Wavelength Selective All-Fiber Coupler Using Graded Index Cores
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Solution Overview
Problem
Existing all-fiber couplers are not wavelength selective and require heavy tapering or specialty fibers, making them unreliable for high-power applications and labor-intensive to assemble, as they rely on evanescent field coupling that necessitates close proximity of waveguides or significant tapering to facilitate optical energy transfer between separated waveguides.
Innovation Solution
A wavelength selective all-fiber coupler using graded index cores and optionally a slab core to spatially separate primary waveguides while maintaining strong optical coupling, allowing standard fibers to be spliced directly, with the graded index cores supporting only one wavelength transfer and enabling flexible, robust, and high-power operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If evanescent field coupling is used to transfer optical energy between waveguides, then optical coupling is achieved, but the waveguides must be placed very close together or heavily tapered, reducing robustness at high power
Solution Approach 1:
A third waveguide is introduced as an intermediary between the two signal waveguides. This intermediate waveguide facilitates optical energy transfer through a three-waveguide interaction mechanism that enables wavelength-selective coupling without requiring the signal waveguides to be in close proximity or heavily tapered, thereby maintaining robustness at high power while achieving effective optical coupling.
Solution Approach 2:
The invention utilizes wavelength as a controlling parameter to enable selective optical energy transfer. By designing the three-waveguide system with specific geometric and refractive index parameters, optical coupling occurs only at a predetermined wavelength, allowing the system to achieve both efficient coupling and high-power robustness through parameter optimization.
2Loss of energy
If waveguides are placed close together for evanescent coupling, then optical energy transfer is facilitated, but standard fibers cannot be directly spliced, requiring D-shaped fibers and multiple splices
Solution Approach 1:
The intermediate waveguide serves as a mediator that enables spatial separation of the signal waveguides. This separation allows each waveguide to be terminated with standard circular fibers that can be directly spliced, eliminating the need for D-shaped fibers and multiple splices while maintaining effective optical coupling through the three-waveguide interaction mechanism.
3Loss of energy
If conventional all-fiber couplers are used, then optical coupling is achieved, but they are not wavelength selective, unable to combine light of distinct wavelengths
Solution Approach 1:
The invention introduces wavelength selectivity by designing the three-waveguide system with specific geometric parameters and refractive index profiles. The coupling efficiency becomes a function of wavelength, with maximum transfer occurring only at a predetermined wavelength. This enables the coupler to selectively combine or separate wavelengths while maintaining efficient optical coupling.
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
Enables efficient, wavelength-selective transfer of optical energy between separated waveguides, allowing standard fibers to be used, reducing the risk of failure points and labor, while maintaining robustness at high powers and supporting multimode or single-mode operations.
Implementation Method 1
Existing all-fiber couplers are not wavelength selective and require heavy tapering or specialty fibers, making them unreliable for high-power applications and labor-intensive to assemble, as they rely on evanescent field coupling that necessitates close proximity of waveguides or significant tapering to facilitate optical energy transfer between separated waveguides.
Data Source
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AI summary
An all fiber wavelength selective coupler provides wavelength selective transfer of optical energy between two or more separated waveguides. The coupler includes signal cores that are separated enough that they can be fusion spliced to standard fibers as lead-in and lead-out pigtails. A bridge between the signal cores facilitates transfer of the optical energy through a process of evanescent coupling. In one example, the bridge is formed of a series of graded index cores.