飛秒激光寫入制備的激光晶體和陶瓷通道光波導(dǎo)
發(fā)布時(shí)間：2018-07-25 21:20
【摘要】：集成電路可以在高度集成化空間內(nèi)實(shí)現(xiàn)對電信號的傳輸和信息處理,但目前發(fā)展遇到諸如體積問題、功耗問題等瓶頸。與之相比,集成光路具備在微小區(qū)域?qū)庑盘枌?shí)現(xiàn)高穩(wěn)定性和低功耗高速傳輸和高速處理的能力,在未來光通信、光信息處理等領(lǐng)域有著廣闊的應(yīng)用前景。自從二十世紀(jì)六十年代末集成光學(xué)概念被提出后,人們開始了對集成光路的研究。與傳統(tǒng)光學(xué)器件的大體積、低穩(wěn)定性、光束準(zhǔn)直困難不同,集成光路是主要依賴于光子器件和光波導(dǎo)器件,實(shí)現(xiàn)集成化、微小型化的集成光子學(xué)系統(tǒng),其性能穩(wěn)定可靠、效率高、制造成本低廉。光波導(dǎo)器件能夠限制和引導(dǎo)光的傳輸,是集成光子學(xué)系統(tǒng)中連接不同功能光子器件所必不可少的基礎(chǔ)元件,如同“木桶原理”中最短的木板一樣,光波導(dǎo)器件質(zhì)量的好壞將直接決定了整體集成光子學(xué)系統(tǒng)質(zhì)量的優(yōu)劣。光波導(dǎo)是由折射率較低的區(qū)域包圍的折射率較高的區(qū)域形成的結(jié)構(gòu),通過全反射的方式可以將光的傳輸控制在微米甚至納米量級尺寸的微小區(qū)域,并且較大程度增強(qiáng)波導(dǎo)腔內(nèi)光密度,使得諸如非線性光學(xué)特性和激光特性等光學(xué)性質(zhì)得到加強(qiáng)。耦合器、光開關(guān)、波導(dǎo)激光器、波導(dǎo)頻率轉(zhuǎn)換器等已經(jīng)在無源或有源光波導(dǎo)器件中得到實(shí)現(xiàn)。根據(jù)結(jié)構(gòu)特征,光波導(dǎo)可分為平面光波導(dǎo)與通道型光波導(dǎo)兩種。與僅能在一維尺度對光傳輸進(jìn)行限制的平面光波導(dǎo)相比,通道型光波導(dǎo)(如脊型光波導(dǎo)、條形光波導(dǎo)等)可以對光在二維甚至三維空間尺度上的傳輸進(jìn)行限制和引導(dǎo),擁有更高的研究價(jià)值和更廣闊的應(yīng)用前景。作為常見的光波導(dǎo)基質(zhì)材料,介電晶體與透明陶瓷材料具有優(yōu)良的物理化學(xué)特性和光學(xué)特性,在眾多領(lǐng)域應(yīng)用廣泛。其中激光晶體和激光陶瓷是最為常見全固體激光器工作物質(zhì),它們增益高,導(dǎo)熱性好,具有比玻璃材料更低的激光閾值。具有高集成度、高效率和低損耗的光波導(dǎo)器件與激光材料相結(jié)合,可以實(shí)現(xiàn)穩(wěn)定地波導(dǎo)激光輸出。隨著集成光子器件的發(fā)展,對器件的集成度和多功能化要求越來越高,小型化、高功率波導(dǎo)激光的實(shí)現(xiàn)為未來與非線性光學(xué)元件相結(jié)合,構(gòu)成多功能集成光子器件打下堅(jiān)實(shí)基礎(chǔ)。迄今為止,人們已經(jīng)利用多種技術(shù)在激光晶體和激光陶瓷中實(shí)現(xiàn)了光波導(dǎo)的制備,比如離子注入技術(shù)、離子交換技術(shù)、聚焦質(zhì)子寫入技術(shù)、飛秒激光寫入技術(shù)等。其中飛秒激光寫入技術(shù)是利用超短脈沖激光,在微時(shí)間尺度實(shí)現(xiàn)對材料的微空間尺度三維加工技術(shù)。飛秒激光單個(gè)脈沖的功率可高達(dá)1015W級別,可以對金屬、透明晶體材料、有機(jī)化合物等諸多物質(zhì)進(jìn)行加工,其三維加工的分辨率更是可達(dá)到10 nm以內(nèi),在軍事、生物醫(yī)學(xué)、科研、加工制造等行業(yè)應(yīng)用廣泛。本論文中利用飛秒寫入技術(shù)加工透明介電晶體與陶瓷制備光波導(dǎo)的原理是利用加工過程中,脈沖激光可聚焦于材料表面或內(nèi)部,飛秒激光脈沖能量通過掃描過程中所引起的多光子吸收、雪崩電離或者隧穿電離等非線性光學(xué)效應(yīng)被材料吸收,并在聚焦位置附近區(qū)域引起折射率變化。最終通過設(shè)置合理的加工參數(shù)(如寫入速度、寫入能量等),多次的掃描加工便可快速地制備出光波導(dǎo)結(jié)構(gòu)。由于飛秒寫入技術(shù)效率高、成本低、無污染、可調(diào)控性強(qiáng),且適用于大部分的激光晶體與陶瓷材料的加工,因而具有其他加工技術(shù)所不能比擬的優(yōu)勢。本論文的主要內(nèi)容包括利用飛秒激光寫入技術(shù)實(shí)現(xiàn)激光晶體和陶瓷材料中通道光波導(dǎo)的制備；利用微熒光光譜與微拉曼光譜測試技術(shù),分析光波導(dǎo)的形成機(jī)理；以及通過實(shí)驗(yàn)對波導(dǎo)導(dǎo)波特性和激光特性的研究等。根據(jù)實(shí)驗(yàn)選用激光晶體／陶瓷材料和所制備光波導(dǎo)器件類型的不同,可以將本論文的主要工作歸納為如下內(nèi)容：采用飛秒激光寫入技術(shù),在摻釹釔鋁石榴石(Nd：YAG)陶瓷中制備橫截面積相當(dāng)?shù)牧呅�、圓形和梯形包層光波導(dǎo)。通過共聚焦熒光測試表明飛秒激光寫入過程引起晶格畸變,寫入痕跡處折射率明顯降低,所組成包層結(jié)構(gòu)所包裹的區(qū)域即為波導(dǎo)區(qū)域,并且Nd3+離子的熒光特性在波導(dǎo)區(qū)得到較好的保存。實(shí)驗(yàn)證明包層波導(dǎo)導(dǎo)波特性出色,圓形包層波導(dǎo)的傳輸損耗可低至0.8 dB/cm同時(shí)波導(dǎo)在TE和TM偏振方向下激光特性均表現(xiàn)優(yōu)異,其中圓形包層結(jié)構(gòu)波導(dǎo)激光最高輸出功率達(dá)181 mW,斜效率為44%,激光閾值僅為121 mW。在Nd:YAG晶體中制備雙包層波導(dǎo)結(jié)構(gòu),該結(jié)構(gòu)與包層光纖結(jié)構(gòu)類似,可用于制備“光纖-波導(dǎo)-光纖”集成器件。激光泵浦實(shí)驗(yàn)表明,內(nèi)包層結(jié)構(gòu)中實(shí)現(xiàn)單模波導(dǎo)激光輸出,TE偏振方向下波導(dǎo)激光最高輸出功率達(dá)384 mW,斜效率為46.1%,激光閾值僅為106 mW。在Nd:YAG晶體中制備“包層+雙線型”波導(dǎo)結(jié)構(gòu),通過微熒光測試表明外包層結(jié)構(gòu)的制備使得雙線型波導(dǎo)內(nèi)部殘余應(yīng)力場呈現(xiàn)各向同性,且通過激光泵浦實(shí)驗(yàn)在TE與TM偏振方向下在雙線型波導(dǎo)結(jié)構(gòu)內(nèi)均實(shí)現(xiàn)高效率波導(dǎo)激光輸出,波導(dǎo)激光最高輸出功率分別為53 mW和0.15 W,斜效率分別為6.6%和15.1%。該工作為首次報(bào)道在Nd:YAG晶體雙線型光波導(dǎo)中TM與TE偏振方向下均實(shí)現(xiàn)激光輸出。利用飛秒激光寫入技術(shù)在釹摻雜釓鎵石榴石(Nd:GGG)晶體中制備不同尺寸的圓形包層光波導(dǎo),實(shí)驗(yàn)表明所制備包層波導(dǎo)結(jié)構(gòu)導(dǎo)波特性優(yōu)良�；诙嗣骜詈舷到y(tǒng)進(jìn)行激光特性測試,實(shí)驗(yàn)表明隨著波導(dǎo)尺寸的增加,波導(dǎo)激光特性明顯增強(qiáng),波導(dǎo)激光最高輸出功率209 mW,斜效率為44.4%。利用飛秒激光寫入技術(shù)首次在釹摻雜鎢酸釓鉀晶體(Nd:KGW)晶體中制備雙線型光波導(dǎo)。實(shí)驗(yàn)中我們重構(gòu)雙線型光波導(dǎo)折射率變化,并根據(jù)重構(gòu)模型模擬波導(dǎo)導(dǎo)波模式,結(jié)果表明所制備雙線型光波導(dǎo)具有良好的導(dǎo)波特性。通過微熒光測試表明Nd3+離子熒光特性在波導(dǎo)區(qū)得到較好保存。通過激光泵浦實(shí)驗(yàn)我們在寬度為15和20 μm的雙線型波導(dǎo)中實(shí)現(xiàn)最高輸出功率分別為22.5和33 mW,斜效率分別為52.3%和41.4%的連續(xù)波導(dǎo)激光輸出。利用飛秒激光寫入技術(shù)在釹摻雜釩酸釓(Nd:GdVO4)晶體中制備單包層及雙包層光波導(dǎo)�；诙嗣骜詈舷到y(tǒng),我們在直徑為150 μm的包層光波導(dǎo)中實(shí)現(xiàn)1064.5 nm波長的連續(xù)波導(dǎo)激光輸出,斜效率高達(dá)68%,最高輸出功率為0.57 W。