Expanded-beam ferrule with aspheric lens for misalignment tolerance
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Solution Overview
Problem
Optical fiber connectors face challenges with contamination sensitivity and misalignment issues, leading to degraded data transmission and reduced coupling efficiency, especially in expanded-beam connectors which require precise alignment and are sensitive to lateral and angular misalignments.
Innovation Solution
The design of an expanded-beam optical interface device featuring transparent support members with axially aligned, convex aspheric lenses that have specific conic constants and on-axis spherical aberration ranges, supporting optical fibers in a manner that tolerates misalignments and enhances coupling efficiency by ensuring substantial off-axis light is coupled into the fiber core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical-contact connectors are used to join optical fibers, then the connection provides mechanical stability and alignment, but the connector becomes sensitive to contamination and requires precise alignment maintaining high manufacturing precision
Solution Approach 1:
The patent introduces an expanded beam optical path as an intermediary between the two fiber ends. Instead of direct physical contact, light is expanded by the first lens, travels through air (avoiding contamination), and is focused by the second lens onto the receiving fiber. This intermediary optical path eliminates the need for direct fiber-to-fiber contact, thereby eliminating contamination sensitivity while maintaining connection stability.
2Object-affected harmful factors
If expanded-beam connectors are used to avoid physical contact, then contamination sensitivity is reduced, but misalignment tolerance remains poor requiring high manufacturing precision
Solution Approach 1:
The patent changes the optical parameters by using aspheric lens surfaces with specific conic constants (k=-1 and k=-6) and controlled spherical aberrations. These parameter changes in the lens design create an expanded beam profile that is inherently more tolerant to lateral and angular misalignments, reducing the precision requirements for connector assembly while maintaining low contamination sensitivity.
3Loss of energy
If conventional lenses are used in expanded-beam connectors, then the optical path is established, but coupling efficiency is reduced due to spherical aberration and misalignment sensitivity
Solution Approach 1:
The patent employs aspheric lens surfaces with specific conic constants instead of conventional spherical lenses. The first lens has a conic constant of k=-1 and the second lens has k=-6, creating optimized curvature profiles that reduce spherical aberration. This improved curvature design ensures that off-axis light rays are properly focused onto the fiber core, significantly reducing coupling loss and improving coupling efficiency while maintaining misalignment tolerance.
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 significantly reduces coupling loss and improves misalignment tolerance, maintaining high coupling efficiency even with lateral and angular offsets, compared to conventional designs, by effectively focusing off-axis light into the optical fiber core.
Implementation Method 1
first and second lenses have respective first and second front surfaces and first and second back surfaces, and wherein each of the first and second front lens surfaces is convex and aspheric
Implementation Method 2
ensuring substantial off-axis light is coupled into the fiber core
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~2
AI summary
An expanded-beam ferrule for an optical interface device has a ferrule body with a fiber support feature that supports an optical fiber. The ferrule body defines a lens having a planar back surface and a convex and aspheric front surface. The lens has a select amount of on-axis spherical aberration that gives rise to an improved coupling efficiency and in particular provided tolerance to misalignments between confronting expanded-beam ferrules used in an expanded-beam optical interface device. The ferrule body can also include multiple lenses and can support multiple optical fibers in operable alignment thereto.