High-pressure behaviour of an X-ray preionized discharge pumped XeCl laser

The output characteristics are described of an X-ray preionized discharge pumped XeCl laser, fed by a low-impedance pulse forming line (PFL), at pressures up to 12 bar. The influence of a multichannel rail gap placed between the PFL and the laser head on the output energy was studied. We found an increase of output energy with increasing pressure up to 8 bar. At higher pressures a saturation behaviour was found. The maximum output energy per unit volume was 6.5 J/l.     

Compact, efficient diode-end-pumped Nd:GdVO4 slab continuous-wave 912-nm laser

A fiber-coupled laser-diode (LD) end-pumped Nd:GdVO₄ slab continuous-wave (CW) 912-nm laser and an LD bar end-pumped Nd:GdVO₄ slab CW 912-nm laser are both demonstrated in this paper. Using the fiber-coupled LD of end-pumped type, a highest CW 912-nm laser output power of 10.17 W is obtained with a high optical-to-optical conversion efficiency of 24.6% and a slope efficiency of 34.5%. The measured M² factors of beam quality in x and y directions are 5.3 and 5.1, respectively. Besides, an LD bar of end-pumped type is used to realize CW 912-nm laser output, which has the advantages of compactness and low cost. When the pump power is 38.8 W, the output power is 8.87 W and the measured M² factors of beam quality in x and y directions are 16 and 1.31, respectively. In order to improve the beam quality of the 912-nm laser at x direction, a new quasi-concentric laser resonator will be designed, and an LD bar end-pumped Nd:GdVO₄ slab high-power CW 912-nm TEM₀₀ laser will be realized in the future.     

Design of an Optical Fiber Device for Pumping a Double-Clad Fiber Laser with a Laser Diode Bar

Pumping of a rare-earth-doped double-clad fiber laser with a GaAIAs laser diode bar requires imaging the near field output of a 1 cm long one-dimensional linear array of tens of multi-mode laser diode sources onto a two-dimensional oblong cross section approximately matching the fiber’s first cladding shape. This work describes the design and preliminary implementation of a device (here called a high brightness geometric transformer) that achieves this transformation with minimum brightness loss. This is done by imaging the laser diode bar near field using a fast cylindrical micro-lens onto a linear array of N (≈10) soft-glass, thin-clad rectangular fibers; in turn, the fibers’ output ends are arranged to form a stack that matches the required first cladding shape. For a typical 20W CW, laser diode bar with brightness of 25 mW·μm²·sr^-1, the geometric transformer output brightness is 0.6 mW·μm^-2·sr⁻¹, i.e., there is a ·40 intermediate loss of brightness. If the output of the geometric transformer is used to pump a Nd-doped double-clad fiber laser, an overall brightness gain of ·340 can be achieved.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.     

高功率半导体激光泵浦源研究进展

高功率半导体激光器是固体激光器和光纤激光器的主要泵浦源。激光泵浦源性能的大幅提升直接促进了固体激光器、光纤激光器等激光器的发展。主要介绍了8xx nm和9xx nm系列半导体激光泵浦源的最新研究进展,8xx nm单管输出功率已达18.8 W@95μm,巴条输出功率已达1.8 kW(QCW),9xx nm单管输出功率已达35 W@100μm,巴条输出功率已达1.98 kW(QCW)。谱宽<1 nm的窄谱宽半导体激光器输出功率可达14 W。展望了未来半导体激光器泵浦源的发展趋势。     

Beam concentration and homogenization for high power laser diode bar

A novel optical element is presented and applied for beam concentration and homogenization of laser diode (LD) bar. It consists of a tapered SiO₂-rod with twisted surfaces which is designed and optimized by the optical system design software and fabricated by a curved surface grinder and an optical polishing lathe. Results show that a rectangular output beam spot with uniform intensity distributions both at slow and fast axis is obtained at the output facet of the rod and the beam size is only 1.3 mm ∗ 0.8 mm.     

高效连续波钛宝石激光器的优化设计及实验研究

运用ABCD律及自再现条件对钛宝石线性腔的折叠角进行了优化,从而大大提高了钛宝石晶体中光束束腰的耦合效率同时实验上对连续钛宝石激光器进行了研究,采用20mm长的钛宝石晶体和10%输出耦合镜,并运用优化后的折叠角,最终用全线氩离子激光器泵浦的连续波钛宝石激光器的斜率效率高达34.2%,在泵浦功率为7.7W下,连续钛宝石激光器输出功率达1.89W.     

