Yesharim Ofir, Izhak Shani, Arie Ady
School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel.
Nat Commun. 2025 Jul 15;16(1):6508. doi: 10.1038/s41467-025-61918-4.
Guiding light forms the backbone of numerous photonic circuits that allow complex, robust, and miniaturized light control. Commonly, guiding is achieved by modifying linear permittivity, resulting in a non-homogeneous linear medium. Here, we propose and experimentally realize photonic circuits in a homogeneous refractive index medium, where the guiding is driven entirely by nonlinear interaction, enabling dual-wavelength light beam guidance and optical control. This mechanism is analogous to spin current transport in sharp magnetic domain walls, where magnetization texture constitutes a spin-dependent potential. Using narrow custom-poled nonlinear photonic crystals, we guide frequency superposition beams that act as pseudo-spins over more than four Rayleigh lengths. We show that guiding properties depend on the relative phase between participating wavelengths, which can be optically switched on and off with an optical pump. Additionally, using two parallel-poled structures, we experimentally realize a pseudo-spin directional coupler, paving the way for numerous waveguiding hallmarks in a single nonlinear crystal and offering robust control over frequency superposition states of light. Finally, our findings show that it is possible to experimentally emulate complex, precise 2D magnetization domain wall structures, opening avenues for exploration that remain challenging in magnetic materials.
引导光构成了众多光子电路的核心，这些光子电路能够实现复杂、稳健且小型化的光控制。通常，引导是通过改变线性介电常数来实现的，从而形成一种非均匀线性介质。在此，我们提出并通过实验实现了在均匀折射率介质中的光子电路，其中引导完全由非线性相互作用驱动，实现了双波长光束引导和光学控制。这种机制类似于在尖锐磁畴壁中的自旋电流传输，其中磁化纹理构成了一个自旋相关势。利用窄定制极化非线性光子晶体，我们引导频率叠加光束，这些光束在超过四个瑞利长度上充当伪自旋。我们表明引导特性取决于参与波长之间的相对相位，该相对相位可以通过光泵浦进行光学开关。此外，使用两个平行极化结构，我们通过实验实现了一个伪自旋定向耦合器，为在单个非线性晶体中实现众多波导特性铺平了道路，并为光的频率叠加态提供了稳健控制。最后，我们的研究结果表明，有可能通过实验模拟复杂、精确的二维磁化畴壁结构，为在磁性材料中仍然具有挑战性的探索开辟了道路。
