论文标题
全庞加莱光束的单通行，非线性频率转换
Single-pass, nonlinear frequency conversion of full Poincaré beams
论文作者
论文摘要
完整的庞加莱（FP）梁是特殊的一类完全相关的光束，该光束是通过laguerre-gauss的同轴叠加和正交极化的基本高斯模式产生的，它在单光束中含有庞加尔球体表面上的所有可能的极化状态。尽管所有非常规极化状态的存在使FP梁对各种应用有用，但折射率对极化的依赖性限制了通过非线性频率过程通过电磁频谱的FP梁的有效产生。为了避免这种困难，我们使用两个连续的BIBO晶体，具有正交视轴，并在405 nm处生成一个超快的FP梁，平均功率高达18.3 mW，单通路转换效率为2.19％。使用Stokes参数和Stokes阶段，我们观察到C点和L线奇点的倍增和SHG过程中的轨道角动量。我们还设计了一种新技术，以估计泵和SHG FP梁的极化覆盖率，并观察到构成梁的强度重量的偏振覆盖率变化。有趣的是，SHG梁的极性覆盖率最高，对于超强度梁的相等强度重量的FP梁具有最高的极化覆盖率。我们验证了我们的实验结果与理论结果密切一致。
Full Poincaré (FP) beams, a special class of fully correlated beams generated through the coaxial superposition of a Laguerre-Gauss and fundamental Gaussian modes of orthogonal polarizations, contain all possible polarization states on the surface of the Poincaré sphere in a single beam. While the presence of all unconventional polarization states makes the FP beams useful for various applications, the dependence of the refractive index on the polarization restricts the efficient generation of FP beams across the electromagnetic spectrum through nonlinear frequency processes. To avoid such difficulty, we use two contiguous BIBO crystals with orthogonal optic axes and generate an ultrafast FP beam at 405 nm with average power as high as 18.3 mW at a single-pass conversion efficiency of 2.19%. Using Stokes parameters and Stokes phases, we observed the doubling of C-points and L-lines singularities and the orbital angular momentum in the SHG process. We have also devised a new technique to estimate the polarization coverage of the pump and SHG FP beams and observed the variation in polarization coverage with the intensity weightage of the constituting beams. Interestingly, the SHG beam has the highest polarization coverage for the FP beam of equal intensity weightage of the superposed beams. We validated our experimental results in close agreement with the theoretical results.
