光子时间晶体中的二次谐波产生与非线性频率转换。

Second harmonic generation and nonlinear frequency conversion in photonic time-crystals.

作者信息

Konforty Noa, Cohen Moshe-Ishay, Segal Ohad, Plotnik Yonatan, Shalaev Vladimir M, Segev Mordechai

机构信息

Physics Department, Technion-Israel Institute of Technology, Haifa, Israel.

Solid State Institute, Technion-Israel Institute of Technology, Haifa, Israel.

出版信息

Light Sci Appl. 2025 Apr 2;14(1):152. doi: 10.1038/s41377-025-01788-z.

DOI:10.1038/s41377-025-01788-z

PMID:40175341

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11965301/

Abstract

We study the nonlinear process of second harmonic generation in photonic time-crystals, materials with refractive index that varies abruptly and periodically in time, and obtain the phase matching condition for this process. We find conditions for which the second harmonic generation is highly enhanced even in the absence of phase matching, governed by the exponential growth of the modes residing in the momentum gap of the photonic time crystal. Additionally, under these conditions, a cascade of higher-order harmonics is generated at growing exponential rates. The process is robust, with no requirement for phase-matching, the presence of a resonance or a threshold, drawing energy from the modulation.

摘要

我们研究了光子时间晶体中的二次谐波产生的非线性过程，光子时间晶体是折射率随时间急剧且周期性变化的材料，并获得了该过程的相位匹配条件。我们发现，即使在没有相位匹配的情况下，二次谐波产生也会显著增强，这是由光子时间晶体动量间隙中模式的指数增长所控制的。此外，在这些条件下，会以不断增长的指数速率产生一系列高阶谐波。该过程具有鲁棒性，不需要相位匹配、共振或阈值，而是从调制中获取能量。