Based on the second-order nonlinearity, we present a bidirectional tunable all-optical switch at C-band by introducing backward quasi-phase-matching technique in Mg-doped periodically poled lithium niobate (MgO:PPLN) waveguide with a nano-structure called multiple resonators. Two injecting forward lights and one backward propagating light interact with difference frequency generations. The transmission of forward signal and backward idler light can be modulated simultaneously with the variation

本文报道用准光波导方法测量了沉积在棱镜底面上的聚苯乙烯和聚醚砜薄膜,确定了这两种聚合物薄膜的折射率和薄膜厚度.并用偏振光测定了其双折射.薄膜折射率测量误差为±1×10~(-3),薄膜厚度测量误差为±0.01μm.

Length and girth are central to measure the size of tube shaped objects. This paper extends circular helical curves to general tubular shapes and proposes a novel method for measuring their length and girth. We call the extended circular helixes quasi-helical curves. A formal definition, as well as

Spectrum-Oriented FFBP Algorithm in Quasi-Polar Grid for SAR Imaging on Maneuvering Platform

论文：Stanford Doggo: An Open-Source, Quasi-Direct-Drive Quadruped 。这篇论文展示了 Stanford Doggo，它是一种准直接驱动（quasi-direct-drive）的四足机器人，具有很强的动态运动能力。该机器人能媲美或超过当前最优多足机器人的一般性能指标。且在垂直跳跃灵敏度上，即以平均垂直速度为指标，Stanford Doggo 能与表现最好的动物相媲美，并超过此前表现最好的机器人 22%。整体设计架构重点关注准直接驱动的设计方法。复现该机器人的硬件和软件都已经开源，只需要手工工具制造和组装就能完成，总成本低于 3000 美元。