利用石墨烯作為可飽和吸收體,我們實(shí)現(xiàn)調(diào)Q波導(dǎo)激光,脈沖頻率最高為17.8MHz,脈沖寬度為75 ns,脈沖能量為19 nJ。通過微拉曼光譜測試雙包層波導(dǎo)結(jié)構(gòu)詳細(xì)研究了飛秒寫入過程中引起的晶格畸變等情況。TE與TM偏振方向下在內(nèi)包層波導(dǎo)結(jié)構(gòu)中均實(shí)現(xiàn)單模波導(dǎo)激光輸出,得益于較高模場重合度和有效吸收橫截面積,其最高輸出功率達(dá)到0.43 W,對應(yīng)波導(dǎo)激光斜效率為52.3%,與同尺寸單包層波導(dǎo)激光特性相比,表現(xiàn)更為優(yōu)異。利用飛秒激光寫入技術(shù),在釹摻雜釔鋁石榴石(Nd:YAG)晶體中制備分支角度不同的Y分支型光波導(dǎo)器件。測試表明,Y分支波導(dǎo)結(jié)構(gòu)具有優(yōu)良的導(dǎo)波特性,632.8 nm波長下傳輸損耗約為1.1 dB/cm。激光泵浦試驗(yàn)表明,隨著分支角度減小,Y分支波導(dǎo)器件的激光特性明顯增強(qiáng),實(shí)現(xiàn)最高輸出功率為201 mW,斜效率為20.2%的1064 nm波長波導(dǎo)激光輸出。利用石墨烯作為可飽和吸收體,將其置于波導(dǎo)出射端面和波導(dǎo)上表面,利用其偏振吸收特性實(shí)現(xiàn)調(diào)Q波導(dǎo)激光的輸出。使用雙層石墨烯置于波導(dǎo)出射端面時(shí),脈沖激光在不同偏振方向表現(xiàn)基本相同,最高脈沖頻率為3.0MHz,脈沖寬度為90 ns,脈沖能量達(dá)到63 nJ；使用多層石墨烯覆蓋于波導(dǎo)上表面時(shí),脈沖激光在不同偏振方向下的特性被詳細(xì)研究：p偏振方向下,石墨烯吸收效果明顯,調(diào)Q激光最高脈沖頻率為2.0 MHz,最大脈沖能量為40 nJ,s偏振方向下石墨烯吸收效果降低,調(diào)Q激光最高脈沖頻率為2.3MHz,脈沖能量增加至50 nJ。
[Abstract]:Integrated circuits can achieve transmission and information processing of electrical signals in highly integrated space. However, the development of integrated circuits has bottlenecks such as volume problems and power consumption problems. Since the concept of integrated optics was put forward in the late 1960s, people began to study the integrated optical path, which is different from the large volume, low stability, and beam collimation difficulties of the traditional optical devices. The integrated optical path is mainly dependent on the photonic devices and optical waveguide devices to achieve integration. The integrated and miniaturized integrated photonics system has stable and reliable performance, high efficiency and low manufacturing cost. The optical waveguide device can restrict and guide the transmission of light. It is essential for the integrated photonics system to connect different functional photonic devices. Like the shortest wooden board in the "wood bucket principle", the quality of the optical waveguide device. The quality of the integrated photonics system will directly determine the quality of the integrated photonics system. The optical waveguide is a structure with high refractive index area surrounded by a region of low refractive index, and the transmission of light can be controlled in micro or nanometer size regions by full reflection, and the waveguide cavity is enhanced to a greater degree. Density, the optical properties, such as nonlinear optical properties and laser characteristics, are strengthened. Couplers, optical switches, waveguide lasers, waveguide frequency converters, etc. have been realized in passive or active optical waveguides. According to the structural features, the optical waveguides can be divided into two types of planar and channel optical waveguides. Compared with planar optical waveguides with limited optical transmission, channel type optical waveguides (such as ridge type optical waveguides, strip light conductance, etc.) can restrict and guide the transmission of light on two-dimensional and even three-dimensional space scales, and have higher research value and wider application prospects. Bright ceramic materials have excellent physical and chemical properties and optical properties, and are widely used in many fields. Laser crystals and laser ceramics are the most common solid state laser working substances. They have high gain, good thermal conductivity, and lower laser threshold than glass materials. With the combination of laser materials and laser materials, a stable waveguide laser output can be achieved. With the development of integrated photonic devices, the requirements for the integration and multifunction of the devices are becoming more and more high, miniaturized, and the realization of the high power waveguide laser is a solid foundation for the integration of the nonlinear optical