Curved Mode Coupler for Optical Circuit Manufacturing Tolerance
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Solution Overview
Problem
Manufacturing errors in waveguide width design lead to fluctuations in optical circuit characteristics, making it difficult to achieve intended functionality with high yield, especially in linear configurations where only one mode can be optimized.
Innovation Solution
Incorporating a curved portion in the mode coupler to match mode conversion conditions, reducing the dependence on waveguide widths and increasing manufacturing tolerance by ensuring propagation constants match across different modes, thus minimizing the impact of manufacturing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear mode coupler is used to convert between single mode and multi mode waveguides, then mode conversion function is achieved, but manufacturing errors in waveguide width cause fluctuation in optical characteristics
Solution Approach 1:
The patent applies curvature to the mode coupler structure by introducing a curved portion that bends the waveguide path. This curved configuration changes the mode conversion characteristics compared to a linear coupler, making the system less sensitive to waveguide width variations and manufacturing errors while maintaining the mode conversion function between single mode and multi mode waveguides.
Solution Approach 2:
The patent modifies the geometric parameters of the mode coupler by introducing a curved portion with specific radius of curvature. This parameter change alters the propagation constants and mode conversion conditions, enabling the system to tolerate wider variations in waveguide width while maintaining stable optical characteristics and reliable mode conversion.
2Productivity
If waveguide width is precisely designed to satisfy mode conversion conditions, then mode conversion efficiency is improved, but manufacturing errors cause fluctuation in propagation constants
Solution Approach 1:
The curved portion in the mode coupler introduces geometric curvature that modifies the mode conversion mechanism. This curvature allows the system to maintain high mode conversion efficiency while being less sensitive to precise waveguide width dimensions, as the curved geometry provides a more robust matching condition for propagation constants that is less vulnerable to manufacturing tolerances.
Solution Approach 2:
The curved mode coupler design inherently provides a buffer against manufacturing errors by changing the mode conversion mechanism. The curved geometry creates a more forgiving matching condition between single mode and multi mode waveguides, cushioning the system against variations in waveguide width and ensuring stable propagation constants even when manufacturing precision varies.
3Device complexity
If only one mode is optimized in a linear waveguide configuration, then manufacturing complexity is reduced, but sensitivity to waveguide width characteristics cannot be maintained at lowest level
Solution Approach 1:
The curved mode coupler configuration allows the system to maintain sensitivity to waveguide width characteristics at the lowest level while avoiding complex multi-mode optimization. The curvature introduces a geometric effect that inherently balances the mode conversion conditions, enabling the system to be less sensitive to manufacturing variations without requiring complex waveguide designs or multiple optimized modes.
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 curved mode coupler design reduces the influence of manufacturing errors, allowing for increased manufacturing tolerance and maintaining sensitivity to waveguide width variations, resulting in improved optical circuit performance.
Implementation Method 1
a mode conversion circuit that converts a zero-th order mode and a primary mode by setting combinations of waveguide widths to W0 and W1 so that propagation constants of the zero-th order mode and the primary mode propagating the single mode waveguide and the multi-mode waveguide, respectively, match each other at a target wavelength
Implementation Method 2
propagation constants of the zero-th order mode and the primary mode propagating the single mode waveguide and the multi-mode waveguide, respectively, match each other at a target wavelength
Implementation Method 3
maintaining a combination of waveguide widths satisfying a mode conversion condition, thereby reducing the field change of light with respect to a waveguide width
Data Source
AI summary
There is a manufacturing error even if an RGB coupler is appropriately designed, and thus a problem that it is difficult to achieve the function as designed with good yield arises. To solve this problem, an optical circuit with a first waveguide in which light in a zero-th order mode is guided and a second waveguide having a larger width than the first waveguide, in which light in a primary mode is guided in which the first and second waveguides at least include a first curved portion in a curve shape curved toward the first waveguide while maintaining a combination of waveguide widths satisfying mode conversion conditions is provided.