Temperature and gain dynamics in flashlamp-pumped Er:YAG

A novel optical transmission method was used for measuring transient temperature dynamics inside an Er:YAG laser crystal during optical pumping with flashlamp pulses of different duration and spectral composition. Time-resolved measurements of the crystal gain at 2.94 μm were also performed for the same set of pumping conditions. The results are compared with predictions of a theoretical model for gain and temperature dynamics during optical pumping of Er:YAG. A good spatial resolution of the implemented temperature measurement method was utilized also to determine the lateral temperature profiles inside the laser rod under various pumping conditions     

Evaluation of InGaAsP laser material by optical pumping

A novel technique based on optical pumping has been developed to evaluate InGaAsP laser material before it is processed into electrical devices. By pumping unprocessed InGaAsP chips with cleaved mirrors with a 1.06 μm wavelength Nd:YAG laser and detecting the light emitted by the quaternary active layer, various properties such as laser threshold, wavelength, and differential quantum efficiency can be determined. This technique provides a method for screening InGaAsP laser material prior to time-consuming processing. The technique is also applicable to partially processed laser chips, and hence, the effect of each processing step can be evaluated. We find that threshold pumping intensities andT_{0} (sim60degC), the parameter characterizing the temperature variation of threshold, are virtually the same for chips without and with a p-n junction or alloyed contact.     

YAG激光棒光泵浦动态热效应的干涉测试

本文研究了脉冲固体激光器的YAG激光棒光泵浦动态热效应对激光波面的影响。采用激光干涉测量方法得到了YAG激光棒在脉冲光泵浦时的瞬态干涉图和泵浦后的时间序列干涉图,并用计算机进行图像处理和计算,得到三维时间序列畸变波面图和激光棒的热焦距随时间变化的曲线。     

Two-mode optical pumping of a laser

The coherent optical pumping of a laser is investigated by means of semiclassical laser theory with the assumption that either the pump source or the laser output is multimode. All radiation modes are allowed to reach saturating levels. A multitude of interesting effects result from induced population pulsations. As a particular application we study numerically the optical pumping of a single-mode homogeneously broadened FIR laser with a two-mode pump. We find that at least for symmetric pumping higher FIR intensities can be obtained with two, instead of one, pump modes.     

Excited state absorption of pump radiation as a loss mechanism insolid-state lasers

The characteristics of optical pumping dynamics in laser-pumped, rare-earth-doped, solid-state laser materials are investigated by using a tunable alexandrite laser to pump Y₃Al₅O₁₂ :Nd³⁺ in an optical cavity. It is found that the slope efficiency of the Nd laser operation depends strongly on the wavelength of the pump laser. For pump wavelengths resulting in low slope efficiencies, intense fluorescence emission is observed from the sample in the blue-green spectral region. This is attributed to the excited-state absorption of pump photons which occurs during radiationless relaxation from the pump band to the metastable state. This type of process is an important loss mechanism for monochromatic pumping of laser systems at specific pump wavelengths     

An analysis of pulsation in coupled-cavity structure semiconductor lasers

Pulsation in a coupled-cavity structure (CCS) semiconductor laser, in which laser cavities are placed parallel with optical coupling between them, has been observed. The mechanism is simulated by solving rate equations for a model with two stripes of different emission energies. The pulsation in the simulation is based on the resonant oscillation, which originates in the nonlinear interaction between the electromagnetic field in the laser cavity and the population inversion, in cooperation with the perturbations caused by repetitively occurring optical pumping and quenching. Important parameters to define the properties of the pulsation are emission-energy difference, coupling coefficient, and excitation levels.     

Amplification and excited state absorption in longitudinally pumped laser dyes

Direct measurements of optical gain using a probe laser beam for the laser dye cresyl violet perchlorate (CVP) in methanol solution using longitudinal pumping at two different wavelengths are described. An analysis of these longitudinal pumping experiments is developed and analytical expressions relating measured gain to the measured pump laser transmission are presented. This analysis is developed in terms of relevant optical cross sections including the influence of excited state absorption. The results demonstrate the influence of excited state absorption at the pump wavelength on pumping efficiency and on the gain per pass at the probe laser wavelength.     