High Power All-Solid-State Nd: YVO_4 laser and its intracavity SHG

Ｈｉｇｈ　Ｐｏｗｅｒ　Ａｌｌ－Ｓｏｌｉｄ－Ｓｔａｔｅ　Ｎｄ：ＹＶＯ＿４　ｌａｓｅｒ　ａｎｄ　ｉｔｓ　ｉｎｔｒａｃａｖｉｔｙ　ＳＨＧＨｉｇｈＰｏｗｅｒＡｌｌ－Ｓｏｌｉｄ－ＳｔａｔｅＮｄ：ＹＶＯ＿４ｌａｓｅｒａｎｄｉｔｓｉｎｔｒａｃａｖｉｔｙＳＨＧ￥ＺＨ...     

LED pumped polymer laser sensor for explosives

A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light‐emitting diode. The laser shows a two‐stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The ‘double‐threshold’ phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface‐emitted output under optimized LED excitation.     

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.     

Gas-discharge XeF* (B→X) laser with high specific output energy

The discharge characteristics of the XeF* (BX) laser are investigated. The NF₃ and Xe partial pressure of the laser gas mixture and the total gas pressure have been varied. A highest specific output energy of 4.7 J/l with an efficiency of 0.5% was obtained from a X-ray preionized Ne/Xe/NF₃ gas mixture at 6 bar with single-pulse excitation through a multichannel spark gap.     

Diode-end-pumped continuous-wave Nd:YAG laser at 946 nm of single-frequency operation

We report a diode-end-pumped continuous-wave (CW) Nd:YAG laser at 946 nm of single frequency operation. A ring laser resonator was designed and the output coupler transmission was optimized based on the investigation of the influence of the output coupler transmission on the thermal lens effect induced by energy-transfer upconversion. A maximum output power of 1.5 W CW single-frequency laser at 946 nm was achieved. The stability of the laser output power was better than ±1% in the given four hours.     

Tunable dual wavelength emission and bandwidth narrowing of a laser diode array with a simple external cavity

We report on the performance of a commercial, non-AR-coated diode laser bar of 20 W output power, consisting of 20 emitters, which uses an external cavity to achieve tunable, dual-wavelength emission. The separation between the wavelength peaks can be continuously tuned from 0 nm to 5 nm. An output power of 2.9 W is achieved at 3.7 nm peak-to-peak separation and higher powers are achieved for less separation. This is the highest dual wavelength output power reported so far using a standard diode laser array. PACS 42.55.Px; 42.60.-v; 42.60.Da; 42.60.Fc     

Fiber Optic Coupling of CW Linear Laser Diode Array

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｌａｓｅｒｄｉｏｄｅａｒｒａｙ (ＬＤＡ )ｔｈａｔｈａｓｍｕｌｔｉｐｌｅｅｍｉｔｔｉｎｇｒｅｇｉｏｎｓｉｓａｐｅｒｆｅｃｔｄｅｖｉｃｅｔｏａｃｈｉｅｖｅｈｉｇｈｅｒｐｏｗｅｒｏｕｔｐｕｔｓｗｉｔｈａｎｉｎｃｒｅａｓｅｄｂｒｉｇｈｔｎｅｓｓ.ＴｈｅｈｉｇｈＣＷ ｐｏｗｅｒ ,ｈｉｇｈｂｒｉｇｈｔｎｅｓｓａｎｄｆｉｂｅｒｏｕｔｐｕｔｏｆａｌａｓｅｒｄｉｏｄｅｂａｒｃａｎｂｅａｐｐｌｉｅｄｉｎｍｅｄｉｃｉｎｅ ,ｍａｔｅｒｉａｌｓｐｒｏｃｅｓｓｉｎｇ ,ｓｏｌｉｄ ｓｔａｔｅｌａｓ…     

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.     

