Optical Modulator Bent Waveguide RF Signal Loss
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Solution Overview
Problem
In optical modules with optical modulators, the increased mounting area due to parallel connection of input and output optical fibers leads to propagation loss of RF signals, as the RF terminal is often positioned far from the reception interface, resulting in longer wiring and increased signal loss.
Innovation Solution
The optical module design includes an optical modulator chip with a bent waveguide, where the bias electrode is placed between the light input and bent waveguide portions, and the signal electrode between the bent waveguide and light output portions, with the signal input terminal positioned closer to the reception interface than the bias input terminal, reducing the distance between the RF terminal and the reception interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the input optical fiber and output optical fiber are connected in parallel to one side of the optical modulator, then the mounting area of the optical modulator is reduced, but the RF terminal is positioned far from the reception interface, resulting in longer wiring and increased propagation loss of RF signals
Solution Approach 1:
The patent changes the spatial arrangement from a planar layout to a three-dimensional configuration by having the optical waveguide pass through the substrate. The input and output optical fibers are connected to opposite surfaces of the substrate, allowing the optical modulator to be mounted in a compact area while the electrical connections are routed through internal substrate pathways, thus reducing both mounting area and RF signal propagation loss.
Solution Approach 2:
The patent embeds the optical waveguide within the substrate structure, nesting the optical path through the substrate thickness. The input optical fiber connects to the first surface, the waveguide propagates through the substrate, and the output optical fiber connects to the opposite surface, creating a nested configuration that reduces mounting area while maintaining short electrical connection paths.
2Area of stationary object
If the RF terminal is positioned far from the reception interface to accommodate the bent waveguide configuration, then the mounting area is reduced, but the wiring length increases causing increased propagation loss
Solution Approach 1:
The patent utilizes the substrate thickness dimension to route the optical waveguide, allowing the RF terminal and reception interface to be positioned close to each other on the same surface while the optical path travels through the substrate. This dimensional transition separates the optical and electrical connection paths, reducing wiring length without compromising area reduction.
3Area of stationary object
If the bent portion of the optical waveguide is used to fold back light between input and output fibers, then the mounting area is reduced, but the RF electrode must be positioned away from the reception interface, increasing wiring complexity
Solution Approach 1:
The patent nests the optical waveguide within the substrate, with the bent portion configured to fold back light within the substrate volume. The RF electrode and reception interface are both positioned on the same surface of the substrate, simplifying the wiring arrangement while the nested waveguide configuration reduces the overall mounting area.
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 shortens the wiring between the RF terminal and the reception interface, thereby reducing the propagation loss of RF signals while minimizing the optical modulator's mounting area.
Implementation Method 1
a bent portion is provided in an optical waveguide on an optical modulator chip, and the bent portion of the optical waveguide folds back light between the end portion of the input optical fiber and the end portion of the output optical fiber
Implementation Method 2
an optical modulator for modulating light... a bias electrode to which a bias voltage is applied... and a signal electrode to which the electric signal is input
Data Source
AI summary
An optical modulator includes: an optical modulator chip having an optical waveguide having a bent waveguide portion that is bent between a light input end portion and a light output end portion, a bias electrode provided between the light input end portion and the bent waveguide portion along the optical waveguide, and a signal electrode provided between the bent waveguide portion and the light output end portion along the optical waveguide; a bias input terminal configured to input a bias voltage, the bias input terminal being electrically connected to the bias electrode, and a signal input terminal configured to input an electric signal, the signal input terminal being provided closer to a receiver configured to receive an electric signal than the bias input terminal and being electrically connected to the signal electrode.