本文關(guān)鍵詞：深紫外與真空紫外飛秒激光的產(chǎn)生及應(yīng)用探索　出處：《華東師范大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 深紫外 真空紫外 飛秒激光 三次諧波 等離子體光柵 相位匹配 激光誘導(dǎo)熒光光譜學(xué) 激光消融 光學(xué)倍頻

【摘要】：紫外超短脈沖激光具有較強(qiáng)的單光子能量,在非線性光學(xué)物理中能夠產(chǎn)生非線性展寬、頻率上轉(zhuǎn)換、高密度等離子、頻率合成、化學(xué)分解等豐富的物理機(jī)制。利用紫外激光的獨(dú)特優(yōu)勢,脈沖寬度為飛秒量級的紫外光源應(yīng)用在高次諧波、等離子體透明器件、綠色化學(xué)處理、氣體痕量檢測、激光誘導(dǎo)擊穿光譜分析等領(lǐng)域具有廣闊的前景。紫外光源還具備多光子電離系數(shù)低、成絲等離子體密度高、空間分辨率好等優(yōu)勢,受限于高能量飛秒脈沖的產(chǎn)生及有效控制,此方向上的原理與技術(shù)研究仍是國際上研究的熱點(diǎn)。本文研究了高能量深紫外與真空紫外飛秒激光的產(chǎn)生與應(yīng)用,激光輸出中心波長分別為266 nm、200 nm和89nm,能量分別達(dá)2.2 mJ、0.1 mJ和190 nJ,同時深入探索了不同波長激光脈沖的成絲過程以及其中的物理機(jī)制,概括起來可分為以下幾個方面：1)運(yùn)用KBBF直接倍頻輸出深紫外激光特性,提出倍頻-補(bǔ)償-診斷的全固態(tài)深紫外激光系統(tǒng),基于中心波長為800 nm的鈦寶石激光系統(tǒng)經(jīng)過三倍頻后獲得266 nm三次諧波,并將輸出的400nm激光通過KBBF晶體,利用其直接倍頻特點(diǎn)產(chǎn)生高能量的200 nm脈沖輸出,并引入棱鏡對壓縮脈沖,最后運(yùn)用四波混頻原理將266 nm脈沖對200 nm脈沖寬度進(jìn)行檢測。實驗首次將0.1 mJ的200 nm深紫外脈沖壓縮至飛秒量級,并運(yùn)用頻率分辨光學(xué)快門技術(shù)對深紫外脈沖進(jìn)行診斷。2)基于紫外與深紫外激光在惰性氣體介質(zhì)中的非線性混頻原理,提出真空紫外波段多色場產(chǎn)生方案,實驗中使用重復(fù)頻率10 Hz的800 nm的鈦寶石激光系統(tǒng),配合級聯(lián)BBO晶體組產(chǎn)生的266nm脈沖與直接倍頻產(chǎn)生的400 nm脈沖在氬氣中開展四波混頻,在真空中收集到波長分別為200 nm、133 nm、114 nm、100 nm及89 nm真空紫外多色激光,實驗首次將紫外光用于進(jìn)一步產(chǎn)生真空紫外激光的混頻過程,并通過調(diào)整氣壓控制入射脈沖的相位匹配,驗證了三階非線性過程中的相位鎖定現(xiàn)象。3)基于氣體介質(zhì)中三次諧波的產(chǎn)生原理,提出壓力梯度與光絲截斷雙重增強(qiáng)方案,將上述產(chǎn)生的高能量266nm脈沖分束后聚焦于氬氣樣品池中分別成絲,將其中一束光焦點(diǎn)處引入真空環(huán)境形成氣壓梯度,在后向收集中心波長為89nm的極紫外激光光譜,并通過另一根深紫外光絲的截斷產(chǎn)生了超過5000倍的增強(qiáng)。該實驗方案實現(xiàn)兩點(diǎn)突破：一方面,在266nm激光脈沖的三次諧波產(chǎn)生過程中,壓力梯度環(huán)境避免了古依相移現(xiàn)象的產(chǎn)生,改善了相位匹配條件；另一方面,266nm光絲在焦點(diǎn)處對另一路形成干擾,以交叉增強(qiáng)等離子體密度的方式及時將89 nm極紫外光向外圍轉(zhuǎn)移,避免了光絲能量回流。雙重增強(qiáng)方案為今后更短波長的真空紫外光源產(chǎn)生奠定了原理和技術(shù)基礎(chǔ)。4)基于等離子體光柵中高功率密度與電子密度特定,創(chuàng)新性地提出了雙色場紫外等離子體光柵激光消融技術(shù),以兩束400nm紫外激光在空氣中成絲并交叉相干形成紫外等離子體光柵,另一束中心波長800nm的紅外光絲以布拉格角入射形成增強(qiáng)紫外等離子體光柵。成絲與相干作用產(chǎn)生的等離子體熱電子在紅外脈沖的加速下碰撞更多的原子產(chǎn)生更強(qiáng)的自由電子密度,因此在激光消融的實驗探索中,雙色場等離子體方案相對等能量的單根光絲方案在樣品靶的消融時間上提升了近6倍。該實驗結(jié)果具有四點(diǎn)突破：(1)相對長脈沖激光消融技術(shù)引入了飛秒光絲的消融方案；(2)驗證了飛秒紫外激光產(chǎn)生增強(qiáng)等離子體光柵在激光消融技術(shù)中的優(yōu)勢；(3)實驗觀察到高能量的粒子激發(fā)熒光信號；(4)發(fā)現(xiàn)激光消融過程中氣體介質(zhì)對結(jié)果具有顯著影響。最后,深紫外與真空紫外飛秒激光的產(chǎn)生還將在液體動力學(xué)分析,化學(xué)反應(yīng),更深紫外強(qiáng)脈沖形成方面開展更多的實踐,有望在光學(xué)精密微加工、阿秒脈沖產(chǎn)生、高能態(tài)分子激發(fā)、超快精密光譜檢測等領(lǐng)域產(chǎn)生更多的應(yīng)用。
[Abstract]:UV ultrashort pulse laser with single photon energy is strong, can produce nonlinear broadening in nonlinear optical physics, frequency conversion, high density plasma, frequency synthesis, chemical decomposition and other rich physical mechanism. The use of the unique advantages of the UV laser, the pulse width of the femtosecond ultraviolet light source used in the harmonic, transparent plasma green chemical processing device, trace gas detection, laser induced breakdown spectroscopy analysis field has broad prospects. The UV light also has a low coefficient of multiphoton ionization, filamentation plasma density, spatial resolution and other advantages, is limited to generate high energy femtosecond pulse and effective control, the direction of the principle and technology research is the international research focus. This paper studies the production and application of high energy deep ultraviolet and vacuum ultraviolet femtosecond laser, the laser output wavelength division For 266 nm, 200 nm and 89nm respectively, energy up to 2.2 mJ, 0.1 mJ and 190 nJ, and further explore the spinning process of different wavelengths of laser pulse and the physical mechanism, it can be divided into the following aspects: 1) by direct frequency doubling of KBBF deep ultraviolet laser output characteristics of all solid state deep ultraviolet laser frequency compensation system is proposed based on the diagnosis, the center wavelength of the Ti: sapphire laser system is 800 nm after three times after obtaining 266 nm three harmonics, and the output of the 400nm laser using KBBF crystal, 200 nm pulse output energy using the direct frequency doubling