基于回音壁模式微球腔的PDH稳频技术

光学微球腔因其回音壁模式可获得极高的品质因数而受到广泛关注.本文分析了Fabry-Perot腔和微球腔的基本原理,通过CO2激光熔融光纤实验制得了直径为1.2 mm的微球腔,并测试了微球腔和锥形光纤耦合结构的耦合特性.采用典型的PDH稳频系统设计了基于微球腔的稳频系统,分析了用于鉴频的误差曲线的吸收特性和色散特性,对比了不同调制频率、微球腔直径、耦合损耗、传输损耗下与误差曲线斜率的关系.结果表明:耦合状态下最大Q值可达到1.1×108,调节微球腔内横磁模和横电模的转换可优化耦合效率,匹配微球腔和锥形光纤的尺寸得到了径向二阶模式的透射谱,误差曲线效率达到15.4A mW/MHz.球腔在提高PDH稳频技术灵敏度上具有巨大潜力.     

基于回音壁模式微球腔的PDH稳频技术（英文）

光学微球腔因其回音壁模式可获得极高的品质因数而受到广泛关注.本文分析了Fabry-Perot腔和微球腔的基本原理,通过CO2激光熔融光纤实验制得了直径为1.2mm的微球腔,并测试了微球腔和锥形光纤耦合结构的耦合特性.采用典型的PDH稳频系统设计了基于微球腔的稳频系统,分析了用于鉴频的误差曲线的吸收特性和色散特性,对比了不同调制频率、微球腔直径、耦合损耗、传输损耗下与误差曲线斜率的关系.结果表明:耦合状态下最大Q值可达到1.1×108,调节微球腔内横磁模和横电模的转换可优化耦合效率,匹配微球腔和锥形光纤的尺寸得到了径向二阶模式的透射谱,误差曲线效率达到15.4A mW/MHz.球腔在提高PDH稳频技术灵敏度上具有巨大潜力.     

基于飞秒激光直写的单向单模耦合微腔

对具有高Q值的回音壁模式微腔进行调制来获得单向单模输出,对研究腔光力学和开发高质量的微激光具有重要意义.本文对利用飞秒激光直写加工的耦合回音壁模式微腔的研究进行了简要回顾,具体介绍了微腔结构设计、加工过程、激射和耦合机制研究等.利用飞秒激光直写加工的强大三维图案化能力,灵活地设计实现了具有集成功能的单个微腔和具有不同空间组合位置的多个耦合微腔.基于耦合微腔的微激光具有低阂值,同时显示出良好的单模特性和单向性.结合理论模拟可以证实,微腔与微腔/光栅之间的耦合,一方面支持游标效应和集成滤波两种选模方式,另一方面能够破坏微腔的旋转对称性从而获得单向输出,从而实现了对微腔输出的有效调控.     

激光二极管端面连续抽运的Cr^4＋：Nd^3＋：YAG微片激光器输出特性研究

报道了腔长为1．1mm的激光二极管端面抽运的Cr^4 ：Nd^3 ：YAG自调Q微片激光器，连续抽运下获得了平均功率为5—18mW、重复频率为1—10kHz的稳定的调Q激光脉冲输出序列。并且对微片激光器的调Q输出激光的单脉冲特性参量、重复频率以及抽运阈值功率等进行了理论研究，计算结果和实验结果比较吻合。     

基于sol-gel法制备掺铒微腔激光器及其光学特性

用sol-gel法加工掺铒微环芯腔,得到品质因数高、模式体积小、非线性阈值低等优良光学特性的掺铒微环芯腔激光器.在精密三维调节-二维监控实验平台上对掺铒微环芯腔进行光纤锥倏逝场近场耦合实验.通过对耦合程度和泵浦源激光输入功率的调节,得微环芯腔的品质因数Q超过107.当泵浦源激光波长为1 444.44nm时,微环芯腔输出波长为1 450.54nm的激光,最大输出功率为3.00μW,泵浦源输入功率的最低阈值为10.5mW.     

