發(fā)布時(shí)間：2018-11-23 20:21

【摘要】：碟片激光器泵浦光斑的均勻性是減小激光晶體熱畸變、實(shí)現(xiàn)高光束質(zhì)量、高平均功率、高光光轉(zhuǎn)換效率激光輸出的核心單元技術(shù)之一,也是碟片激光器優(yōu)化設(shè)計(jì)難點(diǎn)所在。本文針對(duì)基于共軛雙拋物面鏡的多次泵浦結(jié)構(gòu),通過(guò)對(duì)泵浦源均勻性、拋物面鏡單次聚焦光斑均勻性、多次泵浦空間重疊均勻性的深入分析,在綜合考慮系統(tǒng)失調(diào)對(duì)泵浦均勻性影響的同時(shí),開(kāi)展碟片激光器多次泵浦系統(tǒng)的綜合優(yōu)化設(shè)計(jì),并給出最佳設(shè)計(jì)方案,開(kāi)展相應(yīng)的實(shí)驗(yàn)研究。具體研究?jī)?nèi)容如下：第一,針對(duì)泵浦源的均勻性,通過(guò)對(duì)比分析微透鏡陣列、柱面鏡組、多邊形勻化棒和方光纖四種勻化方案,結(jié)合多次泵浦系統(tǒng)光路結(jié)構(gòu)特點(diǎn),選擇方光纖作為最佳方案。第二,針對(duì)單次聚焦光斑的均勻性,通過(guò)分析拋物面鏡成像特性,指出聚焦光斑邊沿像點(diǎn)彌散斑幾何半徑應(yīng)小于150μm。第三,針對(duì)多次聚焦光斑的中心重合特性,通過(guò)分析拋物面鏡自身光學(xué)特性、雙拋物面鏡失配以及碟片晶體離焦對(duì)各次聚焦光斑相對(duì)位置關(guān)系的影響,證明共軛雙拋物面鏡多次泵浦結(jié)構(gòu)具有極好的多次泵浦穩(wěn)定性,保證多個(gè)聚焦光斑幾何中心的重合。第四,針對(duì)多次聚焦光斑的邊沿重合特性,通過(guò)分析碟片晶體傾角和拋物面鏡成像特性對(duì)聚焦光斑畸變的影響,指出畸變的本質(zhì)原因是準(zhǔn)直光束離軸入射拋物面鏡導(dǎo)致離軸方向及其正交方向的成像垂軸放大率不相等,提出基于共焦點(diǎn)分段拋物面鏡和一維擴(kuò)束系統(tǒng)的兩種光斑畸變校正方法,達(dá)到較好的校正效果。第五,提出一種加入直角棱鏡的共軛雙拋物面鏡多次泵浦方案,通過(guò)合理設(shè)計(jì)實(shí)現(xiàn)系統(tǒng)中各項(xiàng)關(guān)鍵指標(biāo)全局最優(yōu),設(shè)計(jì)出兩套泵浦均勻性分別達(dá)到93.8%和96.31%、泵浦功率密度為4.3kW/cm2和5.48 kW/cm2.泵浦次數(shù)達(dá)20次和48次的多次泵浦系統(tǒng)。第六,對(duì)泵浦均勻性的各研究環(huán)節(jié)進(jìn)行實(shí)驗(yàn)驗(yàn)證,最終在碟片晶體上獲得了非常均勻的疊加泵浦光斑,基于兩套多次泵浦系統(tǒng)進(jìn)行CW碟片激光器運(yùn)行實(shí)驗(yàn),一套系統(tǒng)實(shí)現(xiàn)了M2≈1.3的高光束質(zhì)量激光輸出,輸出功率125W,光光轉(zhuǎn)換效率34.2%,另一套系統(tǒng)實(shí)現(xiàn)了654W的高平均功率激光輸出和47.2%的高光光轉(zhuǎn)換效率,光束質(zhì)量M2≈7.2。
[Abstract]:The uniformity of laser spot pumped by disc laser is one of the core unit techniques to reduce the thermal distortion of laser crystal, achieve high beam quality, high average power and high optical conversion efficiency. It is also a difficult point in the optimization design of disc laser. In this paper, based on the conjugate double parabolic mirror, the uniformity of pump source, the uniformity of single focus spot of parabolic mirror and the overlap uniformity of multiple pumping space are analyzed. While considering the effect of system misalignment on pumping uniformity, the optimal design of disc laser multiple pumping system is carried out, and the optimal design scheme is given, and the corresponding experimental research is carried out. The main contents are as follows: first, aiming at the uniformity of pump source, four homogenization schemes, such as microlens array, cylindrical mirror group, polygonal homogenized rod and square fiber, are compared and analyzed. Choose square fiber as the best scheme. Secondly, in view of the uniformity of single focus spot, by analyzing the imaging characteristics of parabolic mirror, it is pointed out that the geometric radius of the focal spot edge diffusing spot should be less than 150 渭 m. Thirdly, according to the central coincidence characteristics of multi-focus spot, the effects of parabolic mirror's own optical properties, double parabolic mirror mismatch and disk crystal defocus on the relative position of each focusing spot are analyzed. It is proved that the multi-pump structure of conjugate double-parabolic mirror has excellent stability of multiple pumping, which ensures the coincidence of the geometric centers of the focusing spot. Fourthly, in view of the edge coincidence characteristics of multi-focus spot, the effects of crystal inclination and parabolic mirror imaging characteristics on focusing spot distortion are analyzed. It is pointed out that the essential reason of distortion is that the axial magnification of the imaging vertical axis in the off-axis direction and its orthogonal direction is not equal due to the off-axis incidence of the collimated beam and the parabolic mirror. Two correction methods of spot distortion based on common focus segmented parabolic mirror and one-dimensional beam expander system are proposed to achieve better correction effect. Fifthly, a multi-pump scheme of conjugate double-parabolic mirror with right-angle prism is proposed. The global optimum of the key indexes in the system is realized by reasonable design, and the pump uniformity of two sets is up to 93.8% and 96.31% respectively. Pump power density of 4.3kW/cm2 and 5.48 kW/cm2. Multiple pumping system with 20 and 48 pumping times. Sixth, the experimental verification of the pump uniformity is carried out. Finally, a very uniform superposition pump spot is obtained on the disk crystal. Based on two sets of multiple pumping systems, the CW disc laser operation experiment is carried out. One system achieves a high beam quality laser output of M2 鈮，

本文編號(hào)：2352590