飞秒激光写入制备的激光晶体和陶瓷通道光波导
发布时间：2018-07-25 21:20
【摘要】：集成电路可以在高度集成化空间内实现对电信号的传输和信息处理,但目前发展遇到诸如体积问题、功耗问题等瓶颈。与之相比,集成光路具备在微小区域对光信号实现高稳定性和低功耗高速传输和高速处理的能力,在未来光通信、光信息处理等领域有着广阔的应用前景。自从二十世纪六十年代末集成光学概念被提出后,人们开始了对集成光路的研究。与传统光学器件的大体积、低稳定性、光束准直困难不同,集成光路是主要依赖于光子器件和光波导器件,实现集成化、微小型化的集成光子学系统,其性能稳定可靠、效率高、制造成本低廉。光波导器件能够限制和引导光的传输,是集成光子学系统中连接不同功能光子器件所必不可少的基础元件,如同“木桶原理”中最短的木板一样,光波导器件质量的好坏将直接决定了整体集成光子学系统质量的优劣。光波导是由折射率较低的区域包围的折射率较高的区域形成的结构,通过全反射的方式可以将光的传输控制在微米甚至纳米量级尺寸的微小区域,并且较大程度增强波导腔内光密度,使得诸如非线性光学特性和激光特性等光学性质得到加强。耦合器、光开关、波导激光器、波导频率转换器等已经在无源或有源光波导器件中得到实现。根据结构特征,光波导可分为平面光波导与通道型光波导两种。与仅能在一维尺度对光传输进行限制的平面光波导相比,通道型光波导(如脊型光波导、条形光波导等)可以对光在二维甚至三维空间尺度上的传输进行限制和引导,拥有更高的研究价值和更广阔的应用前景。作为常见的光波导基质材料,介电晶体与透明陶瓷材料具有优良的物理化学特性和光学特性,在众多领域应用广泛。其中激光晶体和激光陶瓷是最为常见全固体激光器工作物质,它们增益高,导热性好,具有比玻璃材料更低的激光阈值。具有高集成度、高效率和低损耗的光波导器件与激光材料相结合,可以实现稳定地波导激光输出。随着集成光子器件的发展,对器件的集成度和多功能化要求越来越高,小型化、高功率波导激光的实现为未来与非线性光学元件相结合,构成多功能集成光子器件打下坚实基础。迄今为止,人们已经利用多种技术在激光晶体和激光陶瓷中实现了光波导的制备,比如离子注入技术、离子交换技术、聚焦质子写入技术、飞秒激光写入技术等。其中飞秒激光写入技术是利用超短脉冲激光,在微时间尺度实现对材料的微空间尺度三维加工技术。飞秒激光单个脉冲的功率可高达1015W级别,可以对金属、透明晶体材料、有机化合物等诸多物质进行加工,其三维加工的分辨率更是可达到10 nm以内,在军事、生物医学、科研、加工制造等行业应用广泛。本论文中利用飞秒写入技术加工透明介电晶体与陶瓷制备光波导的原理是利用加工过程中,脉冲激光可聚焦于材料表面或内部,飞秒激光脉冲能量通过扫描过程中所引起的多光子吸收、雪崩电离或者隧穿电离等非线性光学效应被材料吸收,并在聚焦位置附近区域引起折射率变化。最终通过设置合理的加工参数(如写入速度、写入能量等),多次的扫描加工便可快速地制备出光波导结构。由于飞秒写入技术效率高、成本低、无污染、可调控性强,且适用于大部分的激光晶体与陶瓷材料的加工,因而具有其他加工技术所不能比拟的优势。本论文的主要内容包括利用飞秒激光写入技术实现激光晶体和陶瓷材料中通道光波导的制备；利用微荧光光谱与微拉曼光谱测试技术,分析光波导的形成机理；以及通过实验对波导导波特性和激光特性的研究等。根据实验选用激光晶体／陶瓷材料和所制备光波导器件类型的不同,可以将本论文的主要工作归纳为如下内容：采用飞秒激光写入技术,在掺钕钇铝石榴石(Nd：YAG)陶瓷中制备横截面积相当的六边形、圆形和梯形包层光波导。通过共聚焦荧光测试表明飞秒激光写入过程引起晶格畸变,写入痕迹处折射率明显降低,所组成包层结构所包裹的区域即为波导区域,并且Nd3+离子的荧光特性在波导区得到较好的保存。实验证明包层波导导波特性出色,圆形包层波导的传输损耗可低至0.8 dB/cm同时波导在TE和TM偏振方向下激光特性均表现优异,其中圆形包层结构波导激光最高输出功率达181 mW,斜效率为44%,激光阈值仅为121 mW。