components and the multi-function integrated photonic devices. So far, people have made use of various techniques to fabricate optical waveguides in laser crystals and laser ceramics, such as ion implantation, ion exchange, focusing proton writing, femtosecond laser writing, etc. in which femtosecond laser writing technique uses ultrashort pulse laser to realize micro space on material in micro time scale. The power of femtosecond laser single pulse can be as high as 1015W level, which can be processed for many materials such as metal, transparent crystal material, organic compound and so on. The resolution of 3D processing can be less than 10 nm, and it is widely used in military, biomedical, scientific research, manufacturing and other industries. The principle of writing technology to fabricate transparent dielectric crystals and ceramic optical waveguides is that in the process of processing, the pulse laser can focus on the surface or inside of the material. The femtosecond laser pulse energy is absorbed by the multi photon absorption caused by the scanning process, the avalanche ionization or tunneling ionization and other non linear optical effects are absorbed by the material, and in the focusing position. By setting reasonable processing parameters (such as writing speed, writing energy, etc.), the optical waveguide structure can be quickly prepared by setting reasonable processing parameters, such as high efficiency, low cost, no pollution, strong regulation, and suitable for the addition of most laser crystals and ceramic materials. The main contents of this paper include the fabrication of channel optical waveguides in laser crystals and ceramic materials by using femtosecond laser writing technology. The formation mechanism of optical waveguides is analyzed by micro fluorescence spectroscopy and micro Raman spectroscopy, and the waveguide conductance is analyzed through experiments. According to the selection of laser crystal / ceramic material and the type of optical waveguide device, the main work of this paper can be summed up as follows: using femtosecond laser writing technique to prepare hexagonal hexagonal area in neodymium yttrium aluminum garnet (Nd:YAG) ceramics. The confocal fluorescence test shows that the lattice distortion is caused by the writing process of the femtosecond laser and the refractive index of the writing trace is obviously reduced. The region wrapped in the cladding structure is the waveguide region, and the fluorescence characteristics of the Nd3+ ions are well preserved in the waveguide region. The experimental results show that the guided wave characteristic of the cladding waveguide is proved. The transmission loss of circular cladding waveguide can be as low as 0.8 dB/cm and the waveguides have excellent performance in both TE and TM polarization. The maximum output power of the circular cladding waveguide laser is 181 mW, the oblique efficiency is 44%, the laser threshold is only 121 mW. in the preparation of the double clad waveguide structure in the Nd:YAG crystal, and the structure and cladding fiber The structure is similar and can be used to prepare the "fiber waveguide fiber" integrated device. The laser pumping experiment shows that the highest output power of the waveguide laser in the TE polarization direction is 384 mW, the oblique efficiency is 46.1%, the laser threshold is only 106 mW., and the "cladding + double line" waveguide structure is prepared in the Nd:YAG crystal. The micro fluorescence test shows that the internal residual stress field in the dual line waveguide is isotropic, and the high efficiency waveguide laser output is realized in the dual line waveguide structure under the polarization direction of TE and TM by the laser pumping experiment. The maximum output power of the waveguide laser is 