Curved Single Mode Fiber for Higher Order Mode Elimination
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Solution Overview
Problem
In optical transmission using single mode fibers (SMFs), higher order modes are generated due to chromatic dispersion, leading to signal waveform deterioration and the need for a higher order mode filter to improve transmission quality, especially at higher bit rates.
Innovation Solution
An optical device is designed with a single mode fiber having a curved portion that converts the light propagating direction between vertical and horizontal directions, effectively eliminating higher order modes and functioning as a mode filter with a bending loss difference of 15 dB or greater between the fundamental and higher order modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher order mode elimination filter is formed by a curved waveguide in a planar lightwave circuit, then higher order modes are eliminated and transmission quality is improved, but the device complexity increases and the number of components increases
Solution Approach 1:
The patent combines the higher order mode elimination filter and the direction converter into a single integrated curved waveguide structure. This merging eliminates the need for separate components, reducing device complexity while maintaining transmission quality through effective higher order mode elimination and optical path conversion.
Solution Approach 2:
The curved waveguide structure performs multiple functions simultaneously: it acts as both a higher order mode elimination filter and a direction converter. This multi-functionality reduces the overall number of components needed in the system, simplifying the device while improving transmission quality.
2Reliability
If multiple separate components are used for mode elimination and direction conversion, then transmission quality is improved, but optical coupling losses increase and the configuration becomes more complex
Solution Approach 1:
By merging the mode elimination filter and direction converter into one integrated curved waveguide, the patent eliminates multiple optical coupling interfaces between separate components. This reduces optical coupling losses while maintaining transmission quality through the unified structure.
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 enables efficient elimination of higher order modes, reducing intermode interference and maintaining signal waveform quality, while also simplifying the configuration by reducing the number of components and minimizing optical coupling losses.
Implementation Method 1
the single mode fiber has a curved portion that curves with a predetermined radius of curvature, and the curved portion converts a propagating direction of the light between the first direction and a second direction that is different from the first direction
Implementation Method 2
the curved portion converts a propagating direction of the light between the first direction and a second direction that is different from the first direction, and radiates a higher order mode
Data Source
AI summary
An optical device includes a photoelectric conversion element provided on a substrate, and a single mode fiber configured to guide light input to and output from the photoelectric conversion element toward a first direction perpendicular or obliquely upward with respect to the substrate or from the first direction. The single mode fiber has a curved portion that curves with a predetermined radius of curvature. The curved portion converts a propagating direction of the light between the first direction and a second direction that is different from the first direction, and radiates a higher order mode.