionally introduces controlled variations in capacitance through dummy electrodes and clearance adjustments to compensate for the phase shifts caused by varying clearances. This allows the electrode layout to remain compact while achieving phase velocity uniformity through parameter optimization
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 effectively stabilizes differential modulation signals, ensuring consistent propagation and reducing phase shifts, thereby enhancing the performance of optical modulation devices and transmission apparatus.
Implementation Method 1
a capacitance adjustment mechanism for adjusting a phase velocity of the modulation signal propagating through the modulation electrode is provided between the modulation electrode and the ground electrode which are adjacent to each other
Implementation Method 2
the capacitance adjustment mechanism may be a dummy electrode that is formed on a part of the modulation electrode or the ground electrode and does not generate an electric field to be applied to the branched waveguide
Implementation Method 3
two modulation electrodes are provided to apply a differential modulation signal to each of two branched waveguides configuring the Mach-Zehnder type optical waveguide
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
An optical waveguide device in which two modulation electrodes (E1, E2) are provided to apply a differential modulation signal to each of two branched waveguides 10 configuring the Mach-Zehnder type optical waveguide, wherein each of the modulation electrodes includes a plurality of proximity electrodes (PE11 to PE22) disposed in a divided manner along the branched waveguide, a signal electrode (LE1, LE2) for propagating the modulation signal, and a bypass electrode (BE1, BE2) connecting the proximity electrodes and the signal electrode, a ground electrode (G1, G2) is disposed to sandwich the two modulation electrodes (E1, E2), and a capacitance adjustment mechanisms LET11 and LET12 for adjusting a phase velocity of the modulation signal propagating through the modulation electrode is provided between the modulation electrode E1 and the ground electrode G1 which are adjacent to each other.