光抽运垂直外腔面发射激光器特性与研究进展

介绍了光抽运半导体垂直外腔面发射激光器的结构特点、设计原理及其性能优势,综合评述该领域的最新研究进展,并探讨该类型激光器的发展前景和技术发展方向.     

基于受激布里渊散射的自调Q掺铒光纤激光器简化模型

文中分析了在980nm低功率连续泵浦源泵浦的条件下基于瑞利(RS)受激布里渊散射(SBS)效应的掺铒光纤激光器的自调Q过程。根据泵浦功率与重复频率、有效单模光纤长度与输出功率、有效单模光纤长度与脉冲宽度(FWHM)以及光纤干涉环分光比与输出功率等关系,通过仿真得知单模光纤长度为10m和光纤干涉环分光比为70:30时的输出功率最大,得到了最佳有效单模光纤长度和最佳光纤干涉环分光比,优化了激光器结构参数,并建立了自调Q掺铒光纤激光器的简化模型。     

Spectroscopic and laser properties of Nd3+ in BIGaZLuTMnfluoride glass

The optical properties of Nd³⁺-doped fluoride BIGaZLuTMn glass have been investigated by using steady-state and time-resolved laser spectroscopy. Laser action has been obtained for the first time in this glass by flashlamp pumping. The influence of site-dependent effects on fluorescence lifetime and time-resolved stimulated emission has been proved     

Thermally induced whispering gallery mode laser in MEH-PPV solutions

We report on thermally activated whispering gallery laser modes of a solution of MEH-PPV conjugated polymer supported by a silica optical fiber. The viscosity of the polymer solution gives place to a thin shell of the gain solution around the fiber driven by capillary action. Whispering gallery modes (WGMs) are thermally induced by a decrease in the refractive index of the polymer solution under intense optical pumping. The laser emission is produced because the evanescent waves of the WGMs couple the surrounding gain medium. These results support the use of conjugated polymers in optofluidic laser systems and highlight the importance of physicochemical properties, such as viscosity and optically induced heating, on the performance of the devices.     

半导体激光泵浦Nd:YAG激光器技术研究

本文研究了半导体激光端面泵浦固体激光器中的主要技术,指出泵浦功率较低时,为了降低激光器的阈值应选用近半共心腔或大R腔;泵浦功率较高时,为了提高激光器的输出功率和转换效率应选用半共焦腔。泵浦光耦合系统的设计应满足与激光腔模的最佳模式匹配。当泵浦功率为86mW时,Nd;YAG激光器基模输出8.3mW;激光器阈值为12mW。     

New Strong MM FIR Emissions in CH2=CF2 Pumped by a Pulsed CO2 Laser

By pumping with a suitable pulsed CO₂ laser we have produced several strong MM laser lines in 1,1 difluoroethene. All the emissions are easily identified because the emission spectroscopy is simplified in pulsed optical pumping.     

超短行波放大自发辐射的研究

用泵浦能量具有梯度分布的横向同步泵浦方案,产生超短行波自发辐射光脉冲。以N_2激光为泵浦源,获得约50ps的染料光脉冲输出,以锁模Nd:YAG倍频光作泵浦源,获得8～15ps光脉冲。用条纹照相机和光学多道分析器测量了脉冲波形和光谱。 计算机模拟了行波放大自发辐射的瞬态行为,计算结果与实验结果相符合。     

LD端面泵浦的高重频Nd:YAG激光器的热效应研究

在LD端面泵浦的高重频Nd：YAG激光器的光泵浦过程中产生的热效应是影响激光输出特性和系统综合性能的重要因素。从热传导方程入手,利用有限元法求得激光晶体中温度稳态分布的数值解,同时对其热透镜效应进行了计算分析,在此基础上运用传播圆一变换圆的图解分析法进行热稳腔的分离参数设计以补偿热透镜效应。该研究为进一步优化激光器设计,提高激光输出的稳定性奠定了基础。     

