本文選題：氣體等離子體 + 飛秒激光��； 參考：《華中科技大學(xué)》2015年碩士論文

【摘要】：將飛秒激光聚焦在空氣中形成氣體等離子體,氣體等離子體可以輻射出高強(qiáng)度、寬帶寬的太赫茲波,是一種很有應(yīng)用前景的太赫茲源,受到了人們的廣泛關(guān)注。通常采用的激光是中心波長(zhǎng)為800nm的飛秒激光以及它的倍頻脈沖。本論文基于光電流模型,對(duì)氣體等離子體輻射太赫茲波輻射的特性進(jìn)行了理論研究,主要工作如下:(1)在一維情況下,使用光電流模型對(duì)太赫茲波輻射的基本特性進(jìn)行了研究,分析了激光強(qiáng)度、基倍頻脈沖相對(duì)相位差、電離飽和等因素對(duì)太赫茲波輻射的影響進(jìn)行了研究。(2)研究了不同激光波長(zhǎng)產(chǎn)生太赫茲波的區(qū)別,發(fā)現(xiàn)在一定波長(zhǎng)范圍內(nèi),太赫茲波強(qiáng)度隨著使用激光波長(zhǎng)的增大而增強(qiáng)。提出了使用800nm的飛秒激光以及其二分之一次諧波用于產(chǎn)生太赫茲波的方案,闡釋了該方案的可行性以及實(shí)際意義。(3)結(jié)合實(shí)際中氣體等離子體產(chǎn)生太赫茲波的方案,在二維情況下,對(duì)太赫茲波輻射的特性進(jìn)行了研究,尤其是解釋了橢圓偏振太赫茲波的產(chǎn)生原因。從理論上說明了太赫茲波橢圓偏振的原因并不完全是等離子體中各種效應(yīng),還與倍頻晶體對(duì)激光偏振的影響有關(guān)。(4)研究了等離子體細(xì)絲的產(chǎn)生,結(jié)合等離子體的特性,分析了等離子體對(duì)激光脈沖傳輸?shù)挠绊?包括光譜的展寬、色散帶來的基倍頻場(chǎng)相對(duì)相位差改變、交叉相位調(diào)制帶來的偏振態(tài)的變化,在此基礎(chǔ)上利用光電流模型推導(dǎo)出等離子體細(xì)絲對(duì)太赫茲波輻射的影響。
[Abstract]:The femtosecond laser is focused in the air to form a gas plasma. The gas plasma can radiate high intensity and broadband terahertz wave. It is a very promising terahertz source, which is widely concerned. The laser is a femtosecond laser with a central wavelength of 800nm and its frequency doubling pulse. This paper is based on this paper. The characteristics of the radiation of the terahertz wave radiation from gas plasma radiation are studied theoretically. The main work is as follows: (1) in one dimension, the basic characteristics of the terahertz wave radiation are studied by using the photocurrent model, and the factors such as the laser intensity, the relative phase difference of the basic frequency doubling pulse and the ionization saturation are analyzed. The effect of radiation is studied. (2) the difference of the terahertz wave generated by different laser wavelengths is studied. It is found that the intensity of the terahertz wave is enhanced with the increase of laser wavelength in a certain wavelength range. A scheme for using 800nm's femtosecond laser and its second harmonic generation to produce terahertz waves is proposed. The feasibility and practical significance. (3) combining the scheme of the terahertz wave produced by the gas plasma in the actual situation, the characteristics of the terahertz wave radiation are studied in the two-dimensional case, especially the cause of the elliptically polarized terahertz wave. It is theoretically explained that the reason for the ellipse polarization of the terahertz wave is not completely the plasma in the plasma. Various effects are also related to the effect of frequency doubling crystals on the polarization of laser. (4) the production of plasma filaments is studied and the effects of plasma on the laser pulse transmission are analyzed, including the broadening of the spectrum, the relative phase difference of the basic frequency doubling field caused by the dispersion and the change of the polarization state caused by the cross phase modulation. On this basis, the influence of plasma filament on terahertz radiation is deduced by using the photocurrent model.

【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O441.4

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本文編號(hào)：1860637