𝒬-switched neodymium-doped phosphate glass fiber lasers

The operation of a short-pulse, 𝒬-switched, neodymium-doped fiber laser operating at 1.054 μm is described experimentally and theoretically. The laser is efficiently pumped with a single-stripe AlGaAs laser diode and emits >1 kW pulses. It is seen that due to high gain short pulses with high energy extraction efficiency can be obtained. The feature of broad emission lines associated with rare-earth-doped glasses is exploited to demonstrate tunable, 𝒬-switched operation over a 40-nm tuning range     

Bend loss in neodymium-doped fiber lasers

This paper is concerned with the effect of a fixed radius bend upon the operation of a neodymium-doped fiber laser at a wavelength of 1064 nm. In particular, the threshold power, slope efficiency, and cavity lifetime were measured over a range of bend radii and lengths. Oscillations were observed in the variation of the experimentally measured laser parameters with bend length over a range of bend radii which was explained by the finite thickness of the cladding. The results are explained theoretically with the aid of a model in which the pure bend loss coefficient is a parameter in the relevant laser equations and the finite thickness of the cladding is taken into account     

Fabrication of optically nonlinear semiconductor mirrors for modelocking of neodymium-doped fiber lasers

A recipe is given for an all-semiconductor, optically nonlinear mirror for passive modelocking of neodymium-doped fiber lasers. InGaAs-GaAs quantum wells (QWs) are used for a saturable absorber. It was empirically found that the best modelocked operation occurred when QWs had a heavy-hole excitonic absorption peak at a wavelength about 10-20 nm longer than the lasing wavelength. An AlAs-GaAs quarter-wavelength stack is used for a rear high reflector. Nonlinear mirrors are etched after epitaxial growth so that the lasing wavelength coincides with a reflectance maximum, giving maximum optical modulation. Nonlinear mirrors are implanted with large doses (2/spl times/10/sup 15//cm/sup 2/) of hydrogen ions in order to increase electron-hole recombination rates, speed material recovery, increase saturation intensity, and inhibit spontaneous Q-switching. Studies of material growth by molecular beam epitaxy and metal-organic chemical vapor deposition (MOCVD) are reported. Modelocked fiber lasers exhibited a pseudorandom output that was produced by several optical pulses that circulated simultaneously in the fiber. It was found that a very high reflectance mirror is not required for lasing or modelocking. To our knowledge, this is the first report of the use of a nonlinear mirror grown by MOCVD to modelock a neodymium fiber laser.     

掺Nd3+玻璃微球阵列激光器的热学性能研究

为了研究二极管阵列抽运折射率匹配液冷却的掺Nd3+玻璃微球阵列增益区产生的热效应,采用FLUENT6.3.26软件建立了激光器增益区流场的热-流-固耦合模型,利用有限元分析法,模拟分析了钕玻璃微球阵列的温度分布与自身尺寸、匹配液流速、微球层数和抽运频率的变化关系及其对热畸变的影响。由模拟结果可知,固体微球激光器的热恢复时间短,冷却效果与微球层数无关,流速增加对小尺寸微球的冷却效果无明显改善;当抽运频率为1Hz时,直径为2mm和4mm的微球增益区的单程最大光程差为3.1nm和51.9nm。结果表明,该构型激光器具有高效的冷却能力。这一结果对微球阵列激光器的热管理是有帮助的。     

High-gain superfluorescent neodymium-doped single-mode fiber source

High-brightness, low-coherence sources are required in a number of optical sensor applications, particularly the fiber-optic gyro. An efficient superfluorescent, neodymium-doped phosphate glass fiber source has been developed which fulfils this requirement. The fiber shows a high-gain efficiency at 1.053 μm of 1 dB/mW pump power and this permits pumping with an 810 nm single-stripe AlGaAs laser diode to obtain >5 mW CW output power at a wavelength of 1.053 μm for only 45 mW of pump power     

Spectroscopic properties and efficient diode-pumped laser operationof neodymium-doped lanthanum scandium borate