光学微球腔及其应用

光学微球腔因其极高的品质因和极小的模式体积，在非线性光学、腔体量子电动力学以及窄带光学滤波、高灵敏度运动传感器、极低阈值激光器等许多研究与应用领域具有广泛的应用前景。文章对光学微球腔的谐振原理、特点、耦合、制备和应用进行了综述。     

光阴极注入器的驱动激光器

 光阴极注入器要求驱动激光器的激光时间抖动小、脉冲宽度窄、激光波长短和脉冲功率高。从原理和实验上介绍光阴极注入器的驱动激光器,包括连续波锁模振荡腔、时间同步,激光脉冲功率放大等;该激光器输出激光微脉冲宽度10ps,微脉冲时间抖动小于2ps,宏脉冲宽度2.5 μs, 峰值功率100kW, 已用于光阴极RF腔注入器实验,并获得了很好的结果。     

光泵浦低阈值聚合物激光器

高阈值是实现直接电驱动聚合物激光器的主要障碍。本文采用性能优异的蓝光材料-聚芴(PFO)作为激光增益介质,根据腔量子电动力学原理,设计出结构合理的平面光学微腔,通过减薄聚合物层厚度的方法进一步降低有源层材料自吸收;采用两种不同材料体系的分布布拉格反射镜(DBR)构筑光学微腔,减小顶部DBR制备过程中引入的额外光损耗,获得了低损耗、高Q值的光学谐振腔;有效调控PFO的自发发射和受激发射特性,最终实现了峰值波长位于443 nm、阈值仅为30 mW/cm~2的光泵浦低阈值聚合物激光器。     

外界环境对微球腔品质因数的影响

光学微腔由于其高品质因子(Q)特性具有广泛的应用前景.本文以光学微球腔为例分析了影响Q的各种因素,并通过实验研究分析了光学微球腔所处环境对Q的影响.选用直径约为260 μm的典型微球腔与锥形光纤进行耦合,通过透射谱的变化来反应Q的变化,结果表明,微球腔周围水蒸气的光吸收损耗和粉尘的散射损耗对微球腔的Q影响较大,能够导致...     

二极管泵浦双掺杂YAG微片自调Q激光器

 利用激光二极管泵浦双掺杂YAG微片晶体，在连续泵浦时获得了重复频率为2.78kHz，脉冲宽度为6ns的自调Q激光输出。并通过预泵浦加脉冲调制电流的方法，实现可控重复率的自调Q脉冲输出。与外腔式自调Q微片激光器相比，这种一体化微片激光器具有更高的转换效率、更窄的输出脉冲宽度和更高的重复频率，同时结构更为简单紧凑，易于调整。     

QUANTUM LANGEVIN THEORY OF WHISPERING-GALLERY-MODE MICROSPHERE LASER

A quantum Langevin theory of whispering-gallery-mode microsphere laser theory is developed. The linear and nonlinear analysis are made for laser operation below and above the threshold. In these analysis, corresponding to the specific property of microsphere, the effect of inversion fluctuation is treated. The coherence functions of laser field are calculated, and the intensity, the amplitude fluctuation and the linewidth of the field are obtained, which are connected with the enhancement factor of whispering-gallery-mode microsphere. It is shown that the strong couple and strong pumping are useful for the amplification of intensity and the decrease of linewidth below the threshold. It is also shown that, for the laser action above threshold, the variances of photon number and the linewidth of internal field are related to the enhancement factor and the square of the enhancement factor, respectively.     

一种激光损伤阈值测试新方法

随着激光器朝向大功率、高能量的方向发展,激光损伤阈值成为了衡量光学元件抗激光损伤能力的重要参数之一,因此,能否准确地测量出光学元件的激光损伤阈值成为研究的重点。而光学元件激光损伤阈值测试的关键是能否准确地判别光学元件是否发生激光损伤。为解决目前常见的损伤判别方法存在的精度低、识别时间长、适用材料范围窄、操作复杂等不足,提出了一种新的激光损伤的判别方法,即等离子体诊断法。以K9玻璃为例,搭建激光损伤阈值的测试平台,利用光纤光谱仪采集强激光辐照K9玻璃时所产生的激光等离子体闪光光谱,并对该光谱进行诊断分析,将该光谱中是否含有待测试光学元件材料中特征元素的光谱峰作为其是否收到激光损伤的标准。同时,对K9玻璃进行了激光损伤阈值的测试,并将测试结果与等离子体闪光法和显微镜法所测的激光损伤阈值进行了对比分析。实验表明,提出的等离子体诊断方法的判别精度高、速度快、测试装置结构简单,易实现在线测量,可以大大地提高光学元件激光损伤阈值测试工作的效率。     

