Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Nat Commun. 2013;4:1944. doi: 10.1038/ncomms2943.
Nanoscale modal confinement is known to radically enhance the effect of intrinsic Kerr and Raman nonlinearities within nanophotonic silicon waveguides. By contrast, stimulated Brillouin-scattering nonlinearities, which involve coherent coupling between guided photon and phonon modes, are stifled in conventional nanophotonics, preventing the realization of a host of Brillouin-based signal-processing technologies in silicon. Here we demonstrate stimulated Brillouin scattering in silicon waveguides, for the first time, through a new class of hybrid photonic-phononic waveguides. Tailorable travelling-wave forward-stimulated Brillouin scattering is realized-with over 1,000 times larger nonlinearity than reported in previous systems-yielding strong Brillouin coupling to phonons from 1 to 18 GHz. Experiments show that radiation pressures, produced by subwavelength modal confinement, yield enhancement of Brillouin nonlinearity beyond those of material nonlinearity alone. In addition, such enhanced and wideband coherent phonon emission paves the way towards the hybridization of silicon photonics, microelectromechanical systems and CMOS signal-processing technologies on chip.
纳米级模态限制被认为可以极大地增强纳米光子硅波导中固有 Kerr 和 Raman 非线性效应。相比之下，涉及导波光与声子模式之间相干耦合的受激布里渊散射非线性在传统的纳米光子学中受到抑制，从而阻止了一系列基于布里渊的硅信号处理技术的实现。在这里，我们首次通过一类新型的混合光子-声子波导展示了硅波导中的受激布里渊散射。实现了可调谐行波前向受激布里渊散射-与以前的系统相比，非线性提高了 1000 多倍-产生了 1 到 18GHz 的强布里渊与声子耦合。实验表明，亚波长模态限制产生的辐射压力使布里渊非线性增强超过了材料非线性本身。此外，这种增强的宽带相干声子发射为硅光子学、微机电系统和 CMOS 信号处理技术在芯片上的混合铺平了道路。
