Single-photon imaging system with a fiber optic taper

We report a time-of-flight photon-counting imaging system in conjunction with a single-photon detector mounted with a fiber optic taper, which equivalently enlarges the active area of the single-photon detector by 100 times. The field of view of the imaging system is extended from ±0.57° to ±7° by using the fiber optic taper to collect the scattered photons. Since only a single avalanche photodiode is used, the noise level of the system is maintained at a low level. We demonstrate the scanning of the targets at a stand-off distance of 28 m with a centimeter depth resolution.     

光纤光栅选频掺Yb3+光纤激光器

以波分复用器(WDM),光纤光栅和自行研制的掺Yb~(3+)单模光纤,采用新颖的全光纤连接方案,实现了1060nm窄线宽、线形腔激光器的成功运转。对不同长度掺镱光纤(YDF)所构成的激光器进行了实验研究,发现9m为最佳长度。入纤抽运阈值功率约为30mW,当入纤功率达到最大值42.8mW时,得到最大激光输出8.8mW,半宽<0.5nm,相对于入纤抽运功率的斜率效率为70.4％。     

怎样消除移动通信网络中的乒乓位置更新效应

本文介绍了移动通信网络中的乒乓位置更新效应的产生原因及各种方案对其抑制或消除的原理和性能。然后引出一种既简单易行又能从根本上完全消除乒乓位置更新效应的位置管理模型。这种模型还能与最优位置更新策略和最优寻呼策略同时使用 ,使位置管理开销降到最低。