Solid-State Laser Pumping via Acoustic Beam Scanning
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Solution Overview
Problem
High power density pumping of solid-state laser and nonlinear media leads to thermal issues such as thermally induced mechanical stresses, refractive index gradients, and limited power density due to heat dissipation challenges, which existing methods like cryo-cooling and moving the pumped solid are complex and inefficient.
Innovation Solution
The solution involves rapidly moving the pumped volume through the solid-state medium using a deflection device, such as a scanner, to distribute heat input over a larger volume, reducing temperature gradients and absolute temperatures, and using imaging optics to maintain beam direction and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power density pumping is applied to solid-state laser media, then gain and laser efficiency are improved, but thermal effects such as thermally induced mechanical stresses and refractive index gradients increase
Solution Approach 1:
The patent applies dynamic scanning of the pump beam across the solid-state medium using acoustic radiation pressure to continuously move the pumped volume. This dynamic approach distributes heat input over time and space, reducing thermal accumulation while maintaining high peak power density pumping, thereby resolving the contradiction between high power density and thermal effect mitigation
Solution Approach 2:
The patent employs periodic pulsed pumping combined with periodic scanning motion of the pump beam. By delivering energy in periodic pulses and scanning the pumped location periodically, the system allows thermal diffusion between pulses, reducing average thermal load while maintaining high instantaneous power density for efficient lasing
2Temperature
If cryo-cooling is used to increase thermal conductivity, then temperature gradients are reduced, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical cryo-cooling systems with an acoustic field-based pumping method. By using acoustic radiation pressure to scan the pump beam through the medium, thermal management is achieved through dynamic heat distribution rather than passive thermal conduction enhancement, eliminating the need for complex cryogenic infrastructure
Solution Approach 2:
The patent introduces acoustic waves as an intermediary mechanism to achieve thermal management. The acoustic field serves as a mediator that enables dynamic scanning of the pumped volume, distributing thermal load without requiring direct thermal contact with heat sinks or complex cooling systems
3Temperature
If the pumped solid is moved to distribute heat capacity, then absolute temperature rise is reduced, but mechanical complexity increases
Solution Approach 1:
The patent replaces mechanical movement of the solid-state medium with optical scanning of the pump beam using acoustic radiation pressure. Instead of physically moving the gain medium to distribute heat, the system moves the pump beam through the stationary medium, achieving the same thermal distribution effect with significantly reduced mechanical complexity
Solution Approach 2:
The patent inverts the conventional approach by keeping the medium stationary and moving the pump beam instead. Rather than moving the pumped solid to distribute heat capacity, the system scans the pump radiation through the medium, achieving thermal management through the inverse mechanism with simpler implementation
4Loss of energy
If disk or slab geometry is used to increase heat-dissipating surface, then heat dissipation is improved, but pumped volume increases
Solution Approach 1:
The patent uses dynamic scanning to concentrate high power density pumping in a small instantaneous volume while distributing thermal load over a larger effective volume through time-averaged scanning. This temporal-dynamic approach achieves improved heat dissipation characteristics without increasing the physical pumped volume, maintaining compact geometry
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 effectively reduces thermal gradients and temperatures, allowing for increased power density and scalability in laser or nonlinear media, while maintaining beam quality and simplifying heat dissipation, thus enhancing laser efficiency and medium durability.
Implementation Method 1
The pump beam is scanned acoustically radiative-pressure-induced in the focused beam focal point region of the solid body
Implementation Method 2
Between the reflector and the movable mirror there is an imaging optics, with which a scanning movement of the movable mirror together with the imaging optics is converted into a translation in the solid-state medium
Implementation Method 3
heating by the laser process or absorption and thus temperature gradients are unavoidable
Data Source
Figure 1Aa~1Ad
Figure 1Ba~1Bd
Figure 2Aa~2Ad
AI summary
The invention relates to an arrangement with a fixed solid-state medium, which is pumped via a pumping device by means of pumped radiation, wherein the pumped radiating is radiated into the solid-state medium via a deflection unit. The invention is characterized in that the deflection unit offsets the radiation, comprising the pumped radiation and the laser radiation or radiation in the form of frequency-converted pumped radiation, transversally (transversal to the propagation direction) in a time-dependant manner, while substantially maintaining the propagation direction.