53 mW and 0.15 W respectively. The oblique efficiency is respectively. For the first time, 6.6% and 15.1%. are reported to achieve laser output in the polarization direction of both TM and TE in Nd:YAG crystal dual line waveguides. Using femtosecond laser writing technique to prepare different sizes of circular cladding waveguides in neodymium doped gadolinium garnet (Nd:GGG) crystals, the experimental results show that the guided wave characteristics of the prepared cladding waveguide are excellent. The laser characteristics of the coupling system are tested. The experiment shows that with the increase of the waveguide size, the characteristics of the waveguide laser are obviously enhanced, the maximum output power of the waveguide laser is 209 mW, the oblique efficiency is 44.4%., and the double line optical waveguide is first prepared by the femtosecond laser writing technique in the Nd doped gadolinium tungstate crystal (Nd:KGW) crystal for the first time. The refractive index change of the double linear waveguide is changed and the guided wave mode is simulated by the reconstructed model. The results show that the double line light wave guide has good guided wave characteristics. The fluorescence characteristics of the Nd3+ ion are well preserved in the waveguide region by the micro fluorescence test. The double wire type wave with the width of 15 and 20 um m is tested by laser pumping. In the guide, the maximum output power is 22.5 and 33 mW and the oblique efficiency is 52.3% and 41.4% respectively. The single cladding and double cladding optical waveguides are prepared by femtosecond laser writing technique in Nd doped gadolinium (Nd:GdVO4) crystal. Based on the end face coupling system, we realize 1064 in the cladding waveguide with a diameter of 150 micron m. The continuous waveguide laser output at.5 nm wavelength is up to 68% and the maximum output power is 0.57 W. using graphene as a saturable absorber. We realize the modulated Q waveguide laser, the highest pulse frequency is 17.8MHz, the pulse width is 75 ns, the pulse energy is 19 nJ., and the two cladding waveguide structures are measured in detail by the micro Raman spectrum. The single mode waveguide laser output is realized in the inner cladding waveguide structure under the polarization direction of.TE and TM. The maximum output power of the waveguide laser is 0.43 W, and the oblique efficiency of the corresponding waveguide laser is 52.3%, compared with the characteristic of the same size single cladding waveguide laser. By using femtosecond laser writing technique, Y branching optical waveguide devices with different branch angles are prepared in Nd doped yttrium aluminum garnet (Nd:YAG) crystals. The test shows that the Y branch waveguide structure has excellent guided wave characteristics. The transmission loss at 632.8 nm wavelength is about 1.1 dB/cm. laser pumping test, and the branch angle decreases with the branch angle reduction. The laser characteristic of the Y branch waveguide device is obviously enhanced. The output power of the 1064 nm wavelength waveguide laser with the maximum output power of 20.2% and the oblique efficiency of 20.2% is 1064 nm. Using graphene as a saturable absorber, it is placed on the end surface of the waveguide and the upper surface of the waveguide, and the output of the modulated Q waveguide laser is realized by its polarization absorption characteristics. When graphene is placed at the end surface of the waveguide, the pulse laser is basically the same in the direction of different polarization, the highest pulse frequency is 3.0MHz, the pulse width is 90 ns and the pulse energy reaches 63 nJ. When the multilayer graphite is covered on the upper surface of the waveguide, the characteristics of the pulse laser down at different polarization sides are studied in detail: Graphite polarization direction, graphite. The absorption effect of allene is obvious, the highest pulse frequency of Q laser is 2 MHz, the maximum pulse energy is 40 nJ, the absorption effect of graphene is reduced in the direction of S polarization, the maximum pulse frequency of Q laser is 2.3MHz, and the pulse energy is increased to 50 nJ.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN25
