Opt Lett. 2019 Jan 1;44(1):106-109. doi: 10.1364/OL.44.000106.
Silicon nitride (SiN) is commonly employed to integrate third-order nonlinear optical processes on a chip. Its amorphous state, however, inhibits significant second-order nonlinear response. Recently, second-harmonic generation enhancement has been observed in SiN waveguides after an all-optical poling (AOP) method. Here we demonstrate that, after AOP of a SiN waveguide, for up to 2 W of coupled pump power, the same telecom-band signal undergoes larger interband wavelength conversion efficiency, based on sum-frequency generation (SFG), than intraband wavelength conversion, based on four-wave mixing. We also confirm the appearance of a phase-matching condition after AOP by measuring the conversion bandwidth and efficiency of SFG at different pump wavelengths.
氮化硅（SiN）常用于在芯片上集成三阶非线性光学过程。然而，其非晶态抑制了显著的二阶非线性响应。最近，在采用全光极化（AOP）方法后，观察到 SiN 波导中的二次谐波产生增强。在此，我们证明了在 SiN 波导的 AOP 之后，对于高达 2 W 的耦合泵浦功率，基于和频产生（SFG）的同带间信号经历比基于四波混频的内带间波长转换更大的波长转换效率。我们还通过测量不同泵浦波长下 SFG 的转换带宽和效率，证实了 AOP 后的相匹配条件的出现。
