Deep Ultraviolet Laser Generation via Cascaded Nonlinear Conversion
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Solution Overview
Problem
Current laser generation devices for deep ultraviolet (DUV) light at 213 nm face reliability issues due to degradation of nonlinear optical crystal elements caused by high photon energy ultraviolet light, particularly in continuous-wave operations, limiting output power and device lifespan.
Innovation Solution
A DUV laser generation device utilizing a thulium-doped laser source and an erbium/ytterbium-doped fiber source to generate near-infrared light through sum-frequency mixing, followed by second harmonic generation processes to produce blue light and ultimately DUV light at 213 nm, avoiding direct exposure of optical elements to high-energy ultraviolet light, thus reducing degradation and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power ultraviolet light is focused tightly onto the wavelength conversion element to increase output power, then the conversion efficiency is improved, but the degradation of the nonlinear optical crystal is accelerated
Solution Approach 1:
The patent divides the wavelength conversion process into multiple stages using different nonlinear optical crystals. The first crystal converts 1064 nm to 532 nm, the second converts 532 nm to 266 nm, and the third converts 266 nm to 213 nm. This segmentation allows each crystal to handle lower power densities individually, preventing degradation while achieving high output power through cascaded conversion.
Solution Approach 2:
The patent introduces intermediate wavelength conversion steps with intermediate crystals acting as mediators. Instead of directly converting 1064 nm to 213 nm in a single high-power step, the process uses 532 nm and 266 nm as intermediate wavelengths, with corresponding crystals handling lower power densities at each stage, thus protecting the nonlinear optical materials from damage.
2Productivity
If the wavelength conversion element is disposed into an optical resonator to increase light intensity for practical conversion efficiency, then the conversion efficiency is improved, but the optical loss from ultraviolet light absorption increases
Solution Approach 1:
The patent segments the optical resonator into multiple sections, each containing a different nonlinear crystal for specific wavelength conversion. This allows each resonator section to be optimized for its specific wavelength range, minimizing absorption losses while maintaining high conversion efficiency through resonant enhancement at each stage.
Solution Approach 2:
The patent changes the operating parameters of the optical resonator by using multiple resonators tuned to different wavelengths (1064 nm, 532 nm, 266 nm). Each resonator is optimized for its specific wavelength, ensuring maximum conversion efficiency while minimizing optical losses through parameter optimization at each conversion stage.
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 enables the production of high-output, reliable DUV laser light at 213 nm with extended device lifespan and improved stability, suitable for industrial applications such as semiconductor manufacturing and inspections.
Implementation Method 1
a first nonlinear wavelength conversion element for generating near-infrared light at a wavelength between 841 nm and 899 nm from the light at the first wavelength and the light at the second wavelength through a sum-frequency mixing (SFM) process
Implementation Method 2
a second nonlinear wavelength conversion element for generating blue light at a wavelength between 420 nm and 450 nm, from the near-infrared light through a second harmonic generation (SHG) process
Implementation Method 3
a third nonlinear wavelength conversion element for generating deep ultraviolet light at a wavelength between 210 nm and 225 nm from the blue light through an SHG process
Data Source
AI summary
In one embodiment, the present disclosure provides a deep ultraviolet laser generation device 1000 having a first laser source 100 at a first wavelength between 1.87 μm and 2.1 μm, a second laser source 200 at a second wavelength between 1.53 μm and 1.57 μm, a nonlinear wavelength conversion element 3 for generating near-infrared light 31 at a wavelength between 841 nm and 899 nm through a sum-frequency mixing (SFM) process, a nonlinear wavelength conversion element 4 for generating blue light 41 at a wavelength between 420 nm and 450 nm from the near-infrared light through a second harmonic generation (SHG) process, and a third nonlinear wavelength conversion element 5 for generating deep ultraviolet light 51 at a wavelength between 210 nm and 225 nm from the blue light, through another SHG process. The first laser source may be a thulium-doped laser source or a thulium-doped fiber source, and the second laser source may be a semiconductor laser source, an erbium-doped fiber source, or an erbium/ytterbium-doped fiber source.