Optical Pulse Combining Arrangement for Higher Pulse Energy

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Solution Overview

Problem

Pulsed laser systems face limitations in pulse energies, peak pulse powers, and average power due to physical and technical constraints, such as component destruction from high intensities and nonlinear effects like self-phase modulation, which existing methods like Chirped Pulse Amplification, circular polarization, spatial and temporal pulse division, and resonators attempt to address but often require a significant increase in optical components.

Innovation Solution

An optical arrangement where temporally successive pulses from a laser system are directly combined into a single pulse without initial splitting, using spatially separated partial beams with phase modulation and optical delay paths to achieve temporal overlap and phase matching, reducing the need for additional components and enhancing pulse energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If temporal pulse division and combination is used to increase pulse energy, then pulse energy can exceed component limitations, but the number of optical components increases significantly

Engineering Contradiction:
Improvepulse energyVSAvoidnumber of optical components
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The pulse train is divided into multiple temporally separated pulses using a pulse picker, which selects specific pulses from the original train. This segmentation allows individual pulses to be processed and then combined to achieve higher pulse energy while maintaining system simplicity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple temporally separated pulses are combined into a single high-energy pulse using a non-linear optical crystal through four-wave mixing. This merging process accumulates the energy of multiple pulses into one, achieving the desired pulse energy enhancement without requiring complex component assemblies

Inventive Principle:
Principle #5Merging (Combining)

2Object-affected harmful factors

If peak intensity is reduced by enlarging the pulse or beam, then component destruction is avoided, but pulse energy and power are reduced

Engineering Contradiction:
Improvecomponent destructionVSAvoidpulse energy
Core Design Contradiction:
Object-affected harmful factorsVSPower

Solution Approach 1:

A pulse train with multiple pulses at reduced individual intensity is generated, and then specific pulses from this train are selected and combined. The periodic structure of the pulse train allows selective pickup of pulses that have been amplified without suffering from the intensity limitations of single-pulse systems

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The temporal parameters of the pulse train are manipulated by selecting specific pulses with a pulse picker and combining them with different time delays. This changes the temporal distribution of energy while maintaining the amplified energy level, achieving high pulse energy without the component destruction associated with high peak intensity

Inventive Principle:
Principle #35Parameter changes

3Productivity

If active stabilization is used to adjust path lengths for better combination efficiency, then pulse combination efficiency improves, but system complexity and number of control elements increase

Engineering Contradiction:
Improvecombination efficiencyVSAvoidnumber of control elements
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The optical path lengths are pre-adjusted during system setup to account for the time delays between consecutive pulses in the pulse train. This preliminary adjustment ensures that when pulses are combined, they are already properly synchronized, eliminating the need for complex active stabilization systems with multiple control elements

Inventive Principle:
Principle #10Preliminary action

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 effectively increases pulse energy by minimizing the number of optical components required, improving combination efficiency and overcoming limitations in pulse parameters, while actively controlling phase patterns to compensate for time-varying differences and dispersion effects.

Implementation Method 1

The two partial beams are combined in a non-linear optical crystal through four-wave mixing, so that a sequence of temporally separated pulses is combined into a single pulse

Methodology Applied
Scientific EffectFour-wave mixing:

Implementation Method 2

at least one phase adjustment element is provided in each partial beam—which is before or after the optical element—that influences the phase of the radiation of at least one partial beam

Methodology Applied
Scientific EffectPhase modulation: Phase Modulation

Data Source

PatentEP3394938B1Optical arrangement
Publication Date: 2024.06.19 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3394938B1 patent drawingFigure 1~2
  • EP3394938B1 patent drawingFigure 3
  • EP3394938B1 patent drawingFigure 4

AI summary

The invention relates to an optical arrangement having - a division element which divides an input beam consisting of a sequence of temporally equidistant light pulses into two spatially separate partial beams, - at least one optical element through which at least one of the partial beams propagates, and - at least one combination element which spatially superimposes the partial beams in an output beam. The problem addressed by the invention is that of showing a method for increasing the pulse energy of light pulses which is improved in comparison with the prior art. The invention solves this problem by virtue of the fact that the combination element superimposes a number of the temporally successive light pulses in a single light pulse in the output beam. The invention also relates to a method for increasing the pulse energy of light pulses.