本文選題：飛秒激光 + 色散��； 參考：《北京理工大學》2016年博士論文

【摘要】：飛秒激光微/納制造是一個包含機械、熱力學、光學、材料等多個學科的前沿交叉領域,在國防、醫(yī)療、信息等方面均有廣泛應用。飛秒激光具有超高的峰值功率,其與材料作用是一個從納米到毫米、從飛秒到微秒的非線性、非平衡多尺度過程,與傳統(tǒng)制造的機理完全不同,因此,研究飛秒激光微/納加工技術,對物理及制造科學本身都有著極其重要的意義。隨著微小型化的進一步發(fā)展,對制造品質的要求不斷提高,因此,飛秒激光微/納制造也面臨著新的挑戰(zhàn),如更高的加工質量,更高的加工效率和更好的加工可控性等。在理論上,飛秒激光與材料相互作用過程中,許多經典理論已不再適用,材料光學及熱力學瞬時(飛秒)局部(納米)特性的變化極其重要,需要引入量子力學,以提高其預測精度。在實驗上,飛秒激光微/納加工是一個多參數過程,涉及波長、波形、脈寬、頻率等,但是激光波形和脈寬會在激光傳輸過程中因色散的引入而導致畸變或展寬,影響加工的精度及可重復性;此外,飛秒激光加工的表面質量、加工效率、可控性等仍需要進一步提高。因此,針對上述科學問題,本課題組基于電子動態(tài)調控的思想,提出利用飛秒激光時域整形的方法,解決脈沖的畸變及展寬,通過調控光子與電子的相互作用,控制材料局部瞬時光學和熱力學特性,選擇性激發(fā)材料相變,實現高質量、高效率、更高可控性的飛秒激光微/納制造新方法。本論文主要研究了基于電子動態(tài)調控的時域整形飛秒激光加工非金屬材料(電介質、聚合物和半導體),其主要內容包括:1)以高斯光束為例,建立了飛秒激光在介質中傳輸的色散模型,理論模擬并分析了二階色散、三階色散對飛秒激光脈沖的脈寬及脈沖時域形狀的影響。2)建立了時域整形的飛秒激光與電介質材料相互作用的量子等離子體模型,深入的研究了自由電子的激發(fā)電離、加熱以及材料瞬時局部光學特性的變化。3)搭建了時域整形的飛秒激光微/納加工光路系統(tǒng),系統(tǒng)的研究了時域整形飛秒激光參數對燒蝕彈坑的尺寸(直徑、深度)及表面質量(重鑄、微裂紋)的影響規(guī)律。4)理論推導了基于雙光子聚合加工的特征尺寸與激光輻照參數的關系,利用時域整形的飛秒激光進行聚合加工,實現了λ/12的極限分辨尺寸。5)提出了利用時域整形的飛秒激光高效率制備微流體通道的新方法,并研究了各參數對微通道加工效率的影響規(guī)律。6)研究了時域整形的飛秒激光直寫加工半導體硅的各向異性現象,提出了通過調控飛秒激光的掃描速度、掃描方向和偏振方向,進而調控半導體材料表面周期結構的方向及幾何形貌。本論文所取得的主要創(chuàng)新成果總結如下:1)提出利用時域整形的飛秒激光加工電介質,通過調控電子激發(fā)、電離、復合及相變過程,實現高精度、高質量的微/納加工新方法。首先,通過改變脈沖序列的子脈沖間隔,發(fā)現100 fs-200 fs之間燒蝕增強的新現象。其次,通過改變脈沖序列的子脈沖個數,調控燒蝕結構直徑和深度。最后,通過改變脈沖序列的能量分配比,實現對相變的選擇性激發(fā),從而減少重鑄,提高了材料的表面加工質量。2)提出利用時域整形的飛秒激光在電介質上加工微流體通道,通過調控自由電子密度分布,實現高效率的微/納加工新方法。首先,提出利用液體輔助飛秒激光脈沖序列的方法在電介質材料上加工微通道結構,在相同條件下,加工效率提高了56倍,單次掃描加工微通道的極限深徑比提高了3倍。其次,提出了利用飛秒激光脈沖序列輻照改性化學刻蝕的方法加工微通道結構,在相同的條件下,輻照區(qū)域的刻蝕效率提高了10倍;提出了通過勻減速的掃描方法,改善微通道的截面形狀,實現了優(yōu)化加工。最后,提出利用飛秒激光脈沖序列的方法消除激光偏振對輻照改性區(qū)域的影響,實現各向同性的微通道化學刻蝕加工。3)首次發(fā)現時域整形的線偏振飛秒激光在硅材料表面直寫加工的各向異性新現象,通過調控材料表面等離子體的形成及分布,實現可控性表面微/納加工新方法。在固定點加工中,通過改變脈沖序列子脈沖間隔,調控表面結構的周期及形貌;在激光直寫中,首次發(fā)現并提出了線偏振的飛秒激光在硅材料表面直寫加工的各向異性現象,提出通過改變飛秒激光的偏振、掃描方向、掃描速度等參數,調控表面結構的幾何形貌及方向。
[Abstract]:Femtosecond laser micro / nano manufacturing is a frontier area which includes mechanical, thermodynamic, optical, material and other disciplines. It is widely used in defense, medical, information and so on. Femtosecond laser has ultra high peak power, and its function is a nonlinear, nonequilibrium multiscale process from nanometer to millisecond, from femtosecond to microsecond. It is quite different from the traditional manufacturing mechanism. Therefore, the study of femtosecond laser micro / nanofabrication technology is of great importance to the physics and manufacturing science itself. With the further development of microminiaturization, the requirements for the manufacturing quality are increasing. Therefore, the femtosecond laser micro / nano manufacturing is also facing new challenges, such as higher processing quality. In theory, in the process of interaction between femtosecond laser and material, many classical theories are no longer applicable, and the change of optical and thermodynamic instantaneous (femtosecond) local (nanometer) characteristics is very important. Quantum mechanics is needed to improve its prediction accuracy. In experiment, femtosecond laser Micro / nano machining is a multi parameter process involving wavelengths, waveforms, pulse width and frequency, but the laser wave and pulse width will distort or widen in the process of laser transmission due to the introduction of dispersion, and affect the accuracy and repeatability of the processing. In addition, the surface quality, processing efficiency and controllability of the femtosecond laser processing need to be further improved. Therefore, in view of the above scientific problems, the research group, based on the idea of electronic dynamic regulation, proposes to use the method of femtosecond laser time domain shaping to solve the distortion and broadening of the pulse. By controlling the interaction between the photon and the electron, the local instantaneous optical and thermodynamic properties of the material are controlled, the phase transition of the material is selectively excited and the high quality and high efficiency are realized. A new method of femtosecond laser micro / nano fabrication with higher controllability. This paper mainly studies the time-domain shaping femtosecond laser processing nonmetallic materials (dielectric, polymer and semiconductor) based on electronic dynamic regulation and control. The main contents include: 1) the dispersion model of femtosecond laser propagation in the medium is established with Gauss beam as an example. The theoretical