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arXiv · 2506.17167

Structured Harmonic Generation via Geometric Phase Enabled Pump Shaping

Ting-Ting Liu·Shi-Hui Ding·Chun-Yu Li·Hui Liu·Zhi-Han Zhu·Peng Chen·Yan-Qing Lu
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Abstract

Nonlinear optics is crucial for shaping the spatial structure of shortwave light and its interactions with matter, but achieving this through simple harmonic generation with a single pump is challenging. This study demonstrates nonlinear spin-orbit conversion using spin-dependent pump shaping via geometric phase, allowing the direct creation of desired structured harmonic waves from a Gaussian pump beam. By using the liquid-crystal flat optical elements fabricated with photoalignment, we experimentally produce higher-order cylindrically vectorial modes in second harmonic fields. We examine the vectorial spatial wavefunctions, their propagation invariance, and nonlinear spin-orbit conversion. Our results provide an efficient method for full structuring nonlinear light in broader harmonic systems, with significant applications in laser micromachining and high-energy physics.

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Ting-Ting Liu, Shi-Hui Ding, Chun-Yu Li, Hui Liu, Zhi-Han Zhu, Peng Chen, Yan-Qing Lu. 2025-06-20. Structured Harmonic Generation via Geometric Phase Enabled Pump Shaping. https://arxiv.org/abs/2506.17167

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