多模熔融拉锥光纤耦合器中自发四波混频过程的偏振分辨识别
Polarisation-resolved identification of spontaneous four-wave mixing processes in a multimode fused tapered fibre coupler
- University of Ottawa（渥太华大学）
- National Research Council of Canada（加拿大国家研究委员会）
- Nexus for Quantum Technologies, Department of Physics, University of Ottawa（渥太华大学物理系量子技术联盟）
- Département de physique et astronomie, Université de Moncton（蒙克顿大学物理与天文学系）
- Quantinuum
- Corning Incorporated（康宁公司）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过偏振分辨测量和相位匹配计算，识别了多模熔融拉锥光纤耦合器中的自发四波混频过程，区分了模内与模间产生机制，并理论预测了可产生偏振或复合纠缠的泵浦条件。
AI中文摘要：
集成量子光子学受益于直接在波导中产生光子对的光子对源，这些光子对可被高效地收集、路由和操控。本文研究由两根单模光纤制成的熔融拉锥光纤微耦合器中的自发四波混频（SFWM），并报告了四项贡献。第一，我们在此多模器件中观察到SFWM光子对：其椭圆形中心区域支持三种空间模式分布，每种模式具有两种偏振态，共提供六个导模；在约800 nm附近泵浦时，产生648/1048 nm和660/1021 nm两对光子。第二，由于多种允许的SFWM过程产生相似波长，且仅凭波长无法识别其来源，我们通过结合相位匹配计算、选择定则以及两种独立的偏振测量（符合率对泵浦偏振的依赖性和产生光子的偏振层析）来区分这些过程。第三，在当前几何模型内，我们发现660/1021 nm光子对由同偏振泵浦光子在完全发生在单个高阶模内的过程中产生，而648/1048 nm光子对由正交偏振泵浦光子在耦合基模和高阶模的模间过程中产生；两个过程的信号光子输出偏振相似，而闲频光子几乎正交。第四，将分析扩展到测量工作点之外，我们从理论上识别出由共同泵浦驱动的成对同时SFWM过程，这些过程可能根据泵浦波长产生偏振纠缠或复合空间-偏振纠缠。更广泛地，这项工作为在多模波导中当仅凭光谱信息不足时识别模间SFWM过程提供了实用策略。
英文摘要：
Integrated quantum photonics benefits from photon-pair sources that generate photons directly in waveguides, where they can be efficiently collected, routed, and manipulated. Here, we investigate spontaneous four-wave mixing (SFWM) in a fused tapered-fibre microcoupler formed from two single-mode fibres, and report four contributions. First, we observe SFWM photon pairs in this multimode device: its elliptical central region supports three spatial mode profiles, each with two polarisations, giving six guided modes, and pumping it near 800 nm yields two photon pairs at 648/1048 nm and 660/1021 nm. Second, because several allowed SFWM processes produce similar wavelengths and wavelength alone does not identify their origin, we distinguish the processes by combining phase-matching calculations and selection rules with two independent polarisation measurements: the dependence of the coincidence rate on pump polarisation and polarisation tomography of the generated photons. Third, within the present geometrical model, we find that the 660/1021 nm pair is generated by co-polarised pump photons in a process occurring entirely within a single higher-order mode, whereas the 648/1048 nm pair is generated by orthogonally polarised pump photons in an intermodal process coupling a fundamental and a higher-order mode; the signal photons from the two processes have similar output polarisations, while the idler photons are nearly orthogonal. Fourth, extending the analysis beyond the measured operating point, we theoretically identify pairs of simultaneous SFWM processes driven by a common pump that could generate either polarisation entanglement or composite spatial-polarisation entanglement, depending on the pump wavelength. More generally, this work provides a practical strategy for identifying intermodal SFWM processes in multimode waveguides when spectral information alone is insufficient.
