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设计了一个小型的激光二极管泵浦自聚焦透镜耦合的激光器,利用Cr4+:YAG晶体作为可饱和吸收体.研究了Nd:YAG\Cr4+:YAG键合晶体发射波长为1 064nm的被动调Q运转特性.在不同的输出率下得到了不同脉冲宽度以及不同重复频率的脉冲.当晶体温度在30℃时,重复频率范围在1.4到5kHz,脉冲宽度范围在3ns到5.2ns.在输出率为27%时最窄脉冲宽度为3ns、重复频率为4.18kHz时得到最大单脉冲能量为43.06μJ,相应的峰值功率为14.35kW,获得了的稳定脉冲序列同时获得了高度稳定的脉冲序列.此外,通过理论计算研究了键合晶体的热透镜焦距与泵浦功率的变化关系. 相似文献
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利用等离子体增强化学气相沉积系统沉积了碳纳米管或纤维,并用扫描电子显微镜研究了它们的生长和结构.为避免碳纳米管或纤维在生长过程中从衬底Si表面上脱落,先在Si表面上溅射沉积了金属过渡层Ti或Ta,然后再沉积催化剂NiFe.结果发现Ti和Ta过渡层对碳纳米管或纤维的结构有很大的影响.另外,还发现衬底Si放在支架的不同位置,碳纳米管或纤维的生长方向不同,这可能是由于辉光放电产生的非均匀电场所致.对不同过渡层和电场方向对碳纳米管或纤维生长的影响进行了分析和讨论. 相似文献
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Effects of N2 and glow discharge on growth behaviours of carbon nanotubes prepared by the hot filament chemical vapour deposition method 下载免费PDF全文
Carbon nanotubes (CNTs) are prepared by the hot filament chemical vapour deposition method using CH4 and H2 as reaction gases, and the growth behaviours are investigated by scanning electron microscopy and transmission electron microscopy. The results indicate that the CNTs prepared in the absence of N2 or glow discharge are bent; however, they are in an aligned state after introducing N2 into the chamber or forming glow discharge under a negative biased voltage. The results also indicate that the CNTs are of a bamboo-like structure when N2 is intruded as a reaction gas and the alignment degree of the CNTs grown under glow discharge is higher than that grown in N2. This illustrates that the nitric environment and glow discharge play important roles in the growth of CNTs. Combining with the theory related to alloy thermodynamics and collisions, we have analysed the growth mechanism of the CNTs in nitric environment and glow discharge. 相似文献
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A flasli-lamp-pumped Nd:YAG regenerative amplifier has been developed at 1.06 μm, seeded with 10-ps pulses from a diode-end-pumped and mode-locked Nd:YAG oscillator with homemade semiconductor saturable absorber mirror (SESAM). The pulse energy was amplified to 2 mJ by the regenerative amplifier at 10-Hz repetition rate. In two-stages amplifier the regenerative amplified pulse energy was amplified to 100 mJ, and 35-mJ double frequency at 532 nm was obtained by extra-cavity double frequency with a KTP crystal. 相似文献
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Ultrashort pulses were generated in passively mode-locked Nd:YAG and Nd:GdVO4 lasers pumped by a pulsed laser diode with 10-Hz repetition rate. Stable mode-locked pulse trains were produced with the pulse width of 10 ps. The evolution of the mode-locked pulse was observed in the experiment and was discussed in detail. Comparing the pulse evolutions of Nd:YAG and Nd:GdVO4 lasers, we found that the buildup time of the steady-state mode-locking with semiconductor saturable absorber mirrors (SESAMs) was relevant to the upper-state lifetime and the emission cross-section of the gain medium. 相似文献