Amplification Optical Fiber Core Segmentation for Non-Linear Effect Suppression
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Solution Overview
Problem
Amplification optical fibers that use double clad fibers with active elements distributed according to higher order mode intensity profiles often experience non-linear optical effects due to high light density, leading to reduced power output and beam quality issues, especially when bent.
Innovation Solution
The amplification optical fiber is designed with a higher order mode such as the LP02 or LP03 mode, where the active element is concentrated in regions with stronger intensity profiles, suppressing non-linear effects and maintaining power output even when bent, by satisfying specific concentration and amplification factor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the core propagates only single mode light to maintain beam quality, then the cross-sectional area of the core is small, but the light density becomes too high causing non-linear optical effects
Solution Approach 1:
The core is divided into multiple regions (first region with higher active element concentration and second region with lower active element concentration) to create different amplification zones. This segmentation allows the fiber to amplify higher order modes in the first region while suppressing LP01 mode amplification in the second region, thereby preventing non-linear optical effects while maintaining beam quality.
Solution Approach 2:
Different regions of the core are assigned different active element concentrations to achieve different amplification characteristics. The first region has higher concentration to amplify higher order modes, while the second region has lower concentration to suppress LP01 mode, creating local quality variations that resolve the contradiction between beam quality and non-linear effects.
2Ease of operation
If the amplification optical fiber is bent to improve flexibility and ease of operation, then the light distribution changes and mode field is distorted, but the non-linear optical effect occurs more easily
Solution Approach 1:
The segmented core structure with different active element concentrations creates a more robust mode distribution that is less sensitive to bending. The first region's higher concentration amplifies higher order modes that are less affected by bending, while the second region suppresses LP01 mode that would be distorted by bending, maintaining performance under flexible conditions.
Solution Approach 2:
Instead of trying to prevent bending, the invention inverts the approach by designing a core that actively suppresses the LP01 mode (which is most affected by bending) while amplifying higher order modes. This inversion strategy makes the fiber performance less dependent on maintaining perfect straight alignment.
3Power
If the active element is distributed according to higher order mode intensity profile to amplify higher power, then the LP01 mode is also amplified at high factor, but the light density becomes too high at center causing non-linear optical effect
Solution Approach 1:
The core is segmented into two regions with different active element concentrations. The first region has higher concentration to provide high amplification for higher order modes, while the second region has lower concentration to suppress LP01 mode amplification. This prevents excessive light density concentration at the center that would cause non-linear optical effects.
Solution Approach 2:
Different local regions have different active element concentrations optimized for different functions. The first region (with higher concentration) is optimized for high-power amplification of higher order modes, while the second region (with lower concentration) is optimized for suppressing LP01 mode, creating local quality differences that resolve the power vs. non-linear effect contradiction.
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
This configuration allows for higher power light emission with improved beam quality and reduced non-linear optical effects, ensuring desired power output and stability across different modes and fiber orientations.
Implementation Method 1
an active element such as a rare-earth element is added in a core
Implementation Method 2
an optical energy is transited to an undesired wavelength by a non-linear optical effect
Data Source
Figure 1~2
Figure 3A~3D
Figure 4A~4D
AI summary
Provided are an amplification optical fiber which is capable of emitting light having a desired power and an optical fiber amplifier and a resonator using the same. An amplification optical fiber 50 includes a core 51 and a clad 52 which covers the core 51. The core 51 propagates light having a predetermined wavelength in at least an LP01 mode, an LP02 mode, and LP03 mode and, in the core 51, when the LP01 mode, the LP02 mode, and the LP03 mode are standardized by a power, in at least a part of a region where an intensity of at least one of the LP02 mode and the LP03 mode is stronger than an intensity of the LP01 mode, an active element which stimulates and emits light having a predetermined wavelength is added with a higher concentration than that in at least a part of a region where the intensity of the LP01 mode is stronger than the intensities of the LP02 mode and the LP03 mode.