Optical Integrated Circuit Element with Asymmetrical Waveguides
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Solution Overview
Problem
Existing optical integrated circuit elements combining mode converters and directional couplers are not robust against manufacturing errors, especially when produced using a 0.18 µm process, leading to difficulty in controlling their characteristics, particularly in asymmetrical structures.
Innovation Solution
An optical integrated circuit element with a polarization splitter rotator and delayers/variable optical attenuators is designed to compensate for manufacturing errors, using asymmetrical waveguides and adjustable refractive indices to stabilize polarization separation and rotation, even in 0.18 µm processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a combination of mode converter and directional coupler is used to achieve polarization separation and rotation, then the polarization splitting function is achieved, but the element becomes sensitive to manufacturing errors and difficult to control
Solution Approach 1:
The patent applies asymmetry by designing the waveguide with a specific cross-sectional shape that lacks linear symmetry. This asymmetrical waveguide structure inherently provides polarization splitting functionality without requiring the combination of mode converter and directional coupler, thereby reducing sensitivity to manufacturing errors and improving robustness.
Solution Approach 2:
The patent extracts and eliminates the mode converter component from the traditional combination of mode converter and directional coupler. By using only an asymmetrical waveguide, the patent simplifies the structure while maintaining polarization splitting functionality, reducing the impact of manufacturing errors on overall system performance.
2Adaptability or versatility
If asymmetrical structures are used in optical integrated circuit elements, then polarization separation is achieved, but controlling the characteristics becomes difficult especially in 0.18 µm processes
Solution Approach 1:
The patent employs an asymmetrical waveguide cross-sectional shape to achieve polarization separation. The specific asymmetrical design allows the waveguide to naturally split different polarizations while the overall structure remains compatible with standard fabrication processes, including 0.18 µm processes.
Solution Approach 2:
The patent applies local quality by creating asymmetry only in the cross-sectional shape of the waveguide while maintaining regularity in the longitudinal structure. This localized asymmetry provides the necessary polarization splitting function without making the entire structure difficult to manufacture or control.
3Ease of manufacture
If standard waveguide structures with linear symmetry are used, then manufacturing is easier, but polarization separation and rotation cannot be achieved
Solution Approach 1:
The patent introduces asymmetry in the waveguide's cross-sectional shape, which breaks the linear symmetry of standard waveguides. This asymmetrical design enables polarization separation and rotation functions while the waveguide can still be fabricated using conventional processes by precisely controlling the cross-sectional dimensions.
Solution Approach 2:
The patent achieves polarization functionality by modifying the cross-sectional dimension of the waveguide rather than complicating the longitudinal structure. By introducing asymmetry in the transverse plane (cross-section), the waveguide gains polarization splitting capability while maintaining compatibility with standard fabrication approaches.
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 enhances the reliability and uniformity of optical signal detection by reducing jitter and optical loss, improving the robustness of optical communication systems against varying polarizations and wavelengths.
Implementation Method 1
a first waveguide and a second waveguide... The first waveguide includes a first port configured to allow input or output of electromagnetic waves that include a first polarization and a second polarization, and a second port configured to allow output of the first polarization that has been separated
Implementation Method 2
The second waveguide includes a third port configured to allow output of the second polarization that has been separated and rotated
Data Source
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AI summary
An optical integrated circuit element includes a first waveguide and a second waveguide. At least part of the first waveguide and at least part of the second waveguide are positioned alongside each other along a first direction. The first waveguide includes a first port configured to allow input or output of electromagnetic waves that include a first polarization and a second polarization, and a second port configured to allow output of the first polarization that has been separated or input of the first polarization. The second waveguide may include a third port configured to allow output of the second polarization that has been separated or the second polarization that has been separated and rotated, or input of the second polarization. A cross-sectional shape, a normal to which is the first direction, of at least one of the first waveguide or the second waveguide does not have linear symmetry.