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arXiv 1801.02802physics.optics
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非对称涡旋光束宽带轨道angular momentum谱的控制产生、操纵和频率转换

Controlled generation, manipulation and frequency conversion of broadband orbital angular momentum spectrum of asymmetric optical vortex beams

Sabir Ul Alam, A. Srinivasa Rao, Anirban Ghosh, Pravin Vaity, G. K. Samanta

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Four pages, four figures
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摘要：

我们报告的产生和控制的可调谐，宽轨道角动量（OAM）光谱的涡旋光束。利用两个螺旋相位板将Yb光纤飞秒激光器输出的1064 nm高斯光束转换成l=1-6阶光学涡旋，转换效率> 95%。通过调节SPP相对于入射高斯光束轴的横向位移，我们已经将阶数为l的对称（强度分布）光学涡旋变换为阶数为l，l-1，l-2，.，0.虽然SPP的位置决定了OAM模式的权重，但是，随着SPP的移位，较高OAM模式的权重转移到较低OAM模式，最终产生高斯光束（l=0）。利用5毫米长的三硼酸铋晶体中的非对称涡旋的单程倍频，我们转移了泵浦OAM谱，l，l-1，l-2，.，0，进入高阶OAM模式的宽光谱，21，21 -1，21 -2，.，0在绿色波长，由于在非线性过程中的OAM守恒。我们还观察到，所有阶次的倍频涡旋的转换效率都随着泵涡旋不对称性的增加而增加。使用4.6 W的泵浦功率，我们已经产生了对称的涡旋在绿色波长的输出功率，1.2，0.76，0.47，0.4，0.32，和0.3 W和ls=2，4，6，8，10，和12，分别为。

英文摘要：

We report on generation and control of tunable, broad orbital angular momentum (OAM) spectrum of a vortex beam. Using two spiral phase plates (SPPs), we have converted the Gaussian beam of Yb-fiber femtosecond laser at 1064 nm into optical vortices of orders, l=1-6, with conversion efficiency >95%. By adjusting the transverse shift of the SPPs with respect to the incident Gaussian beam axis, we have transformed the symmetric (intensity distribution) optical vortex of order, l, into an asymmetric vortex beam of broad OAM spectrum of orders, l, l-1, l-2,..,0. While the position of the SPPs determines the weightage of the OAM modes, however, the weightage of the higher OAM modes transfer to lower OAM modes with the shift of SPPs and finally resulting a Gaussian beam (l=0). Using single pass frequency doubling of asymmetric vortices in a 5-mm-long bismuth triborate crystal, we have transferred the pump OAM spectra, l, l-1, l-2, ..., 0, into the broad spectra of higher order OAM modes, 2l, 2l-1, 2l-2, ...,0 at green wavelength, owing to OAM conservation in nonlinear processes. We have also observed that the conversion efficiency of the frequency-doubled vortices of all orders increases with the increase in the asymmetry of the pump vortices. Using pump power of 4.6 W, we have generated symmetric vortices at green wavelength of output powers, 1.2, 0.76, 0.47, 0.4, 0.32, and 0.3 W and orders of ls=2, 4, 6, 8, 10, and 12, respectively.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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