characteristics, and the introduction of prism compression the pulse, finally using four wave mixing principle of 266 nm pulse of 200 nm pulse width detection. The experiment for the first time 0.1 mJ 200 nm deep ultraviolet femtosecond pulse compression to, and use of deep ultraviolet pulse frequency resolved optical gating technique The diagnosis of.2) nonlinear mixing principle of ultraviolet and deep ultraviolet laser in an inert gas medium based on the vacuum ultraviolet polychromatic field generation scheme, titanium sapphire laser system with 10 Hz repetition frequency in the experiment of 800 nm, with a cascade of BBO crystal group 266nm pulse generation and direct frequency doubling of nm pulse 400 to carry out the four wave mixing in argon, at a wavelength of 200 nm, 133 nm, 114 nm in vacuum collection, 100 nm and 89 nm vacuum ultraviolet multicolor laser, UV light for mixing experiments for the first time will further produce a vacuum ultraviolet laser, and by adjusting the air pressure to control the phase of the incident pulse, and verified in the process of three order nonlinear phase locking phenomenon.3) three harmonic generation principle in gas medium is proposed based on pressure gradient and light silk double truncated enhancement scheme, high energy pulse generated by the 266nm red beam after poly Coke in argon sample pool were silk, a beam of light at the focal point which will be introduced into the vacuum pressure gradient is formed in the environment, to collect center wavelength of 89nm ultraviolet laser spectroscopy, and has produced more than 5000 fold enhancement by truncating the other one deep UV silk. The experimental scheme has two breakthroughs: in three, harmonic 266nm laser pulse generation process, the pressure gradient environment to avoid the Gouy phase shift phenomenon, improve the phase matching condition; on the other hand, the 266nm light wire to form interference on another road to cross at the focus, enhance the plasma density in a timely manner will be 89 nm extreme ultraviolet light to the periphery to avoid the light energy transfer, wire return. Double enhancement program has laid a foundation for the principle and technology of.4 vacuum ultraviolet light source in shorter wavelength) produce plasma grating with high power density and electron density characteristics based on And put forward the innovation of two-color UV plasma grating laser ablation technique, with two 400nm UV laser in air spinning and cross coherent UV plasma grating, infrared light wire the other beam with center wavelength of 800nm to enhance the formation of Prague incident UV plasma grating. The free electron density of the plasma thermal electrons and coherent effects of filamentation in accelerating the infrared pulse collision more atoms produced stronger, therefore in the exploration of laser ablation experiments, two color scheme is relatively single energy plasma filament scheme is increased by nearly 6 times in the sample target ablation time. The experimental results have four breakthroughs: (1 for relatively long pulse laser ablation) ablation technology is introduced into the filament; (2) to verify the femtosecond ultraviolet laser produced plasma enhanced grating in laser ablation technology in the Advantage; (3) observed high energy particle fluorescence signal; (4) it is found that the laser ablation process of gas medium has a significant impact on the results. Finally, the deep ultraviolet and vacuum ultraviolet femtosecond laser generation is also analyzed, the chemical reaction in the liquid dynamics, more intense ultraviolet pulse forming more practice carry out, is expected in the optical precision micro machining, attosecond pulse generation, high-energy excited state molecules, resulting in more applications of ultrafast precision spectroscopy detection.

【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：O437

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