Fiber Optic Coupling of CW Linear Laser Diode Array

Based on a set of microoptics the output radiation from a continuous wave (CW) linear laser diode array is coupled into a multi-mode optical fiber of 400 μm diameter.The CW linear laser diode array is a 1 cm laser diode bar with 19 stripes with 100 μm aperture spaced on 500 μm centers.The coupling system contains packaged laser diode bar,fast axis collimator,slow axis collimation array,beam transformation system and focusing system.The high brightness,high power density and single fiber output of a laser diode bar is achieved.The coupling efficiency is 65% and the power density is up to 1.03×104 W/cm2.     

Fiber Optic Coupling of CW Linear Laser Diode Array

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侧面抽运的掺Yb双包层光纤激光器

利用光纤角度磨抛侧面耦合新技术研究了侧面抽运的掺Yb双包层光纤激光器。实验上采取新的加工工艺获得了端面具有小锐角磨抛斜角的多模光纤,专门设计的高精密机械调整结构有效地将多模光纤的斜面和双包层光纤的侧面精确对准,通过不同的折射率匹配材料进行的研究,发现折射率匹配材料对于注入功率和抽运效率都有较大影响。实验中通过光纤角度侧面耦合器能够注入1．12W抽运光进入双包层光纤,侧面耦合效率最高可达80％。将该侧面耦合技术用于侧面抽运的掺Yb双包层光纤激光器,在单个尾纤输出的半导体激光器侧面抽运下得到光纤激光器的最大连续激光输出功率282mW,斜率效率为55．5％。实验结果表明,光纤角度磨抛耦合技术是掺Yb双包层光纤激光器的一种简单有效的侧面抽运方式。     

InGaAsP/GaAs SCH SQW laser arrays grown by LPE

InGaAsP/InGaP/GaAs separate confinement heterostructure (SCH) single quantum well (SQW) laser structures have been obtained by an improved liquid-phase epitaxy (LPE) process. Wide-contact stripe lasers have been fabricated with threshold current density below 300 A/cm² and cavity length of 800 μm. Finally, with the same grown wafers, 1-cm bar laser diode (LD) arrays are made with 150 μm wide stripes and a maximum fill factor of 30%. Continuous Wave (CW) power output of 20 W has been reached.     

包层泵浦的铒镱共掺光纤激光高效产生的实验研究

利用尾纤输出的977nm高亮度多模半导体激光器包层泵浦铒镱共掺双包层光纤,采用非球面透镜组耦合方式,使泵浦耦合效率达66%以上,并在法布里-珀罗激光振荡腔结构中实现了高效的连续激光产生,双包层光纤长度为2m,在泵浦入纤功率为1.36W时,输出连续功率最大394mW,斜率效率达35%,激光输出波长1.565μm.     

双包层光纤光栅选频双包层光纤激光器

双包层光纤激光器中多采用法布里珀罗(F-P)线形腔结构,谐振腔为一只二向色镜和光纤端面菲涅耳反射镜(反射率约为4％)构成,这属于一种有缺陷的腔结构,其稳定性不好,产生激光的波长很难得到有效控制,后腔镜不能精确选择激光器的输出波长,激光器的输出谱线较宽。在某些对激光波长有明确要求的应用中,该结构会受到限制。采用布拉格光纤光栅作腔镜,利用其窄带滤波特性,可以得到窄线宽的激光输出,目前报道的作为腔镜的布拉格光纤光栅为在单包层光敏光纤上制作而成,然后分别将不同反射率的光纤光栅与双包层增益光纤熔接,这给腔镜与双包层光纤之间带来很大的耦合损耗,影响了激光器的功率输出。该文报道了用相位掩模法在双包层光纤芯上写入了布拉格光纤光栅,并把此光纤光栅做为后腔镜．对长度为10m、20m的D形掺Yb^3 双包层光纤激光器进行实验研究,在1058nm附近得到稳定的窄线宽激光输出,3dB带宽为0．329nm。激光器最大输出功率为570mW。最后对实验结果进行了理论分析。     

窄线宽线形腔调Q双包层掺钕光纤激光器

对LD泵浦调Q双包层掺Nd³⁺光纤激光器进行了实验研究.在Littrow结构的体光栅与二向色镜构成的线形腔结构中,利用声光Q开关(AQM)调Q,在1064nm得到了光谱线宽约为0.08nm稳定的激光脉冲序列.脉冲重复频率从1kHz到10kHz可调.在重复频率1kHz时得到脉冲宽度约800ns,最大单脉冲能量180μJ,脉冲峰值功率225W,激光平均功率180mW,并对激光输出脉冲能量进行了计算,计算结果与实验符合很好.     