model is established. The effects of the two order dispersion, the three order dispersion on the pulse width and the pulse time domain shape of the femtosecond laser pulse are analyzed and analyzed. The quantum plasma model of the interaction of the femtosecond laser with the dielectric material in the time domain is established. The excited ionization of the free electrons, the heat addition and the change of the instantaneous local optical properties of the material are studied in depth. The two order dispersion and the influence of the three order dispersion on the pulse time domain shape of the femtosecond laser pulse are established. A femtosecond laser micro / nanofabrication optical path system in time domain shaping is built. The effect of time domain shaping femtosecond laser parameters on the size (diameter, depth) and surface quality (recasting, micro crack) of the ablation crater is systematically studied. The relationship between the characteristic size of the two-photon polymerization and the laser irradiation parameters based on the two-photon polymerization is derived, and the use of the.4 is derived. The domain shaping femtosecond laser is polymerized and the limit resolution size.5 of lambda /12 is realized. A new method of high efficiency preparation of microfluidic channel using femtosecond laser in time domain shaping is proposed, and the effect of each parameter on the processing efficiency of microchannel.6) is studied. The orientation and geometry of the periodic structure of the semiconductor material are regulated by regulating the scanning speed, the direction and the direction of polarization of the femtosecond laser. The main achievements in this paper are summarized as follows: 1) the processing of the dielectric by using the femtosecond laser in time domain is proposed, and the electronic excitation and electricity are regulated by the control of electronic excitation. A new method of high precision and high quality micro / nano machining. First, a new phenomenon of ablation enhancement between 100 FS-200 FS is discovered by changing the interval of the pulse sequence. Secondly, the diameter and depth of the ablation structure are regulated by changing the number of subpulses in the pulse sequence. Finally, the energy of the pulse sequence is changed. A new method of micro / nanofabrication is realized by using time domain shaping femtosecond laser to process the microfluidic channel on the dielectric. By adjusting the density distribution of free electrons, a new efficient micro / nanofabrication method is realized by using the time domain shaping femtosecond laser in the dielectric. First, the liquid assisted femtosecond excitation is proposed. The method of optical pulse sequence is used to process microchannel structure on dielectric material. Under the same condition, the machining efficiency is increased by 56 times. The limit depth diameter ratio of the single scanning micro channel is 3 times higher. Secondly, the microchannel structure is processed by using the femtosecond laser pulse sequence to irradiate the modified chemical etching. The etching efficiency of the region is increased by 10 times, and the shape of the microchannel cross section is improved by the uniform deceleration method. Finally, the effect of the laser polarization on the irradiated region is eliminated by the method of the femtosecond laser pulse sequence, and the isotropic microchannel chemical etching process.3 is first discovered. A new anisotropic new phenomenon of linear polarization femtosecond laser processing on the surface of silicon material. By regulating the formation and distribution of the surface plasma of the material, a new method of controllable surface micro / nanofabrication is realized. In the fixed point processing, the periodic and morphology of the surface structure are regulated by changing the pulse interval of the pulse sequence, and the laser is straight. In writing, the isotropic phenomenon of linear polarization of femtosecond laser on the surface of silicon material is discovered and proposed for the first time. The geometric morphology and direction of the surface structure are regulated by changing the polarization, scanning direction and scanning speed of the femtosecond laser.
【學位授予單位】：北京理工大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG665

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本文編號：2079697