【正文】 果。盡我所知，除文中特別加以標(biāo)注和致謝的地方外，不包含其他人或組織已經(jīng)發(fā)表或公布過的研究成果，也不包含我為獲得 及其它教育機(jī)構(gòu)的學(xué)位或?qū)W歷而使用過的材料。 作 者 簽 名： 日 期： 指導(dǎo)教師簽名： 日 期： 使用授權(quán)說明 本人完全了解 大學(xué)關(guān) 于收集、保存、使用畢業(yè)設(shè)計(jì)（論文）的規(guī)定，即：按照學(xué)校要求提交畢業(yè)設(shè)計(jì)（論文）的印刷本和電子版本；學(xué)校有權(quán)保存畢業(yè)設(shè)計(jì)（論文）的印刷本和電子版，并提供目錄檢索與閱覽服務(wù)；學(xué)校可以采用影印、縮印、數(shù)字化或其它復(fù)制手段保存論文；在不以贏利為目的前提下，學(xué)校可以公布論文的部分或全部?jī)?nèi)容。電光調(diào)制器可以對(duì)光波進(jìn)行調(diào)幅、調(diào)強(qiáng)、調(diào)頻、調(diào)相和調(diào)偏振，應(yīng)用領(lǐng) 域非常廣闊。這一理論的優(yōu)點(diǎn)是給出了嚴(yán)格解，應(yīng)用條件沒有特殊限制，其外加電場(chǎng)方向、入射光方向及偏振方向都可以是任意的。通過設(shè)定倒格矢參數(shù)，從而彌補(bǔ)晶體雙折射時(shí) o光和 e光折射率不同造成的相位失配，得到較高的電光效率。模擬結(jié)果表明，“準(zhǔn)相位匹配”概念在電光耦合中起重要作用，另外準(zhǔn)相位匹配條件對(duì)溫度和波長(zhǎng)非常敏感，但允許入射光有較大的失配角。 關(guān)鍵詞：鈮酸鋰，電光效應(yīng)，耦合波，轉(zhuǎn)換效率 長(zhǎng)沙學(xué)院 畢業(yè)設(shè)計(jì) (論文 ) II ABSTRACT Electrooptic modulation， based on linear electrooptic effect， is one of widely used modulation technologies． Electrooptic modulator has been widely used for the modulation of the signals of light， including the modulation of amplitude， intensity, frequency phase and polarization. Our works presented in the thesis are based on the wave coupling theory of linear electrooptic effect, a new electromagic theory put forward by She et. al., whose advantage is with rigorous solution for a light wave with arbitrary polarization propagating along any direction under an arbitrary external electric field. The quasiphasematched (QPM) theory was applied to the electrooptic effect. We derived a general wave coupling equations of QPM linear electrooptic effect， and used resultant equations to investigate the electrooptic effect in periodically poled LiNb03 (PPLN)． By setting the parameters of PPLN grating, we pensated for the phase mismatched which is caused by different index of refraction of the oray and eray when birefringence happens. As a result, high conversion efficiency was obtained. By use of Matlab, the influence of temperature, wavelength, electric field intensity and duty cycle of PPLN on the conversion efficiency of the electrooptical effect were investigated numerically. The results indicate that the QPM condition plays an important role in electrooptic coupling； in addition， the coupling is very sensitive to the temperature and incident light wavelength， but has a large tolerance to the incident direction of light. Our research results will be useful for designing the electrooptic modulator. Keywords: LiNbO3, electrooptic effect, coupled wave, conversion efficiency 長(zhǎng)沙學(xué)院 畢業(yè)設(shè)計(jì) (論文 ) III 目 錄 摘 要 ................................................................................................................ I ABSTRACT...................................................................................................... II 第 1 章 緒論 .................................................................................................... 1 電光效應(yīng)的基本概念 ................................................................................................. 1 線性電光效應(yīng)的應(yīng)用 ................................................................................................. 2 電光效應(yīng)研究的理論發(fā)展 ......................................................................................... 2 本論文的主要工作及其意義 ..................................................................................... 3 第 2 章 LiNbO3的晶體結(jié)構(gòu)和性質(zhì) ................................................................. 5 LiNbO3晶體結(jié)構(gòu) .......................................................................................................... 5 LiNbO3晶體基本性質(zhì) .................................................................................................. 6 LiNbO3晶體特點(diǎn) .......................................................................................................... 6 周期性極化 LiNbO3晶體（ PPLN）的制備 ................................................................. 7 PPLN 晶體的應(yīng)用 ........................................................................................................ 8 LiNbO3晶體折射率方程 .............................................................................................. 9 第 3 章 線性電光效應(yīng)的耦合波理論 ............................................................11 第 4 章 LiNbO3 晶體電光效應(yīng)理論 ............................................................... 17 LiNbO3晶體電光效應(yīng)的折射率橢球分析法 ............................................................ 17 LiNbO3晶體電光效應(yīng)線性耦合波理論分析法 ........................................................ 19 第 5 章 PPLN 結(jié)構(gòu)參數(shù)設(shè)定 ......................................................................... 22 相關(guān)參數(shù)說明 ........................................................................................................... 22 PPLN 結(jié)構(gòu)參數(shù) .......................................................................................................... 22 有效電光系數(shù)設(shè)定 ................................................................................................... 23 第 6 章 數(shù)值模擬與討論 .............................................................................. 25 長(zhǎng)沙學(xué)院 畢業(yè)設(shè)計(jì) (論文 ) IV 溫度 T 的改變對(duì)轉(zhuǎn)換效率η的影響 ....................................................................... 25 波長(zhǎng)λ的改變對(duì)轉(zhuǎn)換效率η的影響 ....................................................................... 28 外電場(chǎng) E的改變對(duì)轉(zhuǎn)換效率η的影響 ................................................................... 30 晶體占空比 D的改變對(duì)轉(zhuǎn)換效率η的影響 ........................................................... 30 結(jié) 論 ............................................................................................................. 32 參考文獻(xiàn) ......................................................................................................... 33 附 錄 ............................................................................................................. 34 致 謝 ............................................................................................................. 41 長(zhǎng)沙學(xué)院 畢業(yè)設(shè)計(jì) (論文 ) 1 第 1 章 緒論 電光效應(yīng)的基本概念 光在各向異 性介質(zhì)中傳播時(shí) 將產(chǎn)生雙折射現(xiàn)象，這種現(xiàn)象是由于晶體結(jié)構(gòu)自身的