Diode-Pumped Er:YAG Laser Rod Geometry for High-Energy 2.94 μm Pulses
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Solution Overview
Problem
Diode-pumped solid-state lasers face limitations in achieving high average power and pulse energy due to the rod's ability to withstand pump power, leading to restricted laser performance and unsuitable beam quality for defense applications.
Innovation Solution
A high energy pulsed 2.94 μm diode pumped Er:YAG laser system with a 50% doped Er:YAG laser rod, having concave faces with a radius of curvature between 200 mm to 500 mm, and pumped by multiple laser diode packages to achieve a maximum average power of 220 W and pulse energies of at least 1.5 J, with a full divergent angle of no more than 50 mrad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rod diameter is reduced to concentrate pump power density, then pump power density increases, but the average power is limited by the rod's ability to withstand pump power
Solution Approach 1:
The patent changes the geometric parameters of the laser rod, specifically using a larger diameter rod (4-5 mm) compared to conventional small rods (<2.39 mm), and optimizes the doping concentration (50% Er:YAG) to achieve high average power output without exceeding the rod's withstand capability
2Power
If the rod cross-section area is reduced to increase pump power density, then pump power density increases, but the average power output is limited
Solution Approach 1:
The patent optimizes multiple parameters including rod diameter (4-5 mm), rod length (126-188 mm), doping concentration (50%), and pump power density (≤30 W/mm³) to simultaneously achieve high pump power density and high average power output of at least 220 W
3Productivity
If the pump power inside the laser active medium is increased to improve laser performance, then laser performance improves, but the rod breaks due to excessive pump power
Solution Approach 1:
The patent maintains pump power density within the safe limit of ≤30 W/mm³ while achieving high laser performance through optimized rod dimensions (4-5 mm diameter, 126-188 mm length) and 50% doping concentration, preventing rod breakage
Solution Approach 2:
The patent specifies concave faces with radius of curvature between 200-500 mm to optimize the optical cavity and distribute stress, improving both laser performance and rod durability
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 system produces reliable high-energy pulses with improved beam quality and efficiency, meeting the requirements of defense applications with enhanced pulse energy and frequency, surpassing current market standards.
Implementation Method 1
the laser pump source is configured to pump energy into the laser rod to thereby cause the laser to produce a laser beam that has wavelength of 2.94 μm
Implementation Method 2
at least one laser pump source configured to pump energy into the laser rod to thereby cause the laser to produce a laser beam
Data Source
AI summary
Years of experimentation, testing, and refinement have resulted in designs for lasers that can produce laser beams that have a 2.94 μm wavelength and a previously unachievable output power of at least 220 W. Specific designs for such high power 2.94 μm lasers are presented herein such that those practiced in the art may achieve similar results without undue experimentation. Such a laser can include a laser rod and at least one laser pump source. The laser pump source is configured to pump energy into the laser rod to thereby cause the laser to produce a laser beam that has a wavelength of 2.94 μm. The laser beam has a maximum average power of at least 220 W. The laser beam includes a plurality of pulses that each have an energy of at least 1.5 J at 0.5 ms at 150 Hz.