，
本文編號：2145117
[Abstract]:Integrated circuits can achieve transmission and information processing of electrical signals in highly integrated space. However, the development of integrated circuits has bottlenecks such as volume problems and power consumption problems. Since the concept of integrated optics was put forward in the late 1960s, people began to study the integrated optical path, which is different from the large volume, low stability, and beam collimation difficulties of the traditional optical devices. The integrated optical path is mainly dependent on the photonic devices and optical waveguide devices to achieve integration. The integrated and miniaturized integrated photonics system has stable and reliable performance, high efficiency and low manufacturing cost. The optical waveguide device can restrict and guide the transmission of light. It is essential for the integrated photonics system to connect different functional photonic devices. Like the shortest wooden board in the "wood bucket principle", the quality of the optical waveguide device. The quality of the integrated photonics system will directly determine the quality of the integrated photonics system. The optical waveguide is a structure with high refractive index area surrounded by a region of low refractive index, and the transmission of light can be controlled in micro or nanometer size regions by full reflection, and the waveguide cavity is enhanced to a greater degree. Density, the optical properties, such as nonlinear optical properties and laser characteristics, are strengthened. Couplers, optical switches, waveguide lasers, waveguide frequency converters, etc. have been realized in passive or active optical waveguides. According to the structural features, the optical waveguides can be divided into two types of planar and channel optical waveguides. Compared with planar optical waveguides with limited optical transmission, channel type optical waveguides (such as ridge type optical waveguides, strip light conductance, etc.) can restrict and guide the transmission of light on two-dimensional and even three-dimensional space scales, and have higher research value and wider application prospects. Bright ceramic materials have excellent physical and chemical properties and optical properties, and are widely used in many fields. Laser crystals and laser ceramics are the most common solid state laser working substances. They have high gain, good thermal conductivity, and lower laser threshold than glass materials. With the combination of laser materials and laser materials, a stable waveguide laser output can be achieved. With the development of integrated photonic devices, the requirements for the integration and multifunction of the devices are becoming more and more high, miniaturized, and the realization of the high power waveguide laser is a solid foundation for the integration of the nonlinear optical components and the multi-function integrated photonic devices. So far, people have made use of various techniques to fabricate optical waveguides in laser crystals and laser ceramics, such as ion implantation, ion exchange, focusing proton writing, femtosecond laser writing, etc. in which femtosecond laser writing technique uses ultrashort pulse laser to realize micro space on material in micro time scale. The power of femtosecond laser single pulse can be as high as 1015W