【摘要】：啁啾脈沖放大技術(shù)是產(chǎn)生高能脈沖激光的重要手段,脈沖壓縮光柵是啁啾脈沖放大系統(tǒng)的核心器件。針對更短脈沖的放大需求,本論文研究金屬-介質(zhì)膜光柵和后鍍膜光柵。金屬-介質(zhì)膜光柵指浮雕光柵結(jié)構(gòu)刻蝕在金屬-介質(zhì)膜系表面形成的光柵,后鍍膜光柵指在浮雕光柵表面鍍金屬層和介質(zhì)膜層形成的光柵。金屬-介質(zhì)膜光柵的研制過程中,我們首先分析上海光機所提供的光柵設(shè)計槽形對應(yīng)的工藝容差范圍,在此基礎(chǔ)上開始光柵制作工藝實驗。首先,制作光刻膠掩模,并用氧氣等離子體灰化手段對其槽深與占寬比進行修正;通過實驗確定了金屬-介質(zhì)膜光柵占寬比與掩模占寬比的關(guān)系,掩模占寬比控制范圍為0.14至0.18,刻蝕后可得到占寬比為0.15至0.21的金屬-介質(zhì)膜光柵。然后,我們通過實驗確定了金屬-介質(zhì)膜光柵槽形在離子束刻蝕過程中的演化規(guī)律,建立對掩模槽深、占寬比變化不敏感的刻蝕監(jiān)測模型,實現(xiàn)對金屬-介質(zhì)膜光柵刻蝕槽深的實時在線監(jiān)測。根據(jù)實驗結(jié)果,這一監(jiān)測方法對槽深的控制范圍為310nm至320nm,精度為10nm。我們制作完成的金屬-介質(zhì)膜光柵中衍射效率超過90%的最大帶寬為169nm(705-874nm),帶寬內(nèi)平均效率93.71%,峰值是95.1%,位于810nm波長處。后鍍膜光柵研制的探索性更強,我們通過實驗確定了合適的基底材料與刻蝕工藝,并制作出了不同槽形參數(shù)的裸光柵基底。之后,實驗對比了不同鍍膜工藝的成膜質(zhì)量,確定了合適的鍍膜方案,即利用電子束蒸發(fā)工藝鍍金膜,用離子束濺射鍍膜工藝鍍多層介質(zhì)膜。我們制作完成的裸光柵槽深分布范圍為170nm至370nm,占寬比范圍是0.40-0.71。根據(jù)掃描電鏡圖片,分析這些裸光柵鍍膜后的槽形演變規(guī)律,建立唯象的槽形演變模型�；诮⒌墓鈻挪坌窝葑兡Ｐ�,對后鍍膜光柵參數(shù)進行優(yōu)化設(shè)計,并對其工藝容差作理論分析。優(yōu)化設(shè)計后的后鍍膜光柵效率大于90%的帶寬為100nm(755nm-855nm),峰值效率為95.70%(785nm波長處),755nm-845nm波長區(qū)間的平均效率為93.21%。優(yōu)化設(shè)計與容差分析結(jié)果表明,在現(xiàn)有工藝條件下,優(yōu)化得到的后鍍膜光柵能夠滿足脈沖壓縮光柵的效率指標(biāo)要求,并具有較好的可加工性。
[Abstract]:Chirped pulse amplification is an important means to produce high energy pulse laser. Pulse compression grating is the core device of chirped pulse amplification system. In this paper, metal-dielectric film grating and post-coating grating are studied in order to amplify the shorter pulse. The metal-dielectric film grating refers to the gratings etched on the surface of the metal-dielectric film system by the structure of the relief grating, and the post-coated grating refers to the grating formed by the plating of metal layer and the dielectric film layer on the surface of the relief grating. In the development of metal-dielectric film gratings, we first analyze the corresponding technological tolerance range of grating design grooves provided by Shanghai Optical Machine, and on this basis begin the fabrication experiments of gratings. Firstly, the photolithographic mask is made and the depth and duty cycle of the cell are modified by oxygen plasma ashing. The relationship between the duty cycle ratio of the metal-dielectric film grating and the width ratio of the mask is determined by experiments. The control range of the mask duty ratio is from 0.14 to 0.18. After etching, the metal-dielectric film grating with the duty ratio of 0.15 to 0.21 can be obtained. Then, we determine the evolution rule of metal-dielectric film grating grooves in the process of ion beam etching through experiments, and establish a etching monitoring model which is not sensitive to the change of mask groove depth and width ratio. The real-time on-line monitoring of the etched groove depth of metal-dielectric film grating is realized. According to the experimental results, the control range of the groove depth is from 310nm to 320nm, and the precision is 10nm. The maximum bandwidth of diffraction efficiency over 90% in the fabricated metal-dielectric film grating is 169nm (705-874nm). The average bandwidth efficiency is 93.71 and the peak value is 95.1, which is located at the wavelength of 810nm. The experimental results show that the substrate material and etching process are suitable and the bare grating substrate with different grooves has been fabricated. After that, the film quality of different coating processes was compared, and the suitable coating scheme was determined, that is, using electron beam evaporation process to deposit gold film and ion beam sputtering process to deposit multilayer dielectric film. The groove depth distribution ranges from 170nm to 370 nm, and the ratio of width to width is 0.40-0.71. Based on scanning electron microscope (SEM) images, the evolution law of the grooves after these bare gratings were analyzed, and the phenomenological grooves evolution model was established. Based on the evolution model of grating grooves, the parameters of post-coating gratings are optimized and their technological tolerances are analyzed theoretically. After optimized design, 100nm (755nm-855nm), 95.70% peak efficiency (785nm wavelength) and 93.21% average efficiency of 755nm-845nm wavelength range can be obtained when the efficiency of post-coating grating is more than 90%. The results of optimum design and tolerance analysis show that the optimized post-coated grating can meet the efficiency requirements of pulse compression grating under the existing technological conditions and has good processability.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TN25

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