Gradient Index Lens for VCSEL to Fiber Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing optical signal transmission systems face a mode field diameter mismatch between lasers and optical fibers, particularly between surface-emitting lasers like VCSELs and single-mode optical fibers, leading to low coupling efficiency due to differences in mode field diameters.
Innovation Solution
An apparatus with an optical signal transmission part that gradually changes refractive index, allowing for optical signal convergence or divergence to match the mode field radius of the laser with the core radius of the optical fiber, thereby enhancing coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light is emitted directly from VCSEL to single-mode optical fiber, then the structure is simple, but the mode field diameter mismatch causes low coupling efficiency
Solution Approach 1:
The patent introduces an optical signal transmission part with gradient refractive index as an intermediary component between the VCSEL and single-mode optical fiber. This gradient index structure acts as a mode field adapter that transforms the large mode field diameter from the VCSEL to match the small core diameter of the single-mode fiber, thereby resolving the mode field mismatch problem while maintaining reasonable structural complexity
Solution Approach 2:
The patent employs parameter changes by designing an optical transmission medium with gradually changing refractive index. The refractive index varies continuously from the center to the periphery of the gradient index structure, enabling controlled transformation of the optical mode field diameter. This parameter variation allows efficient coupling between VCSEL and single-mode fiber without requiring complex alignment mechanisms
2Speed
If conventional electrical interconnection is used, then the structure is simple, but the connection size is very small causing electrical interconnection delay greater than component running speed
Solution Approach 1:
The patent replaces the conventional electrical interconnection system with an optical interconnection system. By substituting electrical signals with optical signals, the system achieves transmission speeds that exceed component running speeds, eliminating the bottleneck inherent in electrical interconnection while managing the increased structural complexity through integrated optical components
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 effectively adjusts the optical signal to match the fiber core diameter, significantly improving coupling efficiency and minimizing reflection, thus enabling high-efficiency optical signal transmission.
Implementation Method 1
an optical signal transmission part, a refractive index of which changes gradually
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention discloses an apparatus for coupling a laser and an optical fiber and an optical signal transmission system and transmission method. An coupling apparatus is disposed between a laser and an optical fiber, where the coupling apparatus includes an optical signal transmission part whose inner refractive index changes gradually, where a refractive index becomes higher at a position closer to a principal axis of the optical signal transmission part; and the optical signal transmission part may be configured to shape an optical signal incident from the laser (including optical signal convergence or divergence), so that a mode field radius of the adjusted optical signal matches a core radius of the optical fiber, and the adjusted optical signal can be coupled into the optical fiber in high efficiency.