Pulse-Shaped Multi-Pass Wavelength Conversion for High-Power Lasers
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Solution Overview
Problem
Conventional methods for wavelength conversion of laser pulses face limitations in power handling, efficiency, and frequency tuning, particularly in extending high-power femtosecond source technology to broader wavelength regions, with existing techniques suffering from low efficiency or limited power compatibility.
Innovation Solution
A wavelength conversion apparatus and method utilizing a multi-pass cell with an optically non-linear Kerr medium and a pulse shaper device to create non-symmetrical temporal pulse shapes, enabling self-phase modulation and efficient spectral broadening, which shifts the center wavelength of laser pulses while maintaining high power handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional frequency shifting approaches using Stimulated Raman Scattering (SRS) in optical fibers are used, then wavelength conversion is achieved, but power handling capability is limited to low power levels
Solution Approach 1:
The patent applies asymmetry by creating non-symmetrical temporal pulse shapes with different leading and trailing flank steepness. This asymmetric pulse shaping enables directional spectral shifting (blue or red) through self-phase modulation in the multi-pass cell, resolving the contradiction by allowing efficient wavelength conversion at high power levels without the limitations of conventional SRS methods
2Adaptability or versatility
If spectral broadening with multi-pass cell is combined with band pass filter, then selected bandwidth can be obtained, but pulse energy efficiency is very low as only a small portion of pulse energy is used
Solution Approach 1:
The patent extracts only the necessary spectral components through asymmetric pulse shaping that directs energy preferentially toward the desired wavelength region. By using non-symmetrical pulse shapes with controlled flank steepness, the system extracts the required frequency range while minimizing energy loss, avoiding the inefficiency of filtering only a small portion of broadened spectral content
3Adaptability or versatility
If conventional parametric frequency conversion in Optical Parametric Amplifiers (OPAs) is used, then wide spectral coverage is provided, but power handling capability and efficiency are limited
Solution Approach 1:
The patent substitutes the mechanical/optical complex system of OPAs with a simpler multi-pass cell configuration using self-phase modulation. By replacing the OPA's parametric conversion mechanism with asymmetric pulse shaping and Kerr medium-based SPM, the system achieves wide spectral coverage while maintaining high average power handling capability that OPAs cannot provide
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 achieves efficient spectral conversion with increased peak and average power, facilitates frequency tuning across extended ranges, and improves temporal pulse quality, enabling access to wavelength regions not easily accessible with existing ultrafast laser platforms.
Implementation Method 1
the new spectral components of the laser pulses are created by self-phase modulation
Implementation Method 2
a multi-pass cell device including an optically non-linear Kerr medium
Data Source
Figure 1~3
Figure 4A~5
Figure 6~8
AI summary
A wavelength conversion apparatus 100 for spectrally converting laser pulses 1 by creating new spectral components 2 of the laser pulses 1 comprises a multi-pass cell device 10 including an optically non-linear medium 11 and being arranged for receiving the laser pulses 1 to be converted and transmitting the laser pulses 1 through the optically non-linear medium 11 multiple times, wherein the new spectral components 2 of the laser pulses 1 are created by self-phase modulation, and a pulse shaper device 20 being arranged upstream of the multi-pass cell device 10 and being capable of changing the spectral phase and/or the amplitude of the laser pulses 1 for providing the laser pulses 1 to be converted with a non-symmetrical temporal pulse shape 3 having a leading flank 4 and a trailing flank 5 with different amounts of steepness, wherein the non-symmetrical temporal pulse shape 3 yields a centre wavelength shift of the laser pulses 1 by the self-phase modulation in the multi-pass cell device 10. Furthermore, a laser source apparatus 200 including the wavelength conversion apparatus and a wavelength conversion method for spectrally converting laser pulses 1 are described.