在Nd:YAG晶体中制备双包层波导结构,该结构与包层光纤结构类似,可用于制备“光纤-波导-光纤”集成器件。激光泵浦实验表明,内包层结构中实现单模波导激光输出,TE偏振方向下波导激光最高输出功率达384 mW,斜效率为46.1%,激光阈值仅为106 mW。在Nd:YAG晶体中制备“包层+双线型”波导结构,通过微荧光测试表明外包层结构的制备使得双线型波导内部残余应力场呈现各向同性,且通过激光泵浦实验在TE与TM偏振方向下在双线型波导结构内均实现高效率波导激光输出,波导激光最高输出功率分别为53 mW和0.15 W,斜效率分别为6.6%和15.1%。该工作为首次报道在Nd:YAG晶体双线型光波导中TM与TE偏振方向下均实现激光输出。利用飞秒激光写入技术在钕掺杂钆镓石榴石(Nd:GGG)晶体中制备不同尺寸的圆形包层光波导,实验表明所制备包层波导结构导波特性优良。基于端面耦合系统进行激光特性测试,实验表明随着波导尺寸的增加,波导激光特性明显增强,波导激光最高输出功率209 mW,斜效率为44.4%。利用飞秒激光写入技术首次在钕掺杂钨酸钆钾晶体(Nd:KGW)晶体中制备双线型光波导。实验中我们重构双线型光波导折射率变化,并根据重构模型模拟波导导波模式,结果表明所制备双线型光波导具有良好的导波特性。通过微荧光测试表明Nd3+离子荧光特性在波导区得到较好保存。通过激光泵浦实验我们在宽度为15和20 μm的双线型波导中实现最高输出功率分别为22.5和33 mW,斜效率分别为52.3%和41.4%的连续波导激光输出。利用飞秒激光写入技术在钕掺杂钒酸钆(Nd:GdVO4)晶体中制备单包层及双包层光波导。基于端面耦合系统,我们在直径为150 μm的包层光波导中实现1064.5 nm波长的连续波导激光输出,斜效率高达68%,最高输出功率为0.57 W。利用石墨烯作为可饱和吸收体,我们实现调Q波导激光,脉冲频率最高为17.8MHz,脉冲宽度为75 ns,脉冲能量为19 nJ。通过微拉曼光谱测试双包层波导结构详细研究了飞秒写入过程中引起的晶格畸变等情况。TE与TM偏振方向下在内包层波导结构中均实现单模波导激光输出,得益于较高模场重合度和有效吸收横截面积,其最高输出功率达到0.43 W,对应波导激光斜效率为52.3%,与同尺寸单包层波导激光特性相比,表现更为优异。利用飞秒激光写入技术,在钕掺杂钇铝石榴石(Nd:YAG)晶体中制备分支角度不同的Y分支型光波导器件。测试表明,Y分支波导结构具有优良的导波特性,632.8 nm波长下传输损耗约为1.1 dB/cm。激光泵浦试验表明,随着分支角度减小,Y分支波导器件的激光特性明显增强,实现最高输出功率为201 mW,斜效率为20.2%的1064 nm波长波导激光输出。利用石墨烯作为可饱和吸收体,将其置于波导出射端面和波导上表面,利用其偏振吸收特性实现调Q波导激光的输出。使用双层石墨烯置于波导出射端面时,脉冲激光在不同偏振方向表现基本相同,最高脉冲频率为3.0MHz,脉冲宽度为90 ns,脉冲能量达到63 nJ；使用多层石墨烯覆盖于波导上表面时,脉冲激光在不同偏振方向下的特性被详细研究：p偏振方向下,石墨烯吸收效果明显,调Q激光最高脉冲频率为2.0 MHz,最大脉冲能量为40 nJ,s偏振方向下石墨烯吸收效果降低,调Q激光最高脉冲频率为2.3MHz,脉冲能量增加至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.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN25
，
本文编号：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.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN25
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本文编号：2145117
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