Multimode Optical Amplifier Gain Flattening Across Modes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multimode optical amplifiers face a challenge in reducing inter-mode gain deviation due to varying electric field intensity distributions in optical fibers, leading to power differences and limited transmission distances in long-haul mode division multiplexing systems, with existing solutions increasing manufacturing costs and complexity.
Innovation Solution
A multimode optical amplifier configuration that includes a multiplexer, amplifying fiber, wavelength-flattening filter, and mode-flattening filter to provide uniform gain across multiple propagation modes, using a multiplexer to combine signal and excitation light, and filters to maintain constant gain values regardless of frequency or mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a multimode optical amplifier uses a single amplifying fiber, then the device complexity and manufacturing cost are reduced, but the inter-mode gain deviation increases due to varying electric field intensity distributions
Solution Approach 1:
The patent introduces a mode coupling element as an intermediary component between the amplifying fiber and the output. This mode coupling element transforms the signal modes into a configuration where gain equalization can be achieved, mediating between the non-uniform gain of the single amplifying fiber and the desired uniform gain across all modes without requiring multiple different fiber types
Solution Approach 2:
The patent changes the coupling parameter between modes by introducing a specific mode coupling length and coupling coefficient. By adjusting these parameters, the signal undergoes mode transformation that equalizes the gain across different propagation modes, converting the non-uniform gain distribution into a uniform one through controlled parameter modification
2Manufacturing precision
If different kinds of amplifying multimode fibers are combined to reduce inter-mode gain deviation, then the gain uniformity improves, but the manufacturing cost and device complexity increase
Solution Approach 1:
The patent merges the functions of multiple different amplifying fibers into a single amplifying fiber by introducing a mode coupling mechanism. Instead of combining multiple physical fibers with different properties, the mode coupling element effectively combines the mode transformations that would occur in different fiber types, achieving the same gain equalization effect within a single fiber structure
Solution Approach 2:
The single amplifying fiber is made multi-functional through the mode coupling element. The same amplifying fiber can now serve multiple modes with different electric field distributions uniformly, making it universal for amplifying all modes equally. The mode coupling element enables the single fiber to perform the function that previously required multiple specialized fibers
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 flattens gain across multiple modes, reducing inter-mode gain deviation and maintaining consistent optical power, thereby extending transmission distances and simplifying the amplifier configuration while reducing manufacturing costs.
Implementation Method 1
an amplifying fiber which has a core that propagates a predetermined plurality of propagation modes of the signal light and a predetermined plurality of propagation modes of the excitation light, and which provides an individual gain value for each of the predetermined propagation modes of the signal light
Implementation Method 2
a multiplexer that multiplexes the signal light and excitation light
Implementation Method 3
a wavelength-flattening filter that maintains a constant gain value for a frequency for all predetermined propagation modes of the signal light
Implementation Method 4
a mode-flattening filter that maintains the gain value at a constant value for a predetermined propagation mode of the signal light for all predetermined propagation modes of the signal light
Data Source
AI summary
There is provided a multimode optical amplifier that provides gain to a plurality of propagation modes of signal light. The multimode optical amplifier includes a multiplexer that multiplexes the signal light and excitation light; an amplifying fiber which has a core that propagates a predetermined plurality of propagation modes of the signal light and a predetermined plurality of propagation modes of the excitation light, and which provides an individual gain value for each of the predetermined propagation modes of the signal light; a wavelength-flattening filter that maintains a constant gain value for a frequency for all predetermined propagation modes of the signal light; and a mode-flattening filter that maintains the gain value at a constant value for a predetermined propagation mode of the signal light for all predetermined propagation modes of the signal light.