Asymmetric Trapezoidal Waveguide Core for Optical Multiplexer
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Solution Overview
Problem
Existing optical waveguide-type multiplexers face challenges due to the dispersion in the gap width between waveguides, leading to variations in multiplexing properties and reduced productivity during manufacturing. Additionally, the efficiency of mode coupling in optical directional couplers is poor, particularly between red and blue light, resulting in suboptimal multiplexing performance.
Innovation Solution
The optical multiplexer incorporates a design with asymmetric core cross-sections of optical waveguides in the mode coupling regions, specifically trapezoidal shapes, to reduce the dispersion in multiplexing properties and enhance mode coupling efficiency. This configuration optimizes the ratio of coupling lengths for different wavelengths, improving the multiplexing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap width between waveguides is reduced to improve mode coupling efficiency, then the coupling efficiency between different wavelengths improves, but the dispersion in gap width during manufacturing increases leading to variations in multiplexing properties
Solution Approach 1:
The patent applies asymmetry by designing the waveguide core cross-section as a trapezoid rather than a symmetric shape. This asymmetric geometry creates different coupling characteristics for different wavelengths, allowing the system to achieve high coupling efficiency for both red and blue light simultaneously. The asymmetric shape compensates for manufacturing variations in gap width by providing a geometric configuration that maintains optimal coupling conditions across wavelength variations.
Solution Approach 2:
The patent changes the geometric parameters of the waveguide core, specifically using a trapezoidal cross-section with controlled top and bottom widths. By adjusting these dimensional parameters, the invention optimizes the mode coupling efficiency for multiple wavelengths while making the system less sensitive to manufacturing tolerances in the gap width between waveguides.
2Reliability
If the gap width between waveguides is reduced to enhance mode coupling, then the multiplexing performance improves, but the fluctuation in B/R ratio increases reducing manufacturing yield
Solution Approach 1:
The asymmetric trapezoidal waveguide core design enables the system to achieve stable multiplexing performance with reduced fluctuation in the B/R ratio. The geometric asymmetry creates a coupling mechanism that is less sensitive to gap width variations, thereby maintaining consistent multiplexing performance across manufactured units and improving manufacturing yield.
3Ease of manufacture
If symmetric waveguide cross-sections are used, then the manufacturing process is simpler, but the mode coupling efficiency between different wavelengths is poor
Solution Approach 1:
The patent deliberately introduces asymmetry in the waveguide core cross-section (trapezoidal shape) to overcome the limitations of symmetric designs. While the asymmetric shape adds some complexity to the manufacturing process, it dramatically improves the mode coupling efficiency between different wavelengths by creating optimized evanescent field overlap conditions that symmetric geometries cannot achieve.
Solution Approach 2:
By changing the cross-sectional geometry from symmetric to asymmetric (trapezoidal) and carefully controlling the dimensional parameters (top width, bottom width, height), the invention achieves superior mode coupling efficiency while keeping the manufacturing process feasible through standard semiconductor fabrication techniques.
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 use of asymmetric trapezoidal core cross-sections in the optical waveguides reduces the fluctuation in the B/R ratio, leading to more stable multiplexing properties and increased manufacturing yield. This design enhances the efficiency of mode coupling, particularly between red and blue light, thereby improving the overall multiplexing performance and facilitating miniaturization of optical waveguide-type multiplexers.
Implementation Method 1
light transfers between the optical waveguides in the first and second mode coupling regions in the multiplexing unit
Data Source
AI summary
An optical multiplexer includes a first and a second optical waveguides, and a multiplexing unit. The first and second optical waveguides have a first and a second mode coupling regions being proximate to each other with a predetermined gap width, the optical waveguides in the coupling regions form the multiplexing unit. Light transfers between the optical waveguides in the first and second mode coupling regions, first light in the optical waveguide in the first mode coupling region and second light in the optical waveguide in the first or second mode coupling regions having the wavelength different from the first light are multiplexed to one of the waveguides in the mode coupling regions, and the core cross-section of the optical waveguide at least in the first and second mode coupling regions in the first and second optical waveguides is asymmetric in the height direction.