Fiber Delivery of Short Laser Pulses via Temporal Stretching
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Solution Overview
Problem
Existing methods for delivering short laser pulses over longer distances in optical fibers result in poor pulse quality due to nonlinear effects and dispersion, leading to significant energy being contained in satellite pulses rather than the main peak, which can saturate nonlinear media and hinder efficient recompression.
Innovation Solution
The method involves generating and amplifying laser pulses, followed by temporal stretching and propagation through an optical delivery fiber where the pulses undergo nonlinear spectral broadening, increasing the spectral bandwidth by at least a factor of 1.2, and using a combination of fiber types to achieve efficient compression and minimize third-order dispersion, ensuring a larger portion of energy is in the main peak and reducing sensitivity to dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If laser pulses are transmitted through optical fiber over longer distances, then delivery distance is improved, but pulse quality deteriorates due to nonlinear effects and dispersion
Solution Approach 1:
The patent applies preliminary action by performing temporal stretching of laser pulses before they enter the optical delivery fiber. This pre-stretching reduces the peak power and pulse intensity, which prevents nonlinear effects from degrading pulse quality during transmission over long distances. The pulses are then recompressed at the output to restore their original duration, achieving both long delivery distance and high pulse quality.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the temporal characteristics of laser pulses through stretching and compressing. The pulse duration is changed from its original short duration to a stretched duration during transmission, and then back to the original duration at the output. This parameter transformation allows the system to overcome the trade-off between delivery distance and pulse quality.
2Object-generated harmful factors
If temporal stretching is applied to reduce peak power, then nonlinear effects are reduced, but satellite pulses are generated at the fiber output
Solution Approach 1:
The patent applies parameter changes by carefully controlling the stretching factor and fiber length to optimize the balance between reducing nonlinear effects and minimizing satellite pulse generation. By adjusting these parameters, the system achieves sufficient peak power reduction while maintaining acceptable pulse shape quality at the output.
Solution Approach 2:
The patent uses spectral broadening in highly nonlinear fiber to create a copied or enhanced version of the pulse spectrum with increased bandwidth. This spectral copying approach allows for better compression performance and reduced satellite pulses by providing a more favorable spectral profile for the compression process.
3Duration of action of moving object
If solitonic compression is used to compress laser pulses, then pulse duration is reduced, but spectral shape becomes strongly modulated causing complex phase profile
Solution Approach 1:
The patent extracts or removes the problematic spectral modulations and complex phase profiles that arise from conventional solitonic compression. By using an alternative compression approach based on temporal stretching followed by controlled propagation in optical fiber, the system achieves pulse compression without generating the harmful spectral and phase complexities associated with traditional solitonic methods.
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 achieves improved pulse shape and quality at the delivery point with a significant increase in the spectral bandwidth, allowing for a pulse duration of less than 100 fs with over 90% of energy in the main peak, reducing sensitivity to third-order dispersion, and is suitable for longer delivery distances.
Implementation Method 1
The optical delivery fiber introduces a dispersion which compensates for the dispersion introduced by the pulsed laser source and the stretcher, such that a recompressed optical pulse is delivered to the application
Implementation Method 2
wherein the laser pulses are temporally compressed in the optical delivery fiber and wherein the laser pulses undergo nonlinear spectral broadening in the optical delivery fiber
Implementation Method 3
During the following compression self-phase modulation (SPM) proportional to the temporal shape of the laser pulses causes a complex phase profile that prevents an efficient recompression
Data Source
AI summary
A method and system for delivering laser pulses achieves the delivery of high quality laser pulses at the location of an application. The method includes the steps of: generating laser pulses, amplifying the laser pulses, temporally stretching the amplified laser pulses, and propagating the amplified laser pulses through an optical delivery fiber of desired length, wherein the laser pulses are temporally compressed in the optical delivery fiber and wherein the laser pulses undergo nonlinear spectral broadening in the optical delivery fiber.