CW laser at room temperature using vitreous substances

With the aim of finding laser glasses operating in CW at room temperature, a comparative study was made of various neodymium-doped vitreous substances: silicate, borate, germanate, phosphate, and fluoride glasses. About 500 samples of phosphate glasses, doped with neodymium, were prepared and their optical properties studied. The phosphate glasses have three main advantages for laser action. 1) The fluorescence band is narrower than in silicate glasses and can be as sharp as 153 Å. 2) The optical pumping is more efficient in phosphate glasses. 3) The lifetime of the 4F3/2level is about 300 μs. The phosphate glasses have very interesting laser characteristics, i.e., in pulsed operation the threshold is 1 joule. Such a rod exhibits semicontinuous operation at room temperature pumped by a krypton arc lamp; when excited in ac, the threshold is about 1 kW. It was found that the fluoride glasses have even more promising laser properties.     

Tunable and narrow linewidth multi-wavelength Brill- ouin-erbium fiber laser using dual-wavelength pumping

We demonstrate a multi-wavelength Brillouin-erbium fiber laser (BEFL) with narrow linewidth and tunable wavelength interval using dual-wavelength Brillouin pumping. The generation of multi-wavelength output in BEFL is based on the combination of stimulated Brillouin scattering (SBS) and four-wave mixing (FWM) effect in a fiber cavity. The tunable wavelength interval is determined by the artificially controlled wavelength interval of the pumping lasers. The BEFL could compress a 1 MHz pump laser to a 340 Hz Brillouin Stokes laser, which proves the BEFL has excellent capability of linewidth compression. An erbium-doped fiber pumped by 980 nm laser is inserted into the cavity to further amplify the Brillouin laser. The wideband multi-wavelength BEFL covering over 50 nm is successfully generated when the 980 nm pump power is 400 mW. These features of multi-wavelength BEFL provide an effective method for optical communication systems and optical fiber sensing.     

Optimization of the optical output in a C-to-C pulsed gas laser

An investigation of the optimum condition for maximum optical output in a C-to-C pulsed gas laser (N₂ laser) showed that this condition does not happen when the two capacitances are equal (C ₁=C₂) as this happens in the “Doubling circuit” case, but when the peaking capacitance obtains a critical value. This behavior is attributed to the electric pumping pulse formed by the temporary loading of the peaking capacitor. This electric pumping pulse increases as the peaking capacitor increases. However, for low values of the peaking capacitor the optical output follows the rise of the electric pumping pulse. On the other hand, for higher values of the peaking capacitor than a critical one, a part of the electric energy arrives at the laser channel after the laser output, while the exploitable electric energy decreases causing reduction of the optical output     

二极管侧面泵浦固体激光器TEM00模输出研究

针对大功率二极管 (LD)侧面泵浦固体激光器的光耦合及泵浦结构方面的问题 ,我们设计了一套相应的高效光耦合系统及三个二极管 1 2 0°对称泵浦的结构系统。在此基础上 ,实现了高重频、高效率的 TEM0 0 模激光输出。     

Resonating properties of passive spherical optical microcavities

As an optically pumped device, the lasing characteristics of a spherical microcavity laser depend on the optical pumping processes. These characteristics can be described in term of the Q factor and the optical field distribution in a microsphere. We derived analytical expressions and carried out numerical calculation for Q factor and optical field. The Q factor is found to be oscillatory functions of the radius of a microsphere and the pumping wavelength, and the pumping efficiency for a resonating microsphere is much higher than that for an anti-resonating microsphere. Using tunable lasers as pumping sources is suggested in order to achieve a higher pumping efficiency. Numerical calculation on optical field distribution in spherical microcavities shows that a well focused Gaussian beam is a suitable incident wave for cavity quantum electrodynamics experiments in which strong confinement of optical field in the center of a microsphere is requested, but higher order spherical wave should be used instead for exciting whispering-gallery-mode (WGM) microsphere lasers, for the purpose of favoring optical energy transferring to WGM in optical microspheres.