level, which can be processed for many materials such as metal, transparent crystal material, organic compound and so on. The resolution of 3D processing can be less than 10 nm, and it is widely used in military, biomedical, scientific research, manufacturing and other industries. The principle of writing technology to fabricate transparent dielectric crystals and ceramic optical waveguides is that in the process of processing, the pulse laser can focus on the surface or inside of the material. The femtosecond laser pulse energy is absorbed by the multi photon absorption caused by the scanning process, the avalanche ionization or tunneling ionization and other non linear optical effects are absorbed by the material, and in the focusing position. By setting reasonable processing parameters (such as writing speed, writing energy, etc.), the optical waveguide structure can be quickly prepared by setting reasonable processing parameters, such as high efficiency, low cost, no pollution, strong regulation, and suitable for the addition of most laser crystals and ceramic materials. The main contents of this paper include the fabrication of channel optical waveguides in laser crystals and ceramic materials by using femtosecond laser writing technology. The formation mechanism of optical waveguides is analyzed by micro fluorescence spectroscopy and micro Raman spectroscopy, and the waveguide conductance is analyzed through experiments. According to the selection of laser crystal / ceramic material and the type of optical waveguide device, the main work of this paper can be summed up as follows: using femtosecond laser writing technique to prepare hexagonal hexagonal area in neodymium yttrium aluminum garnet (Nd:YAG) ceramics. The confocal fluorescence test shows that the lattice distortion is caused by the writing process of the femtosecond laser and the refractive index of the writing trace is obviously reduced. The region wrapped in the cladding structure is the waveguide region, and the fluorescence characteristics of the Nd3+ ions are well preserved in the waveguide region. The experimental results show that the guided wave characteristic of the cladding waveguide is proved. The transmission loss of circular cladding waveguide can be as low as 0.8 dB/cm and the waveguides have excellent performance in both TE and TM polarization. The maximum output power of the circular cladding waveguide laser is 181 mW, the oblique efficiency is 44%, the laser threshold is only 121 mW. in the preparation of the double clad waveguide structure in the Nd:YAG crystal, and the structure and cladding fiber The structure is similar and can be used to prepare the "fiber waveguide fiber" integrated device. The laser pumping experiment shows that the highest output power of the waveguide laser in the TE polarization direction is 384 mW, the oblique efficiency is 46.1%, the laser threshold is only 106 mW., and the "cladding + double line" waveguide structure is prepared in the Nd:YAG crystal. The micro fluorescence test shows that the internal residual stress field in the dual line waveguide is isotropic, and the high efficiency waveguide laser output is realized in the dual line waveguide structure under the polarization direction of TE and TM by the laser pumping experiment. The maximum output power of the waveguide laser is 53 mW and 0.15 W respectively. The oblique efficiency is respectively. For the first time, 6.6% and 15.1%. are reported to achieve laser output in the polarization direction of both TM and TE in Nd:YAG crystal dual line waveguides. Using femtosecond laser writing technique to prepare different sizes of circular cladding waveguides in neodymium doped gadolinium garnet (Nd:GGG) crystals, the experimental results show that the guided wave characteristics of the prepared cladding