Active Q switching of a fiber laser with a microsphere resonator

We propose and demonstrate an active Q-switched fiber laser using a high-Q microsphere resonator as the Q-switching element. The laser cavity consists of an Er-doped fiber as the gain medium, a glass microsphere reflector (coupled through a fiber taper) at one end of the cavity, and a fiber Bragg grating reflector at the other end. The reflectivity of the microsphere is modulated by changing the gap between the microsphere and the fiber taper. Active Q switching is realized by oscillating the microsphere in and out of contact with the taper. Using this novel technique, we have obtained giant pulses (maximum peak power approximately 102 W, duration approximately 160 ns) at a low pump-power threshold (approximately 3 mW).     

双谐激光场作用下SBS过程诱导的光学材料破坏

 提出了光学 力学相干耦合的概念，采用非线性光学的耦合波理论，建立了高功率激光辐照下透明光学材料中相干声波的产生、演化的动力学模型。探讨了在泵浦激光场和Stokes激光场共同作用下受激布里渊过程对光学材料破坏的可能性，计算了稳态情况下激光场在材料内部激发出的应力幅度，结合弹性力学，建立了透明光学材料的相干破坏阈值理论，研究了破坏阈值与Stokes光强的关系，发现在稳态下破坏阈值对Stokes光强并不敏感。分析了在实际情况下一些因素对材料破坏的影响。     

Surface ablation of congruent and Mg-doped lithium niobate by femtosecond laser

Lithium niobate is praised as silicon in nonlinear optics for its wide usage both in fundamental science and applications in optics. But its photorefractive effect hinders it from more extensive application in optics. The deadlock has been broken by doping some metallic elements such as magnesium into the congruent lithium niobate crystal for its high damage resistance. The single-shot and multi-shot surface ablation experiments by femotosecond laser with the wavelength of 800 nm and the duration of 80 fs were conducted in the same condition and the ablation threshold fluence was gained for congruent lithium niobate crystal and 6 mol % Mg-doped lithium niobate crystal. The band gap widening after doping is responsible for the discrepancy of the ablation thresholds between the two samples. The laser threshold fluence dependence of lasershot number demonstrates the difference of the accumulation effect. The large reduction of trapping cross section for electrons after heavy doping of magnesium is focused more to interpret this distinction.     

Development of multi-wavelength microsphere fibre laser system for potential sensor applications

A multi-wavelength microsphere laser system, using a chirped fibre Bragg grating and a microsphere resonator as wavelength-selective elements and a high dopant erbium doped fibre as the gain material, has been successfully demonstrated. The multi-wavelength generation of the laser system arises from both the microsphere whispering gallery mode selection and from the additional Raman scattering inside the microsphere cavity when the erbium laser is operating at resonance with the whispering gallery modes. Through an appropriate design and fabrication of a microsphere and of a fibre taper, a selective multi-wavelength fibre laser has been realized when the pump power is above threshold required. The laser output lines created have shown much narrower linewidths than those from conventional fibre lasers and these characteristics are particularly suitable for the range of sensor applications envisaged in the work.     

Highly efficient hybrid fiber taper coupled microsphere laser

A novel hybrid fiber taper is proposed and demonstrated as the coupler in a microsphere laser system. The pump wave and the laser emission, respectively, are more efficiently coupled to and from the sphere modes with this taper structure. A 980-nm pumped erbium-ytterbium codoped phosphate microsphere laser is demonstrated in the 1550-nm band. As much as 112microW of single-frequency laser output power was measured, with a differential quantum efficiency of 12%.     

用于飞秒紫外激光产生的LD泵浦高效Nd∶YVO_4绿光激光器研究

利用简单的折叠腔 ,腔内不含任何其它附加光学元件 ,LD双端泵浦 Nd∶YVO4 ,KTP腔内倍频绿光激光器实现了低阈值、高效率的 TEM0 0 模稳定激光输出 .最高绿光输出功率可达到 3 .3 W,光 -光转换效率为 1 6.2 % .