Variation of Xe concentration in a high pressure Ar/Xe laser with coaxial e-beam pumping

A series of measurements on the high pressure (up to 18 bar) coaxial e-beam pumped Ar/Xe laser has been made at high power loading (up to 25 MW/cm~2) for various Xe mole fraction in Ar. We found that the optimum laser gas composition in our system was 0.4% Xe in Ar which was independent of the total gas pressure. At the optimum gas composition the output energy increased with increasing total gas pressure up to 16 bar, but the intrinsic efficiency reached a maximum at the total gas pressure of 8 bar. It was also found that at the optimum power deposition for both the 2.63μm and 2.65μm transitions the ratio of the integrated optical energy to that of the 1.73μm transition had a minimum in most cases at the optimum gas mixture for various gas pressures. This ratio increased with increasing gas pressure. The experimental results suggested that besides the 2-body Xe quenching at high Xe fraction and electron collision mixing at high power depositions the heavy particle quenching from Ar at high gas press     

Optimization of facet coating for highly strained InGaAs quantum well lasers operating at 1200 nm

The optical output power of a laser diode can be enhanced by anti-reflection (AR) and high-reflection (HR) facet coatings, respectively, at the front and back facet. AR and HR coatings also serve the purpose of protection and passivation of laser diode facets. In this work, we have designed and optimized a single layer λ/4 thick Al₂O₃ film for the AR coating and a stack of λ/4 thick Al₂O₃/λ/4 thick Si bi-layers for the HR coating for highly strained InGaAs quantum-well edge emitting broad area (BA) laser diodes. Effect of the front and back facet reflectivities on output power of the laser diodes has been studied. The light output versus injected current (L–I characteristics) measurements were carried out on selected devices before and after the facet coatings. We have also carried out the numerical simulation and analysis of L–I characteristics for this particular diode structure. The experimental results have been compared and verified with the numerical simulation.     

Optimized operation of optically pumped NH3 laser emission at 12.08 μm and 12.81 μm

Based on the semi-classical density matrix equations, optimized operation of optically pumped NH₃ MIR laser emission at 12.08μm and 12.81μm was studied theoretically and experimentally. The effect of pump power, gas pressure and buffer gas N₂ on MIR output power were discussed in detail. Supported by theNatural Science Foundation of Guangdong Province, P.R. China.     

High power continuous wave Tm:YAP laser dual-end-pumped by laser diode at 795 nm

A high power continuous wave diode-pumped Tm:YAP laser at room temperature was presented in this paper. The Tm:YAP crystal with doped concentration of 3 at % for the experiment was c-cut with dimensions of 3 × 3 × 8 mm³. A 795 nm continuous wave laser diode in dual-end-pumped geometry was used to generate 1.94 μm laser output. At the pump power of 38.9 W, the highest output power reached 12.3 W by use of 15% output coupling, corresponding to optical conversion efficiency was 31.6% and the slope efficiency was 38.2%.     

200 mJ半导体端面泵浦MOPA激光器研究

采用高功率激光二极管阵列(LDA)端面泵浦Nd:YAG激光棒方式, 结合凸凹非稳腔的设计，获得20 Hz运转条件下小束散角激光输出平均能量约为83 mJ。以该激光为振荡源，同样采用LDA端面泵浦Nd:YAG激光棒的方式进行能量放大，组成LDA端面泵浦振荡-放大(MOPA)激光器，最终获得重频频率20 Hz、平均能量＞200 mJ、发散角＜2.1 mrad、能量波动＜±2.5%的脉冲激光输出。该激光器光光转换效率约为14.6%，体积为175×91×49 mm3，质量＜1 kg，激光经8倍发射天线后发散角＜0.3 mrad。     

Three-level operation of a diode-bar-pumped Yb:S-FAP laser

We present an all solid-state Yb:S-FAP laser system running on the three-level laser transition at 985 nm. The pump source was a high fill-factor laser diode bar, with the output reformatted using a two-mirror beamshaping system to produce a rectangular pump beam that focused to a square spot. A nearly on-axis multipassing system was used to obtain four pump passes through a 1.6 mm Yb:S-FAP laser crystal. Gain-switched three-level laser output was achieved with an efficiency of 4.3% with respect to incident pump power. Electro-optic Q-switching produced 0.12 mJ pulses for a pump pulse energy of 11 mJ. Intra-cavity second-harmonic generation yielded a maximum pulse energy at 492.5 nm of 12 μJ.