Laser Resonator Fold-Mirrors for Non-Gaussian Pulse Shaping
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Solution Overview
Problem
Ultrafast MOPA systems require complex and costly pulse-shapers to shape seed-pulses into non-Gaussian spectra for improved pulse duration, which is unaffordable for institutions with limited budgets.
Innovation Solution
A laser resonator with a plurality of fold-mirrors, each coated with specific multilayer designs to impart predetermined group delay dispersion, generating spectra with non-Gaussian forms without the need for a pulse-shaper, achieving bandwidths at least 25% greater than Gaussian forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a pulse-shaper is used to shape the spectrum of seed-pulses into non-Gaussian forms, then the pulse duration is reduced and bandwidth is increased, but the device complexity and system cost increase significantly
Solution Approach 1:
The invention extracts the pulse shaping function from a separate external device (pulse-shaper) and integrates it into the laser resonator itself through specially coated mirrors. The mirrors with predetermined group delay dispersion coatings perform both the oscillation function and the spectral shaping function simultaneously, eliminating the need for external pulse-shaping equipment while achieving non-Gaussian spectral forms with broader bandwidth and shorter pulse duration.
Solution Approach 2:
The invention merges multiple functions into the laser resonator mirrors: the mirrors serve both as oscillation elements and as spectral shaping elements through their special coatings. By combining the oscillation function and pulse shaping function into a single integrated system, the patent eliminates the need for separate pulse-shaping devices, thereby reducing system complexity while achieving the desired non-Gaussian spectral output.
2Quantity of substance
If a pulse-shaper is used to shape the spectrum of seed-pulses, then the bandwidth is increased by almost twice the FWHM, but the system cost increases significantly
Solution Approach 1:
The invention extracts the spectral shaping capability from expensive external pulse-shaping equipment and embeds it directly into the laser resonator through specially coated mirrors. These mirrors with predetermined group delay dispersion provide the necessary spectral shaping to achieve broader bandwidth (almost twice the FWHM) without requiring separate, costly pulse-shaping devices.
Solution Approach 2:
The laser resonator mirrors are designed to automatically perform spectral shaping as part of their fundamental operation. The mirrors with special coatings inherently provide the group delay dispersion needed to generate non-Gaussian spectral forms with broader bandwidth, making the system self-sufficient and eliminating the need for additional expensive equipment.
3Duration of action of moving object
If traditional mirrors with negative group delay dispersion are used, then temporal broadening is minimized, but the spectrum remains essentially Gaussian with limited bandwidth
Solution Approach 1:
The invention applies different local qualities to different mirrors in the resonator. While traditional mirrors provide basic negative group delay dispersion to minimize temporal broadening, the patent introduces specific mirrors with predetermined group delay dispersion coatings designed to create non-Gaussian spectral forms. This localized functional differentiation allows simultaneous achievement of minimal temporal broadening and extended spectral bandwidth.
Solution Approach 2:
The invention changes the group delay dispersion parameter of specific mirrors from the conventional negative value to predetermined values that enable non-Gaussian spectral shaping. By carefully selecting mirrors with specific GDD characteristics, the system achieves both minimal temporal broadening and extended spectral bandwidth with non-Gaussian forms, resolving the trade-off between these two parameters.
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 solution allows for the generation of ultrafast pulses with extended bandwidths without the need for a pulse-shaper, reducing system costs while maintaining improved pulse duration and energy amplification efficiency.
Implementation Method 1
Selected ones of the fold-mirrors are coated with one of a plurality of multilayer coating designs, each thereof arranged to impart a predetermined group delay dispersion (GDD) as a function of wavelength to the fundamental radiation incident thereon
Implementation Method 2
A gain-element is located in the laser resonator. An arrangement is provided for optically pumping the gain-element, the optical pumping causing fundamental radiation to circulate in the laser-resonator
Implementation Method 3
The laser resonator is folded by a plurality of fold-mirrors on which the circulating radiation is incident a non-normal angle of incidence
Data Source
AI summary
An ultrafast laser for delivering ultra-short duration seed-pulses for further amplification has a resonator including negative group delay dispersion (NGDD) mirrors for minimizing increases in the duration of the pulses due to positive group delay dispersion effects inherent in the resonator. The NGDD mirrors could be configured such that the pulses had a Gaussian spectrum. Instead, however, the NGDD mirrors are configured and arranged such the pulses have a non-Gaussian spectrum. The non-Gaussian spectrum has a FWHM bandwidth significantly greater than that of the Gaussian spectrum.