Optical Modulator Size Reduction via 3D Wiring Layout
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Solution Overview
Problem
Conventional optical modulators face challenges in reducing size due to the large area occupied by electric wiring, which is not adequately considered in previous layout optimizations focused solely on optical waveguides, limiting the overall size reduction of the modulator.
Innovation Solution
The optical modulator design includes a substrate with an optical waveguide and electric wiring layout where the optical waveguide is arranged in a U-shape and the electric wiring is positioned on different end surfaces, allowing for reduced size and noise reduction by minimizing the length and interference of the electric wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the optical waveguide is arranged in a U-shape or S-shape to reduce its size, then the optical waveguide area is reduced, but the electric wiring area remains large and is not adequately optimized
Solution Approach 1:
The patent applies dimensionality change by routing electric wiring through different spatial dimensions - specifically, placing input electric wiring on a first surface of the substrate and output electric wiring on a second surface of the substrate. This vertical separation in the third dimension (depth/thickness) allows both input and output wiring to be positioned close to the modulation unit without increasing the planar footprint, thereby reducing the overall device area while maintaining wiring functionality.
2Area of moving object
If the electric wiring length is reduced to minimize area, then the device size is reduced, but maintaining characteristic impedance of 50Ω becomes difficult
Solution Approach 1:
The patent applies local quality by providing ground electrodes adjacent to the electric wiring at specific locations where impedance control is critical. The ground electrodes are positioned locally near the input and output wiring regions to maintain characteristic impedance of 50Ω at these key points, while allowing the overall wiring length to be minimized for area reduction. This localized impedance control ensures signal integrity without requiring the entire wiring path to be optimally designed.
3Object-affected harmful factors
If the ground line thickness is increased to reduce crosstalk, then the wiring area increases, but this limits further size reduction of the optical modulator
Solution Approach 1:
The patent applies dimensionality change by separating input and output electric wiring into different surfaces (first surface and second surface) of the substrate. This vertical separation in the third dimension significantly reduces crosstalk between input and output signals without requiring thicker ground lines. The ground electrodes are positioned on the same surface as their associated wiring, and the spatial separation between input and output wiring planes eliminates the need for excessive ground line thickness, thereby maintaining small device area while suppressing crosstalk.
4Area of moving object
If semiconductor optical modulator is used instead of LN optical modulator to reduce size, then the modulator size is reduced, but the electric wiring area becomes a relatively larger portion of the total chip area
Solution Approach 1:
The patent applies dimensionality change by routing electric wiring through the substrate thickness - placing input electric wiring on a first surface and output electric wiring on a second surface. This vertical arrangement allows both input and output wiring to be positioned in close proximity to the compact semiconductor optical modulator without increasing the planar footprint. The wiring utilizes the third dimension (depth) of the substrate, thereby minimizing the proportion of chip area occupied by electric wiring while maintaining all necessary electrical connections.
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 effectively reduces the size of the optical modulator while maintaining the characteristic impedance of the electric wiring, enabling more compact packaging suitable for smaller standards like CFP2 and CFP4, and reducing noise contamination.
Implementation Method 1
an optical waveguide provided on the substrate and configured to guide the light
Implementation Method 2
a modulation unit formed of part of the optical waveguide and configured to modulate the light
Data Source
AI summary
The present invention provides an optical modulator, which can be reduced in size with size reduction of an optical waveguide and electric wiring as compared to a conventional optical modulator. An optical modulator according to an embodiment includes a substrate; an optical waveguide provided on the substrate and configured to guide light; a modulation unit formed of part of the optical waveguide and configured to modulate the light; and electric wires provided on the substrate and configured to supply a high-frequency electric signal to the modulation unit. One end portion and another end portion of the optical waveguide are provided on a first end surface, one end portion of the electric wiring is provided along the first end surface, another end portion of the electric wiring is provided along a second end surface being different from the first end surface.