Optical Fiber Terminal Structure for Coherent Mixer Alignment
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Solution Overview
Problem
In optical communications, the alignment errors between optical fibers and coherent mixer chips result in significant optical coupling losses due to the high precision required for pitch alignment, which is challenging with existing technologies, especially when using high-Δ waveguides that reduce mode field diameters and increase refractive index differences.
Innovation Solution
The optical fiber terminal structure incorporates high-Δ optical fibers with a capillary design where the high-Δ optical fibers are in contact with each other and fixed inside the capillary, allowing for precise alignment and reduced coupling losses by adjusting the core diameters and using a dummy fiber for stable, close-packed arrangements to minimize pitch errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If high-Δ waveguides are used to reduce waveguide size and increase relative refractive index difference, then waveguide confinement and downsizing are improved, but mode field diameter decreases and coupling loss increases
Solution Approach 1:
The patent introduces a mode field diameter conversion section as an intermediary component between the high-Δ waveguide and the optical fiber. This conversion section gradually transforms the mode field diameter from the small size in the high-Δ waveguide to the larger size in the standard optical fiber, enabling efficient coupling while maintaining the benefits of high-Δ waveguide confinement. The conversion section acts as a bridge that mediates the mismatch between the two different mode field diameters.
2Ease of manufacture
If conventional optical fibers are used with standard pitch tolerances, then ease of manufacture is improved, but alignment accuracy with high-precision optical elements deteriorates
Solution Approach 1:
The patent changes the pitch parameter of the optical fiber array to precisely match the pitch of the optical element ports. By carefully controlling and adjusting the pitch parameter during the fiber array fabrication process, the patent achieves accurate alignment with the optical element while maintaining ease of manufacture. This parameter adjustment allows the system to bridge the gap between conventional manufacturing tolerances and the high precision requirements of optical coupling.
Data Source
AI summary
An optical fiber terminal structure is comprised of a plurality of optical fibers, a plurality of high-Δ optical fibers connected to the optical fibers, respectively, and a capillary. The capillary has a hole in which the optical fibers and the high-Δ optical fibers are inserted, and the optical fibers and the high-Δ optical fibers together are fixed in the hole. Connection parts of each of the optical fibers and the high-Δ optical fibers are also positioned inside the capillary, and end surfaces of the high-Δ optical fibers are exposed so that adjacent high-Δ optical fibers are in contact with each other in an end surface of the capillary.