Fiber-Optic Burst Pulse Generation With Dispersion-Matched Arms
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Solution Overview
Problem
Current methods for generating femtosecond laser pulses with high micropulse repetition rates above 1 GHz face challenges in achieving high-quality burst operation, particularly in compact and robust fiber-optic setups that can be integrated into amplifiers, due to issues with pulse duration variation and interference in free beam propagation setups.
Innovation Solution
The use of fiber-optic components with different dispersions in the arms of a Mach-Zehnder interferometer-like setup, where laser pulses are split and delayed, ensuring minimal dispersion differences and almost identical pulse durations across the burst, achieved by coordinating optical fibers in terms of dispersion and length to maintain phase coherence across fiber arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If free beam propagation setup with birefringent crystals is used for pulse splitting, then high micropulse repetition rates can be achieved, but the setup is susceptible to interference and lacks compactness
Solution Approach 1:
The patent replaces the free beam propagation setup with mechanical birefringent crystals with a fiber-optic implementation using fiber optic beam splitters and delay lines. This substitution eliminates the interference susceptibility of free-space optics while maintaining the pulse splitting functionality and high micropulse repetition rates, achieving both reliability and speed requirements.
2Device complexity
If fiber optic cascading of beam splitters is used, then compact and robust setup is achieved, but dispersion compensation is not provided resulting in pulse duration variation
Solution Approach 1:
The patent applies local quality by introducing dispersion compensation specifically in the longer fiber arms of the Mach-Zehnder interferometer setup. By adding dispersion compensating fibers or modules at specific locations (in the longer arms), the patent maintains compact fiber-optic architecture while locally correcting the dispersion-induced pulse duration variation, thus achieving both compactness and pulse duration consistency.
3Productivity
If high average power is used in equidistant pulse spacing, then productivity is improved, but heat input causes damaging effects on workpiece
Solution Approach 1:
The patent implements periodic action by organizing laser pulses into bursts with intraburst micropulse sequences separated by longer interburst intervals. This periodic structure allows high average power delivery through the密集 micropulse sequences while the longer intervals between bursts enable heat dissipation, preventing cumulative heat damage to the workpiece and maintaining both productivity and reducing harmful thermal effects.
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 allows for the generation of high-quality laser pulses with sufficient micropulse repetition rates and consistent pulse durations, enabling efficient and robust burst operation suitable for high-precision material processing, even at high average power levels, by minimizing heat input and preventing damage to the workpiece.
Implementation Method 1
the optical fibers of the fiber arms are matched to one another with regard to dispersion and length in such a way that the laser pulses supplied to the combining element via the fiber arms differ from one another with regard to the chirp generated by the respective dispersion
Implementation Method 2
a fiber optic combiner element that superimposes the laser pulses supplied to the combiner element via the at least two fiber arms in a burst
Data Source
Figure 1~3
AI summary
The invention relates to an optical component for generating laser pulses with a time offset, having a fibre-optic dividing element (3) by means of which a laser pulse (1) entering the dividing element via an input fibre is divided between at least two fibre arms (5, 6), and a fibre-optic combination element (4) by means of which the laser pulses entering the combination element via the at least two fibre arms (5, 6) are combined in an output fibre, wherein the at least two fibre arms (5, 6) have a length difference so that the laser pulses are combined in a burst (2) with a time offset by the fibre-optic combination element (4) in the output fibre. The problem addressed by the invention is that of finding a way to generate high-quality laser pulses in burst mode using the principle of pulse dviding, which can be implemented in a compact and robust manner and as far as possible by means of fibre optics. The invention solves this problem in that the fibre arms (5, 6) are formed by optical fibres which have different dispersions. The invention also relates to a device and a method for generating laser pulses in a burst mode.