基于组合模理论设计的激光二极管阵列外腔

针对激光二极管阵列提出了"组合模"概念,计算了组合模的远场分布.每个组合模在远场的空间分布呈双瓣结构.基于激光二极管阵列组合模的远场分布特征,设计了离轴外腔反馈的激光二极管阵列.运用此装置所获得激光二极管阵列的远场分布有了明显变化.与自由运转的激光二极管阵列相比,离轴外腔反馈的激光二极管阵列远场宽度减少了4.3倍.在抽运电流为16 A时,测得输出激光的功率1.82 W,这相当于相同电流下自由运转激光器输出功率的79%.组合模理论不仅可以用来指导设计一维离轴外腔反馈激光二极管阵列,而且也可以用于设计二维离轴外腔反馈激光二极管阵列.二维离轴外腔反馈激光二极管阵列可以产生高功率,高光束质量输出的激光.     

Efficient double-clad Yb3+-doped silica fibre laser pumped by an unfocused diode laser

A moderate output power Yb³⁺-doped double-clad fibre laser pumped by an unfocused diode laser is reported. This pumping configuration omits micro positioned lenses used in fibre coupled laser diodes, thus making the system significantly less complex and more robust. The maximum launch efficiency was ～80% and the maximum output power was >5 W with a measured FWHM of 18 pm.     

Characterization of an Intra-Cavity Pumped P2O5-Doped Silica Raman Fiber Laser

We examine the characteristics of a P₂O₅-doped Raman fiber laser pumped by a double-clad ytterbium-doped fiber laser in an intra-cavity configuration. The double-clad fiber laser consists of two high reflection fiber Bragg gratings at 1092 nm, with an active length of 17 m, where the output grating is located at the end of the 400m P₂O₅-doped fiber. The Raman cavity is formed by a 1278-nm-high reflection fiber Bragg grating spliced to the double-clad fiber, and a 50% output coupler. The maximum conversion efficiency at 1278 nm with respect to the input pump power at 915 nm was 26.9%.     

基于平行玻璃板的半导体激光器阵列光束整形

为得到质量均衡的大功率激光束,分别以条形和面阵半导体激光器为模型,基于平行玻璃板对光束的偏移作用,对准直后激光束进行分割和重排,并在Zemax软件中进行了仿真。条形半导体激光器初始发散角为40和10,整形前已准直光束快慢轴方向的光参数积分别为0.455 2 mmmrad和20.484 mmmrad,光束质量相差较大,整形后快慢轴方向光参数积分别为2.731 2 mmmrad和3.414 0 mmmrad,实现了快慢轴方向光束质量均衡。利用平行玻璃板消除面阵半导体激光器中存在的发光死区,整形后快慢轴方向光参数积分别为7.002 mmmrad和10.242 mmmrad ,整形系统耦合效率为90.13%。     

Violet light generation by frequency doubling of GaAlAs diode laser using a metallo-organic complex crystal ZnCd(SCN)4

Violet 404-nm radiation is generated by type-I single-pass frequency doubling of the output of an GaAlAs diode laser in critically phase-matched ZnCd(SCN)₄ (ZCTC) crystal, a metallo-organic complex crystal. In this paper, its refractive index and second-harmonic generation phase-matching angles are reported. Using a 3-mm-long ZCTC crystal, a diode laser power of 473 mW generated 390 μW of second-harmonic radiation. More recently, 380-nm, 20 μW ultraviolet (UV) radiation is also realized by frequency doubling of the 100 mW output of a continuous-wave Ti:sapphire laser at 760 nm. ZCTC is a promising UV nonlinear optical candidate material for frequency doubling of diode lasers.     

多线阵半导体激光器的单光纤耦合输出

设计并研制了一种多线阵半导体激光器的高亮度光纤耦合输出模块.激光器芯片采用了分子束外延方法生长的宽波导、双量子阱结构AlGaAs/GaAs激光器外延材料,激光器模块采用6只准直的线阵半导体激光器,器件腔长为1.2 mm,单个发光单元宽度为100 μm,发光单元周期为500 μm,单线阵器件包括19个发光单元,单线阵器件的连续输出功率为50 W,每只单线阵器件的准直输出光束经过空间合束后再通过光束对称化变换实现了多线阵器件输出的高光束质量功率合成,采用平凸柱透镜实现了合束光束与400 μm芯径、数值孔径0.22石英光纤的高效率耦合,整体耦合效率达到65%,最大耦合输出功率达到195 W,光纤端面功率密度达到1.55×105 W/cm2.     

