Optical Edge Coupler Taper Layout for Lower TE Coupling Loss
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Solution Overview
Problem
Conventional optical edge couplers (ECs) face increased coupling loss due to deviations in waveguide width caused by dicing or polishing tolerances, particularly affecting the local oscillation light in the TE mode.
Innovation Solution
The optical device incorporates a first edge coupler and a second edge coupler, each with a taper portion, where the second taper portion has a smaller taper angle and longer taper length compared to the first taper portion, reducing waveguide width deviations and coupling losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional edge couplers are used with standard taper angles, then the device structure is simple and manufacturing is easier, but coupling loss increases due to waveguide width deviations from dicing or polishing tolerances
Solution Approach 1:
The patent applies local quality by differentiating the taper angles for different edge couplers based on their specific functions. The first edge coupler uses a first taper angle optimized for signal light coupling, while the second edge coupler uses a second taper angle optimized for local oscillation light coupling. This localized optimization reduces coupling losses caused by waveguide width deviations without requiring complete redesign of the entire device structure.
Solution Approach 2:
The patent changes the taper angle parameter differently for the first and second edge couplers. By adjusting the taper angle parameter according to the specific coupling requirements of each edge coupler, the patent compensates for waveguide width deviations caused by manufacturing tolerances, thereby reducing coupling loss while maintaining reasonable structural complexity.
2Loss of energy
If the waveguide width is increased to reduce coupling loss, then coupling efficiency improves, but the device becomes more sensitive to dicing position deviations
Solution Approach 1:
The patent changes the taper angle parameter to compensate for waveguide width deviations. By optimizing the taper angle, the patent reduces the sensitivity to dicing position deviations while maintaining reduced coupling loss, thus resolving the contradiction between coupling efficiency and manufacturing precision tolerance.
3Loss of energy
If the same taper angle is used for both edge couplers, then the device structure is simpler and manufacturing is easier, but coupling loss increases for the local oscillation light port
Solution Approach 1:
The patent applies local quality by assigning different taper angles to different edge couplers based on their specific coupling requirements. The second edge coupler, which handles local oscillation light, uses a specifically optimized taper angle to reduce its coupling loss, while the first edge coupler uses a different taper angle suited for signal light coupling.
Solution Approach 2:
The patent changes the taper angle parameter differently for each edge coupler to optimize their respective coupling performances. This parameter differentiation reduces the coupling loss for local oscillation light without requiring complete structural redesign, balancing performance improvement with manufacturing complexity.
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 significantly reduces the coupling loss between the optical device and the optical fibers, especially for the TE light in the local oscillation port, thereby enhancing the optical device's tolerance to dicing position deviations.
Implementation Method 1
The first taper portion directs light from the end face and is contained in the first edge coupler. The second taper portion directs light from the end face and is contained in the second edge coupler.
Data Source
AI summary
An optical device includes a first edge coupler that is connected to a polarization multiplexer-demultiplexer and that makes contact with an end face and a second edge coupler that is connected to an optical hybrid circuit and that makes contact with the end face. The optical device includes a first taper portion that directs light from the end face and that is contained in the first edge coupler and a second taper portion that directs light from the end face and that is contained in the second edge coupler. The second taper portion has a structure in which a taper angle of the second taper portion with respect to the end face is smaller than a taper angle of the first taper portion with respect to the end face.