Wavelength Conversion Timing in Solid-State Laser Systems
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Solution Overview
Problem
In semiconductor exposure apparatuses, the narrow spectrum line width of laser beams is difficult to achieve due to stimulated Brillouin scattering in fiber amplifiers, particularly for wavelengths like 1554 nm, which hampers the amplification of pulse energy and subsequently affects the wavelength conversion efficiency in solid-state laser systems.
Innovation Solution
The second pulse laser beam is made to incident on the second non-linear crystal before the first pulse laser beam, with residual light from the second pulse beam being directed to the first non-linear crystal later, optimizing the timing to enhance the wavelength conversion efficiency by reducing the delay and intensity loss of the second pulse laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the second pulse laser beam is made to incident on the second non-linear crystal before the first pulse laser beam, then the wavelength conversion efficiency is improved, but the timing control complexity increases
Solution Approach 1:
The second pulse laser beam is advanced in time to incident on the second non-linear crystal before the first pulse laser beam arrives at the first non-linear crystal. This preliminary action ensures that the second beam is ready for wavelength conversion earlier, optimizing the temporal sequence for maximum conversion efficiency while managing the complexity through deliberate timing design.
2Productivity
If residual light from the second pulse beam is directed to the first non-linear crystal later, then the use efficiency of the second pulse laser beam is improved, but the temporal distribution of energy becomes more complex
Solution Approach 1:
Instead of discarding the residual light from the second pulse laser beam after it passes through the second non-linear crystal, the invention directs this residual light to the first non-linear crystal for further wavelength conversion. This recovers otherwise wasted energy and improves the overall use efficiency of the second pulse laser beam, transforming what would be loss into useful output.
3Loss of energy
If the timing delay between pulse beams is reduced, then the wavelength conversion efficiency is improved, but the risk of stimulated Brillouin scattering increases
Solution Approach 1:
The second pulse laser beam is advanced in time to incident on the second non-linear crystal before the first pulse laser beam reaches the first non-linear crystal. This preliminary timing arrangement reduces the delay between beams, improving wavelength conversion efficiency by ensuring both beams are present and ready for conversion with minimal temporal separation, thereby maximizing energy utilization.
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 improves the use efficiency of the second pulse laser beam and reduces the decrease in wavelength conversion efficiency, leading to a more effective generation of the fourth pulse laser beam with a wavelength of 193.4 nm.
Implementation Method 1
configured to perform wavelength conversion of the first pulse laser beam and the second pulse laser beam into a third pulse laser beam having a third wavelength through a sum frequency generation process
Implementation Method 2
the narrow spectrum line width of laser beams is difficult to achieve due to stimulated Brillouin scattering in fiber amplifiers
Data Source
AI summary
A solid-state laser system includes: a first solid-state laser device configured to output a first pulse laser beam; a second solid-state laser device configured to output a second pulse laser beam; a first non-linear crystal disposed on a first optical path and configured to convert the first and second pulse laser beams into a third pulse laser beam and output the third pulse laser beam; and a second non-linear crystal disposed on a second optical path and configured to convert the second and third pulse laser beams into a fourth pulse laser beam and output the fourth pulse laser beam. The second pulse laser beam is incident on the second non-linear crystal at a first timing before the first non-linear crystal. Residual light of the second pulse laser beam is incident on the first non-linear crystal at a second timing later than the first timing.