Multi-mode optical fiber transformers using long period gratings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical fiber mode converters can only operate with a single mode input and output, and cannot controllably change the mode of multiple modes simultaneously, limiting their functionality in applications requiring multiple mode transformations.
Innovation Solution
The development of an optical device and method using multiple mode transformers that can convert single mode inputs to multiple mode outputs or vice versa, with controllable power ratios, achieved through the use of long period gratings (LPGs) that adjust the refractive index of optical fibers, allowing for arbitrary mode conversion and redistribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single mode converter is used, then the device structure is simple, but it can only operate with single mode input and output, limiting functionality
Solution Approach 1:
The patent applies universality by designing a mode converter that can handle multiple input modes and produce multiple output modes simultaneously. The device uses multiple long period gratings with different characteristics to achieve multi-functional mode conversion, allowing it to convert between fundamental modes and higher order modes in both directions while maintaining a relatively integrated structure.
Solution Approach 2:
The patent segments the mode conversion function into multiple long period gratings, each responsible for specific mode transformations. By dividing the conversion task among several gratings with different periods and orientations, the device achieves complex multi-mode conversion capabilities while keeping each individual grating relatively simple.
2Adaptability or versatility
If multiple long period gratings are used for multi-mode conversion, then mode transformation functionality is enhanced, but device complexity increases
Solution Approach 1:
The patent merges multiple long period gratings into a single integrated device structure. The gratings are written into the same optical fiber core with different orientations and periods, combining their individual mode conversion functions into one unified device that achieves multi-mode transformation without requiring separate components.
Solution Approach 2:
The patent introduces dimensional diversity by writing gratings at different orientations (e.g., 0 degrees and 90 degrees) and different positions within the fiber core. This spatial dimensionality allows multiple gratings to coexist in the same fiber without excessive complexity, enabling independent mode conversion pathways.
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 conversion and redistribution of power between multiple modes, enhancing applications such as cladding-pumped devices by maximizing pump light intensity near the fiber core, and allowing for uniform mode distribution along the fiber cross-section, thereby improving pumping efficiency.
Implementation Method 1
long period gratings (LPGs) that adjust the refractive index of optical fibers
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The specification describes optical devices and related methods wherein an input mode is converted by multiple LPG mode transformers (1,2) to produce an output with multiple predetermined modes.