In this paper, we study the possible parametric down-conversion processes in a type II phase-matched, Lithium Niobate ridge waveguide, designed to generate photon pairs in the telecommunication range. A quantum analysis of spontaneous parametric down-conversion (SPDC), first, with a pulsed Gaussian pump beam and second, with a pulsed, spatially anti-symmetric Hermite-Gaussian HG (1,0) pump beam predict the possible down conversion processes in each case. In case of the former, degenerate photon pairs are emitted at 1550 nm with the highest efficiency in the fundamental waveguide mode. While, in case of the latter, non-degenerate photon pairs in different higher-order spatial modes are generated. The joint spectral amplitude (JSA) analysis of these processes, prove that the generated photons pairs having orthogonal polarizations are negatively correlated. With multiple degrees of freedom, like polarization and spatial modes, such photons can be further harnessed towards modal-entangled and hyper-entangled photons for quantum information applications. This study involving the JSA is one of the first kinds, especially, to show the possibility of photon pairs generated in different spatial modes and polarization, after being incident with a spatially anti-symmetric pump beam in a ridge waveguide scenario.

中文翻译：

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SPDC 光子对在 ppLN 脊形波导中使用空间反对称泵浦光束

在本文中，我们研究了 II 型相位匹配铌酸锂脊形波导中可能的参数下变频过程，该波导旨在在电信范围内生成光子对。自发参数下变频 (SPDC) 的量子分析，首先使用脉冲高斯泵浦光束，然后使用脉冲、空间反对称 Hermite-Gaussian HG (1,0) 泵浦光束预测可能的下变频过程每个案例。在前者的情况下，简并光子对在 1550 nm 处发射，在基本波导模式中效率最高。而在后者的情况下，会生成不同高阶空间模式中的非简并光子对。这些过程的联合谱幅度 (JSA) 分析，证明产生的具有正交极化的光子对是负相关的。具有多个自由度，如偏振和空间模式，这些光子可以进一步用于量子信息应用的模态纠缠和超纠缠光子。这项涉及 JSA 的研究是第一类，特别是展示了在脊形波导场景中与空间反对称泵浦光束入射后，在不同空间模式和偏振中产生光子对的可能性。