Centrosymmetrical Laser Discs for Dopant Gradient Compensation
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Solution Overview
Problem
The existing methods for producing monocrystalline optical elements with optically active centers are limited by concentration gradients of impurities, which restrict the size and homogeneity of the usable area, particularly in laser systems, due to uneven dopant distribution during crystallization.
Innovation Solution
A pair of active optical elements with mutually mirror and/or rotationally symmetrical geometric shapes and concentration gradients are used, where the elements are arranged to achieve a maximum concentration difference of ±5% across the optical beam's cross-section, ensuring optical homogeneity and increasing the usable area by rotating and geometrically connecting them to form a composite material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crystallization methods (Czochralski, Kyropoulos, Bridgman, etc.) are used to produce monocrystalline optical elements, then optically active centers are formed, but concentration gradients of dopants occur that limit the usable area and homogeneity
Solution Approach 1:
The patent divides the monocrystal into multiple sections along the growth axis, selecting regions with suitable dopant concentration ranges (within ±5% of target concentration). These sections are then processed into separate optical elements, effectively segmenting the crystal to eliminate the harmful effects of concentration gradients while utilizing the maximum possible material volume.
Solution Approach 2:
The patent applies different quality criteria to different regions of the crystal. By identifying and selecting specific zones where dopant concentration falls within the acceptable range (±5% deviation), the method ensures that each optical element is produced from material with locally optimal properties, thereby achieving high optical homogeneity in the final product.
2Quantity of substance
If the concentration of dopants is changed during crystal growth, then optically active centres are formed, but the dopant distribution becomes uneven with gradients exceeding acceptable limits
Solution Approach 1:
The patent performs preliminary analysis of the dopant concentration distribution in the grown crystal before processing. By measuring and mapping the concentration gradients in advance, the method identifies suitable regions for optical element production, ensuring that dopant distribution uniformity requirements are met before the actual optical component manufacturing begins.
Solution Approach 2:
The patent changes the selection criteria based on the measured dopant concentration profile. By adjusting which regions of the crystal are selected for processing, depending on their local dopant concentration values, the method ensures that all produced optical elements meet the required uniformity specifications while maximizing material 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 significantly increases the usable area of optical elements, enhancing the performance of optical amplifiers and laser systems by eliminating inhomogeneities and achieving a substantial increase in the achievable capacity of laser slabs.
Implementation Method 1
the elements are arranged to achieve a maximum concentration difference of ±5% across the optical beam's cross-section, ensuring optical homogeneity and increasing the usable area by rotating and geometrically connecting them
Data Source
Figure 1~2
Figure 3~5
AI summary
This invention relates to the preparation of solid-state optical active media (especially monocrystalline) with added optically active centres (dopants) and their use in performance optical amplifiers, lasers in particular. It utilizes a concentration gradient of optically active dopants previously perceived as a negative side effect of the preparation of laser monocrystalline materials; it reaches the optically homogeneous performance of the active media on passing optical laser beam by an appropriate geometrical arrangement of the elements of at least one pair of mutually centrosymmetrical or rotationally symmetrical active optical elements. From a grown solid-state laser gain medium having a crystal growth axis (2) and a dopant concentration gradient (4) along the growth axis (2) the top and bottom parts are removed allowing inspection of the medium along the two ends (1). The medium is for example Nd:YAG. Laser discs (D1,D2) are cut along a direction (3) parallel to the growth axis (2) and the two laser discs are joined together with opposite dopant concentration gradients (4) thereby providing a laser disc with reduced dopant concentration inhomogeneities seen by an optical beam (5). A larger part of a laser boule can be used for production of laser discs or slabs having integrated equal laser dopant concentration.