waveguide are excellent. The laser characteristics of the coupling system are tested. The experiment shows that with the increase of the waveguide size, the characteristics of the waveguide laser are obviously enhanced, the maximum output power of the waveguide laser is 209 mW, the oblique efficiency is 44.4%., and the double line optical waveguide is first prepared by the femtosecond laser writing technique in the Nd doped gadolinium tungstate crystal (Nd:KGW) crystal for the first time. The refractive index change of the double linear waveguide is changed and the guided wave mode is simulated by the reconstructed model. The results show that the double line light wave guide has good guided wave characteristics. The fluorescence characteristics of the Nd3+ ion are well preserved in the waveguide region by the micro fluorescence test. The double wire type wave with the width of 15 and 20 um m is tested by laser pumping. In the guide, the maximum output power is 22.5 and 33 mW and the oblique efficiency is 52.3% and 41.4% respectively. The single cladding and double cladding optical waveguides are prepared by femtosecond laser writing technique in Nd doped gadolinium (Nd:GdVO4) crystal. Based on the end face coupling system, we realize 1064 in the cladding waveguide with a diameter of 150 micron m. The continuous waveguide laser output at.5 nm wavelength is up to 68% and the maximum output power is 0.57 W. using graphene as a saturable absorber. We realize the modulated Q waveguide laser, the highest pulse frequency is 17.8MHz, the pulse width is 75 ns, the pulse energy is 19 nJ., and the two cladding waveguide structures are measured in detail by the micro Raman spectrum. The single mode waveguide laser output is realized in the inner cladding waveguide structure under the polarization direction of.TE and TM. The maximum output power of the waveguide laser is 0.43 W, and the oblique efficiency of the corresponding waveguide laser is 52.3%, compared with the characteristic of the same size single cladding waveguide laser. By using femtosecond laser writing technique, Y branching optical waveguide devices with different branch angles are prepared in Nd doped yttrium aluminum garnet (Nd:YAG) crystals. The test shows that the Y branch waveguide structure has excellent guided wave characteristics. The transmission loss at 632.8 nm wavelength is about 1.1 dB/cm. laser pumping test, and the branch angle decreases with the branch angle reduction. The laser characteristic of the Y branch waveguide device is obviously enhanced. The output power of the 1064 nm wavelength waveguide laser with the maximum output power of 20.2% and the oblique efficiency of 20.2% is 1064 nm. Using graphene as a saturable absorber, it is placed on the end surface of the waveguide and the upper surface of the waveguide, and the output of the modulated Q waveguide laser is realized by its polarization absorption characteristics. When graphene is placed at the end surface of the waveguide, the pulse laser is basically the same in the direction of different polarization, the highest pulse frequency is 3.0MHz, the pulse width is 90 ns and the pulse energy reaches 63 nJ. When the multilayer graphite is covered on the upper surface of the waveguide, the characteristics of the pulse laser down at different polarization sides are studied in detail: Graphite polarization direction, graphite. The absorption effect of allene is obvious, the highest pulse frequency of Q laser is 2 MHz, the maximum pulse energy is 40 nJ, the absorption effect of graphene is reduced in the direction of S polarization, the maximum pulse frequency of Q laser is 2.3MHz, and the pulse energy is increased to 50 nJ.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN25
，
本文編號：2145117
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