We report on the spectroscopic properties and laser performance of Czochralski-grown LaSc₃(BO₃)₄ (LSB) crystals with high neodymium concentrations up to 2.5·10²¹ cm^-3. The low-concentration quenching of the upper laser level of neodymium and the polarization dependence of the spectra indicate that LaSc₃(BO₃)₄ crystalizes in a huntite-type structure like Nd³⁺:YAl₃(BO₃)₄ (NYAB). With diode laser pumping at 808 nm, a multimode Nd³⁺:LaSc₃ (BO₃)₄ (NLSB) laser at 1063 nm is demonstrated. Optical slope efficiency was 64% with respect to absorbed pump power. The possibility of second-harmonic generation in the laser crystal is discussed     

高功率光纤激光器用20/400双包层掺镱光纤

采用改进化学气相沉积结合溶液掺杂法制造出了掺镱石英光纤预制棒,预制棒轴向上芯径波动小于5%,折射率差波动小于8%。研磨加工后拉制出20/400双包层掺镱光纤,光纤纤芯不圆度为2%,芯包同心度偏差为0.87 μm。双包层掺镱光纤在1095 nm的包层损耗为2.1 dB/km。采用拉制的掺镱双包层光纤作为直接振荡结构全光纤化激光器的增益光纤实现了1195 W的1080 nm激光输出,斜率效率达82%。     

掺钕双频微片激光器功率均衡实验研究

为了探究掺钕晶体对激光器功率均衡机制的影响 ,实验对不同参数的掺钕晶体双频微片激光器进行了功率均衡实 验研究。在实验中,通过改变抽运功率和调节热沉温度等手段,研究了双频微片激光器功率 在均衡状态时,热沉温度、 抽运功率和双频激光功率积等参数之间的关系。研究结果表明:对于功率均衡的掺钕双频微 片激光器,当抽运功率增加 时,热沉温度随之降低且与之呈负相关,需要降低热沉温度以实现双频激光的功率重新均衡 ;重新均衡后的双频激光波 长与频差不随抽运功率的变化而变化;功率均衡的双频激光功率积随抽运功率的增大而增大 ,且呈正相关。此结果说明 对于不同参数的掺钕晶体双频微片激光器,均可通过改变抽运功率和热沉温度可以实现功率 可调的功率均衡的双频激光 信号输出。这种输出功率可调谐的双频微片激光器在光生毫米波等领域有较大用途。     

掺Nd石英单模光纤1.088μm连续光纤的激光特性

实验中所用光纤是一根长为2.7m,芯径为5m的掺Nd单模石英光纤。光纤在激光波段的损耗～10dB/m,在514.5nm处的吸收损耗分别约为50dB/m和100B/m。     

Pulse length and terminal-level lifetime dependence of energyextraction for neodymium-doped phosphate amplifier glass

On the basis of detailed numerical calculations, we have formulated an empirical expression for the saturation fluence in neodymium-doped phosphate amplifier glass that explicitly depends upon the ratio of the pulse width to the terminal-level lifetime. The empirical expression, when substituted within the Frantz-Nodvik solution for energy extraction, can be used to determine the impact of the lower level lifetime on the energy extracted from Nd:phosphate glass amplifiers. We used our empirical solution to model experimental gain-saturation data and determine the terminal-level lifetime. We compared this value with two independent experiments and found that all three experiments yielded similar results. The terminal-level lifetime of LG-750 at room temperature is found to be 253 ps ±50 ps     

Tm-doped mode-locked fiber lasers

Ultrashort pulse fiber lasers are increasingly used in various areas for scientific as well as industrial purposes. In contrast to ultrashort pulse lasers based on ytterbium- and erbium-doped fibers, the dispersion of silica fibers in the amplification band of thulium-doped fibers around 2 μm is typically anomalous, which has fundamental impact on the pulse propagation. In this paper, mode-locked thulium-doped fiber lasers operating in different pulse propagation schemes are presented. The transfer of various concepts into the 2 μm wavelength range, which have been successfully applied for pulse parameter scaling in the 1 and 1.5 μm spectral region, are discussed on the basis of experimental and numerical results.     

