High Peak Power Laser Pulse Generation with Reduced Speckle Contrast
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Solution Overview
Problem
Current systems for generating high peak power laser pulses face challenges in securely injecting and propagating these pulses through single-core fibers, especially in confined or hostile environments, due to damage thresholds and flexibility issues, leading to overcurrents and mechanical stress.
Innovation Solution
A system comprising a light source, a multimode fiber with a single core, a diffractive optical element, and a spatial shaping module that transforms the laser pulses into a 'top hat' intensity distribution with reduced speckle interference contrast, allowing secure injection and propagation while maintaining flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high peak power laser pulses are injected into optical fibers, then the power transmission capability is improved, but the fiber damage threshold is exceeded causing fiber deterioration
Solution Approach 1:
The invention divides the optical fiber into multiple independent cores within a single cladding structure. Each core can independently transmit high peak power laser pulses without exceeding the damage threshold of individual cores, while the aggregate power transmission capability of the multi-core fiber bundle meets the high power requirements. This segmentation approach distributes the power load across multiple channels, preventing any single core from experiencing damaging power densities.
Solution Approach 2:
The invention changes the structural parameters of the optical fiber by creating a multi-core configuration with specific core spacing and diameter ratios. By optimizing these geometric parameters, the system achieves both high aggregate power transmission and individual core power density control, resolving the contradiction between total power capability and individual core damage resistance.
2Adaptability or versatility
If optical fibers are used to access confined environments, then the accessibility to hostile locations is improved, but the fiber flexibility is reduced due to large core diameter requirements
Solution Approach 1:
The invention uses multiple small-core fibers bundled together within a single cladding, where each individual core has a small diameter that allows for flexible bending. The bundle as a whole provides the necessary aggregate core area for high power transmission, while individual core flexibility enables the fiber to navigate confined and hostile environments without excessive mechanical stress.
Solution Approach 2:
The invention transitions from a single large-core fiber to a multi-core bundle structure, effectively using the spatial arrangement dimension to resolve the contradiction. The small cores are distributed in a two-dimensional array within the cladding, allowing each core to remain flexible while the collective structure achieves the required power transmission capability.
3Power
If multiple optical fibers are used to increase power transmission, then the power capability is improved, but the system complexity and cost increase
Solution Approach 1:
The invention merges multiple cores within a single cladding structure to form an integrated multi-core fiber device. This unified structure behaves as a single optical component with standardized connectors and interfaces, eliminating the need for complex multi-fiber alignment systems. The merged structure provides aggregate power transmission capability while maintaining simple system architecture and reduced operational complexity.
Solution Approach 2:
The multi-core fiber structure serves multiple functions simultaneously: it provides high aggregate power transmission, maintains individual core flexibility, enables standard connector interfaces, and simplifies alignment requirements. This multi-functional design resolves the contradiction between power capability and system complexity by making the fiber device itself a universal solution that handles multiple requirements.
4Reliability
If large core diameter fibers are used to reduce damage risk, then the damage threshold safety is improved, but the fiber flexibility and bend resistance are worsened
Solution Approach 1:
The invention segments the total core area into multiple smaller cores, where each small core individually maintains high bend resistance and flexibility. The collective arrangement of these small cores within the cladding provides the necessary total light transmission area, ensuring that no single core experiences excessive bending stress while maintaining overall structural integrity and damage threshold safety.
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 system effectively reduces the contrast of high-frequency speckle-type interference, preventing overcurrents and damage, enabling secure and flexible transmission of high peak power laser pulses through single-core fibers.
Implementation Method 1
a diffractive optical element and an optical system arranged upstream of the fiber device, and configured to generate, from each of said initial laser pulses, a laser pulse at the input of the fiber device, the spatial intensity distribution of each of said laser pulses on an input face of said first multimode fiber comprising a low spatial frequency component of the 'top hat' type summed with a high spatial frequency component resulting from speckle type interference
Implementation Method 2
the spatial intensity distribution of each of said laser pulses on an input face of said first multimode fiber comprising a low spatial frequency component of the 'top hat' type summed with a high spatial frequency component resulting from speckle type interference
Implementation Method 3
a spatial shaping module, arranged upstream of the fiber device, configured to transform a first electric field into a second electric field formed from a sum of N components at least partially spatially incoherent with each other, N ≥ 2, such that the contrast of the high-frequency component resulting from the speckle-type interference is reduced
Implementation Method 4
a diffractive optical element and an optical system arranged upstream of the fiber device, and configured to generate, from each of said initial laser pulses, a laser pulse at the input of the fiber device
Implementation Method 5
an optical system arranged upstream of the fiber device, and configured to generate, from each of said initial laser pulses, a laser pulse at the input of the fiber device
Data Source
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AI summary
The present description relates to a system (200) for generating high peak power laser pulses, comprising a light source (240) for emitting initial nanosecond laser pulses (IL), a fibre-based device for transporting the laser pulses comprising at least a first multimode fibre (210) with a single core (212), a diffractive optical element (220) and an optical system (221) configured to generate, from each of the initial laser pulses, a laser pulse (IF), the spatial distribution of which, over an input face of the first multimode fibre, comprises a summed "top hat" component with a speckle figure. The system (200) further comprises a spatial shaping module (230) configured to convert a first electrical field into a second electrical field composed of a sum of N components at least partially spatially inconsistent with each other N ≥ 2, such that the contrast of the speckle figure is reduced relative to an initial contrast defined without a spatial shaping module.