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A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd: YAG/Cr: YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26% (1δ) through the pre-pumped modulation technique. 相似文献
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In terms of the volume-integrated Poynting vector, we present a quantum field-theory investigation of the zitterbewegung (ZB) of photons, and show that this ZB occurs only in the presence of virtual longitudinal and scalar photons. To present a heuristic explanation for such a ZB, by assuming that the space time is sufficiently close to the flat Minkowski space, we show that the gravitational interaction can result in the ZB of photons. 相似文献
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外延单片式激光二极管抽运被动调Q微激光器 总被引:1,自引:0,他引:1
基于液相外延工艺,实现了一种结构新颖的单片式被动调Q微片激光器。采用了在激光介质Nd3 ∶YAG表面直接液相外延生长一层具有饱和吸收特性的Cr4 ∶YAG膜的微谐振腔的结构,由于是同质外延生长过程,能够确保饱和吸收体与增益介质间(Nd3 ∶YAG/Cr4 ∶YAG)良好的界面特性。采用光纤耦合激光二极管,在激光二极管输出为1W的抽运条件下,实现了峰值功率近千瓦、稳定重复频率在4kHz以上、脉宽1.8ns、TEM00单横模式、波长1.064μm的调Q脉冲序列输出。在对新型单片式微激光器的性能报道的基础上,阐述了外延单片式结构及其相应工艺的潜在优势。 相似文献
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选取91例经磁共振成像(MRI)检查后疑诊为脑胶质瘤患者作为研究对象,均行病理检查.以病理检查结果为准,11C-蛋氨酸正电子发射断层显像术(MET-PET/CT)诊断MRI疑诊脑胶质瘤敏感度为96.72%,特异度为96.67%,准确度为96.70%;标准化摄取值(SUV)、肿瘤/正常脑组织值(T/N)与WHO脑胶质瘤分... 相似文献