Two-Stage Pumped DUV Laser for Coherent Short-Wavelength Output
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Solution Overview
Problem
Current deep ultraviolet (DUV) lasers have limitations due to large space volume, high manufacturing cost, and low efficiency of non-linear effects, which restrict their ability to produce coherent photons and limit the minimum photon wavelength to 114 nm.
Innovation Solution
A laser design that incorporates a medium with a ground state, intermediate state, and excited state, utilizing an excitation system and an excitation laser for stimulated emission to generate coherent photons, allowing for two pumping processes to achieve a compact and cost-effective DUV laser with shorter wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-linear effects are used to generate DUV lasers from fundamental lasers, then short-wavelength photons can be produced, but the efficiency is low requiring high-power fundamental lasers which result in large space size and high manufacturing cost
Solution Approach 1:
The patent replaces the conventional non-linear optical conversion mechanism with a direct electromagnetic field excitation mechanism. Instead of using high-power fundamental lasers and non-linear crystals to generate DUV photons, the invention uses an electromagnetic field excitation system to directly excite helium atoms, which then emit DUV photons through spontaneous emission. This substitution eliminates the need for complex non-linear optical systems and high-power laser generators, thereby reducing both space size and manufacturing cost while improving power efficiency.
Solution Approach 2:
The patent changes the excitation parameter from optical field excitation (using fundamental lasers) to electromagnetic field excitation (using electromagnetic fields). This parameter change enables direct excitation of helium atoms to the 1s2p state, which then decay to ground state emitting DUV photons. This fundamental parameter change in the excitation mechanism achieves DUV laser generation with much lower power requirements and smaller system size.
2Power
If non-linear effects are used to generate DUV lasers, then short-wavelength photons can be produced, but the manufacturing cost is high
Solution Approach 1:
The patent replaces the expensive non-linear optical conversion system with a simple electromagnetic field excitation system. The conventional approach requires high-power fundamental lasers, non-linear crystals, and complex optical alignment systems, all of which are expensive. The invention uses a straightforward electromagnetic field excitation system with helium gas, which is much cheaper to manufacture and maintain while achieving the same DUV photon generation goal.
Solution Approach 2:
The patent uses helium gas as the working medium, which is relatively inexpensive and can be easily replenished. The system uses simple electromagnetic field excitation components rather than expensive non-linear optical crystals and high-power laser generators. This approach adopts the principle of using cheap, easily replaceable components to reduce overall manufacturing cost.
3Illumination intensity
If helium atoms undergo spontaneous decay from 1s2p state to ground state, then DUV photons are generated, but the photons have no coherence and cannot form lasers
Solution Approach 1:
The patent merges two excitation mechanisms: electromagnetic field excitation (to populate the 1s2p state) and optical field excitation (to achieve population inversion and stimulate emission). By combining these two excitation methods, the system first uses electromagnetic fields to efficiently populate the excited state, then uses optical fields to stimulate coherent emission, thereby achieving both high photon generation and laser coherence.
Solution Approach 2:
The patent uses helium atoms as an intermediary medium between electromagnetic field excitation and coherent light generation. The helium atoms are first excited by electromagnetic fields to the 1s2p state, then serve as the active medium for optical stimulation to produce coherent DUV laser photons. This intermediary approach allows the system to benefit from both excitation methods while achieving coherent laser output.
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 coherent photons, reducing the size and cost of DUV lasers while achieving shorter wavelengths, improving efficiency and industrial applicability.
Implementation Method 1
through the electromagnetic interaction between an electromagnetic field and the helium atoms, helium atoms in a commonly used helium lamp that generates 21.2 eV DUV photons can be excited from 1s2 ground state to 1s2p (1P1) state
Implementation Method 2
an excitation laser, configured to drive electrons in the intermediate state at different spatial positions in the medium to the ground state through a stimulated emission process to generate coherent photons to form a laser
Data Source
AI summary
The present invention provides a laser, including: a medium, having a ground state, an intermediate state, and an excited state in ascending order of energy; an excitation system, configured to excite electrons in the medium from the ground state to the intermediate state; and an excitation laser, configured to drive electrons in the intermediate state at different spatial positions in the medium to the ground state through a stimulated emission process with a fixed phase relationship, to generate a laser with a shorter relative wavelength. Due to the use of an excitation laser to drive electrons from the intermediate state, the photons generated by the stimulated emission have coherence, thereby forming a laser. In the present invention, an excitation system performing primary pumping combined with an excitation laser with a relatively long wavelength performing secondary pumping generate lasers with a relatively short wavelength, and the structure of the short-wavelength laser is simple, compact, and easy to be implemented. In addition, the cost of the short-wavelength laser can be reduced, and a laser with a shorter wavelength can be obtained.