High-power Yb-doped multicore ribbon fiber laser

A highly elongated double-clad ribbon fiber that comprises a pure-silica inner cladding with transverse dimensions of approximately 1.4 mm by 0.23 mm with a linear array of ten ytterbium-doped cores has been fabricated and operated in a simple laser configuration pumped by two diode stacks. The fiber laser yielded 320 W of output power at a center wavelength of 1045 nm in a combined beam with beam propagation factors of approximately 2 (perpendicular to the array) and approximately 150 (parallel to the array) for 576 W of launched pump power. The slope efficiency with respect to absorbed pump power was 62%. The prospects for further power scaling and improved beam quality and efficiency are discussed.     

Multi-Wavelength-Switchable Double Clad Yb3+-Doped Fiber Laser Based on Reflectivity Control of Fiber Bragg Gratings by Induced Bend Loss

We propose and demonstrate an all-fiber multi-wavelength switchable double-clad Yb³⁺-doped fiber laser based on the reflectivity cavity control by induced bend loss. The wavelength switching is realized by a variable reflecting mirror that employs a cascaded array of three high reflection (>99%) fiber Bragg gratings at 1064, 1080 and 1096 nm, with a bending controller inserted between each grating. The order of the Bragg gratings is decided according to the gain profile of the Yb³⁺-doped fiber and the induced bending loss allows us to select the Bragg-wavelength laser operation. The laser is capable of switching continuously from one wavelength to another, and slope efficiencies over 50% are obtained at each wavelength.     

Multiple Beam Scanning Optics for Laser Printer: Application of Optical Fiber Array Method

We have developed laser printer optics using various kinds of multiple beam generation devices, such as a polarization prism, grating, diode laser array, and optical fiber array. Recently we successfully demonstrated laser-print experiments using five beams from an optical fiber array. In the array, fibers are arranged with a spacing of 0.15 mm and emit circular Gaussian beams that have a diameter of 5 μm and a wavelength of 635 nm. The wavelength of diode lasers is determined from sensitivity of the photoconductor drum of As₂Se₃ material. The arrangement error vertical to the array is mostly suppressed below 0.4 μm. In the optics, curve of scan lines and print position errors in the scan direction are suppressed to a negligible size due to minimization of the magnification variation in the sub-scan direction along the print width and achromatized design, respectively.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

Negative Nonlinear Absorption Effect for 1.5 μm Laser in an Erbium Chloride Solution

The dependence of the negative nonlinear absorption effect on both modulation degree and frequency of the incident laser was investigated in an erbium chloride solution using a 1.5μm laser diode. The reversed-phase waveform was observed at modulation degrees smaller than 71%. As modulation frequency increased, the transmitted waveforms became asymmetrical and the effect was suppressed. The effect was obtained at wavelengths of 1510.3 to 1510.8 nm. The negative nonlinear absorption effect for 1.5 μm. can be explained by considering an enhanced absorption model for a four-level system of the Er³⁺ ion.     

Q-switching of a diode-pumped Nd : YVO4 laser with GaAs nonlinear output coupler

Passive Q-switching of a diode-pumped Nd : YVO₄ laser was demonstrated using GaAs as an output coupler and as a saturable absorber. When pumped with a 3-W diode laser at 809 nm, the highly compact laser produced 12-μJ pulses of 2.2 ns in duration at 1.064 μm in a single transverse mode, corresponding to a peak power of 5.6 kW.     

Laser output power over 5 W at 1.06 μm for Nd:GdVO4 single crystal

In this paper, we report the polarization absorption spectra from 400 to 850 nm, polarization emission spectra from 1050 to 1100 nm and laser properties of an Nd:GdVO₄ crystal. An output power of up to 5.29 W at 1.06 μm has been achieved with a 3×3×3 mm Nd:GdVO₄ crystal sample when it is pumped by a cw laser diode.     

包层泵浦掺镱光纤激光器的理论和实验研究

从包层泵浦光纤激光器的速率方程理论出发,推导出了稳态下包层泵浦光纤激光器的输出功率,斜率效率和阈值功率的解析表达式,进行了数值模拟,对模拟结果进行了简单分析。并进行了实验研究,实验采用中心波长为975nm的激光二级管单端泵浦内包层形状为D型的包层光纤,利用二相色镜和光纤端面反馈构成谐振腔,采用了两套不同的准直耦合系统,得到的最高输出功率为24W,总的光-光转换效率为53.5%。