Second harmonic generation and sum frequency generation (SHG and SFG) provide effective means to realize coherent light at desired frequencies when lasing is not easily achievable. They have found applications from sensing to quantum optics and are of particular interest for integrated photonics at communication wavelengths. Decreasing the footprints of nonlinear components while maintaining their high up-conversion efficiency remains a challenge in the miniaturization of integrated photonics. Here we explore lithographically defined AlGaInP nano(micro)structures/Al₂O₃/Ag as a versatile platform to achieve efficient SHG/SFG in both waveguide and resonant cavity configurations in both narrow- and broadband infrared (IR) wavelength regimes (1300–1600 nm). The effective excitation of highly confined hybrid plasmonic modes at fundamental wavelengths allows efficient SHG/SFG to be achieved in a waveguide of a cross-section of 113 nm × 250 nm, with a mode area on the deep subwavelength scale (λ²/135) at fundamental wavelengths. Remarkably, we demonstrate direct visualization of SHG/SFG phase-matching evolution in the waveguides. This together with mode analysis highlights the origin of the improved SHG/SFG efficiency. We also demonstrate strongly enhanced SFG with a broadband IR source by exploiting multiple coherent SFG processes on 1 µm diameter AlGaInP disks/Al₂O₃/Ag with a conversion efficiency of 14.8% MW⁻¹ which is five times the SHG value using the narrowband IR source. In both configurations, the hybrid plasmonic structures exhibit >1000 enhancement in the nonlinear conversion efficiency compared to their photonic counterparts. Our results manifest the potential of developing such nanoscale hybrid plasmonic devices for state-of-the-art on-chip nonlinear optics applications.

当不容易实现激光发射时，二次谐波生成和总和频率生成（SHG和SFG）提供了实现所需频率下相干光的有效手段。他们发现了从传感到量子光学的应用，并且对于通信波长的集成光子学特别感兴趣。在保持集成光子小型化的同时，减少非线性元件的占位面积同时保持其高的上转换效率仍然是一个挑战。在这里，我们探索光刻定义的AlGaInP纳米（微）结构/ Al ₂ O ₃/ Ag作为通用平台，可在窄带和宽带红外（IR）波长范围（1300-1600 nm）的波导和谐振腔配置中实现有效的SHG / SFG。在基本波长高度约束的混合等离子体激元模式的有效激发允许有效SHG /将要在113纳米×250nm的横截面的波导上的深亚波长尺度实现SFG，具有模场面积（λ ² /135）在基本波长。值得注意的是，我们展示了波导中SHG / SFG相位匹配演变的直接可视化。这与模式分析一起突出显示了提高SHG / SFG效率的根源。我们还通过在直径为1 µm的AlGaInP磁盘/ Al上使用多个相干SFG工艺，证明了通过宽带红外光源大大增强的SFG。₂ O ₃ / Ag，转换效率为14.8％MW ^-1，是使用窄带红外光源的SHG值的五倍。在两种配置中，杂化等离激元结构与它们的光子对应物相比，在非线性转换效率方面表现出> 1000的增强。我们的结果表明，开发用于最新的片上非线性光学应用的纳米级混合等离子体激元器件的潜力。