Fiber Segments with Varying Core Diameters for Nonlinear Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fiber lasers and amplifiers face limitations in achieving high peak and average powers due to nonlinear effects such as Stimulated Brillouin Scattering, four-wave mixing, and amplified spontaneous emission, which restrict the output power and beam quality, especially when trying to scale up fiber sizes and lengths.
Innovation Solution
The use of fiber segments with varying core diameters and cladding diameters, where each segment is spliced together to divert amplified spontaneous emission and reduce nonlinear effects, allowing for co-propagating or counter-propagating pump light to optimize energy distribution and mode filtering, thereby enhancing beam quality and reducing unwanted signal interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fiber size and length are increased to achieve high output power, then power output is improved, but nonlinear effects such as Stimulated Brillouin Scattering and four-wave mixing increase
Solution Approach 1:
The fiber amplifier is divided into multiple segments with different core diameters. Each segment has optimized dimensions to control nonlinear effects locally while contributing to overall power amplification. The segmentation allows the system to achieve high output power without suffering from excessive nonlinear effects that would occur in a single long fiber.
Solution Approach 2:
Different segments of the fiber have different core diameters tailored to specific functions. Earlier segments have smaller cores to suppress nonlinear effects, while later segments have larger cores to handle higher power levels. This local optimization of fiber properties allows the system to simultaneously achieve high power output while maintaining control over nonlinear effects.
2Power
If fiber length is increased to amplify signal power, then power output is improved, but amplified spontaneous emission increases
Solution Approach 1:
The amplifier is segmented into multiple sections with varying core diameters. This segmentation allows the signal to be amplified in stages, with each segment contributing a portion of the total gain. By distributing the amplification across multiple segments rather than using a single long fiber, the accumulated amplified spontaneous emission is reduced while still achieving the desired signal power output.
3Object-generated harmful factors
If core diameter is increased to reduce nonlinear effects, then nonlinear effects are reduced, but beam quality deteriorates
Solution Approach 1:
Different segments have different core diameters optimized for their specific positions in the amplification chain. Earlier segments use smaller cores to maintain beam quality and suppress nonlinear effects, while later segments use larger cores to handle higher power levels. This spatial variation in core diameter allows the system to optimize both beam quality and nonlinear effect suppression at different stages of amplification.
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 approach increases the achievable output power to several hundred watts or kilowatts while maintaining good beam quality by minimizing nonlinear effects and efficiently managing pump power, allowing for more compact and reliable high-power fiber laser systems.
Implementation Method 1
nonlinear effects such as Stimulated Brillouin Scattering, four-wave mixing, and amplified spontaneous emission
Implementation Method 2
nonlinear effects such as Stimulated Brillouin Scattering, four-wave mixing, and amplified spontaneous emission
Implementation Method 3
co-propagating or counter-propagating pump light to optimize energy distribution and mode filtering
Data Source
AI summary
Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal cores for the signal and/or photonic-crystal inner cladding for the pump and/or use reflector connector segments. Some embodiments include an inner glass cladding to confine the signal in the core and an outer glass cladding to confine pump light in the inner cladding.