Multi-Pulse Amplification via Fiber Delay Modules
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Solution Overview
Problem
Chirped pulse amplification systems face challenges in generating multiple pulses with desired delays, as existing methods either require adjusting the oscillator cavity or result in increased system complexity and instability, particularly when using free space optics, and can lead to nonlinear interactions between pulses in the amplifier.
Innovation Solution
A chirped pulse amplification system that splits seed pulses into multiple pulses with controlled time delays, using fiber optics to apply a delay smaller than the stretched pulse duration, thereby reducing nonlinear interactions and maintaining collinear output, which is achieved by employing a splitter, delay module, amplifier, and compressor within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple pulses are generated using conventional CPA systems by adjusting the oscillator cavity or using free space optics, then multiple pulses with desired delays can be produced, but the system complexity increases and stability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the single seed pulse into multiple pulses using a pulse picker or acousto-optic modulator, which selects specific pulses from the oscillator train. This allows multiple pulses to be generated without redesigning the entire oscillator cavity, thereby reducing system complexity while maintaining multi-pulse generation capability.
Solution Approach 2:
The patent introduces an intermediary device (pulse picker or acousto-optic modulator) between the oscillator and amplifier stages. This intermediary selectively passes desired pulses while blocking others, enabling flexible multi-pulse generation without direct modification of the oscillator cavity, thus reducing overall system complexity and improving stability.
2Quantity of substance
If multiple pulses are generated with small delays using conventional methods, then dense pulse packs can be produced, but nonlinear interactions between pulses in the amplifier increase
Solution Approach 1:
The patent applies preliminary action by stretching each selected pulse in time before amplification using a stretcher device. This temporal stretching reduces the peak power of individual pulses, thereby minimizing nonlinear interactions during amplification while still allowing multiple stretched pulses to be amplified in sequence or parallel with controlled delays.
Solution Approach 2:
The patent utilizes periodic action by selecting pulses at regular intervals from the oscillator train using a pulse picker configured with a specific repetition rate. This periodic selection creates a controlled pulse train where the timing and spacing of pulses are predetermined, allowing optimization of delay intervals to minimize nonlinear interactions while maintaining desired pulse pack density.
3Use of energy by moving object
If the oscillator repetition rate is reduced to generate high energy pulses, then pulse energy increases, but the time delay between adjacent pulses increases to nanosecond to microsecond range
Solution Approach 1:
The patent applies dynamics by making the pulse selection process adjustable and flexible through programmable pulse pickers or acousto-optic modulators. The system can dynamically select different pulse intervals from the high-repetition-rate oscillator train, allowing optimization of the balance between pulse energy and time delay based on specific application requirements, rather than being fixed by the oscillator's inherent repetition rate.
Solution Approach 2:
The patent utilizes parameter changes by varying the selection criteria of the pulse picker or modulation frequency of the acousto-optic modulator. By changing these parameters, the system can select pulses at different intervals from the oscillator train, thereby controlling the output pulse energy and time delay independently of the oscillator's fixed repetition rate, enabling flexible optimization for different applications.
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 generates a dense pulse pack with controlled time delays between pulses, reducing nonlinear interactions and maintaining stability, while allowing for compact and environmentally stable laser design, enabling efficient amplification and recompression of pulses.
Implementation Method 1
a seed pulse is first stretched to longer pulse width τS by applying an optical group delay dispersion D(λ)
Implementation Method 2
The amplified pulses are then compressed back to ultrashort pulse width using the opposite group delay dispersion −D(λ)
Data Source
AI summary
Chirped pulse amplification (CPA) systems configured to generate and amplify multi-pulses are described. The nonlinear interaction of pulses can generate a multiple pulse pack with a dense time separation between pulses. Reducing or eliminating the nonlinear interaction can be provided by spectrally and/or temporally splitting pulses in the chirped amplification system.