光纤激光器的应用

作为第三代激光技术的光纤激光器由于采用了双包层分叉光纤和高功率的多模半导体二极管，输出功率已经实现10000W，应用范围已突破狭窄的光纤通讯网络，在激光加工、激光医疗等行业得以日益广泛的应用。光纤激光器具有绝对理想的光束质量、超高的转换效率、完全免维护、高稳定性以及体积小等优点，将对传统的激光行业产生巨大而积极的影响，从而改写光应用的历史篇章。     

High-power double-clad fiber lasers

Rare-earth doped, laser-diode-pumped, single-mode, double-clad fiber lasers are studied in detail, experimentally and theoretically, with particular attention to properties of scaling to higher output powers. Gain saturation, spontaneous emission, fiber propagation loss, and the optimum output coupler are considered for oscillator design and laser performance. Thermal properties are investigated, including the thermal fracture limit, the decrease of quantum efficiency with increasing pump power through the temperature dependence of multiphonon decay and ion-ion energy transfer, and thermal lensing. Self-focusing and Raman effects are briefly considered. It is shown that output powers in the tens of watts range are readily feasible with available double-clad fiber lasers     

光子晶体光纤激光器

结合光子晶体光纤简述了光子晶体光纤激光器的类型、结构及性能 ,介绍了光子晶体光纤激光器的研究进展和应用前景     

Strongly pumped fiber lasers

Strongly pumped fiber lasers are analyzed, based on a rate equation model. Examples include Nd³⁺-doped and Yb³⁺ -doped fiber lasers, with distributed Bragg reflector mirrors at either end. Approximate analytical and quasi-analytical expressions are shown to be in excellent agreement with the exact numerical solution of the rate equations, and both agree well with recently published experimental data     

Midinfrared holmium fiber lasers

The use of the high-power Tm/sup 3+/-doped silica fiber laser as a pump source for Ho/sup 3+/-doped silica and Ho/sup 3+/-doped fluoride fiber lasers for the generation of 2.1-/spl mu/m radiation is demonstrated. The Ho/sup 3+/-doped silica fiber laser produced a maximum output power of 1.5 W at a slope efficiency of /spl sim/82%; one of the highest slope efficiencies measured for a fiber laser. In a nonoptimized but similar fiber laser arrangement, a Ho/sup 3+/-doped fluoride fiber laser produced an output power of 0.38 W at 2.08 /spl mu/m at a slope efficiency of /spl sim/50%. A Raman fiber laser operating at 1160 nm was also used to pump a Ho/sup 3+/-doped fluoride fiber laser operating at a wavelength of 2.86 /spl mu/m. An output power of 0.31W was produced at a slope efficiency of 10%. The energy transfer upconversion process that depopulates the lower laser level in this case operates at a higher efficiency when the pump wavelength is closer to the absorption peak of the /sup 5/I/sub 6/ energy level, however, this energy transfer process does not impede to a great extent the performance of the Ho/sup 3+/-doped fluoride fiber laser based on the /spl sim/2.1/spl mu/m laser transition.     

Simultaneous measurements of lifetime, gain and emission crosssection in a neodymium-doped fiber

A method for measuring the gain and the emission cross section of the four-level neodymium system in doped waveguides is presented. The method is based on a temporal analysis of the fluorescence decay occurring when the pump is switched off, after establishing a steady-state with high levels of absorbed power. For the case of doped fibers, results obtained using this method are compared with the usual low signal amplification technique, using a launched signal in the fiber, and the agreement is good. It is shown that the technique allows a rapid, simple method of determining low signal gain     

光纤激光器的相干合成技术

介绍了光纤激光器相干合成的研究现状,分析了几种典型的相干合成方法,指出了最佳的相干合成方法。     

高功率光纤激光器

1、引言。所谓高功率光纤激光器是相对于光纤通讯中作为载波的低功率光纤激光器而言(功率为mW级)，是定位于机械加工、激光医疗、汽车制造和军事等领域的高强度光源。高功率光纤激光器巧妙地将光纤技术与激光原理有机地融为一体，铸造了21世纪最选进和最犀利的激光器。即使是在激光技术发达的国家，光纤激光器也是尖端、神秘和充满诱惑的代名词、2002年6月，光纤激光器空降中国，震撼了中国激光学术界和产业界，并引起了至尊院士的关注。