Non-reciprocal light propagation is essential to control optical crosstalk and back-scatter in photonic systems. However, realizing high-fidelity non-reciprocity in low-loss integrated photonic circuits remains challenging. Here, we experimentally demonstrate a form of non-local acousto-optic light scattering to produce non-reciprocal single-sideband modulation and mode conversion in an integrated silicon photonic platform. In this system, a travelling-wave acoustic phonon driven by optical forces in a silicon waveguide spatiotemporally modulates light in a separate waveguide through linear interband Brillouin scattering. This process extends narrowband optomechanics-based schemes for non-reciprocity to travelling-wave physics, enabling large operation bandwidths of more than 125 GHz and up to 38 dB of non-reciprocal contrast between forward- and backward-propagating optical waves. The modulator operation wavelength is tunable over a 35-nm range by varying the optical drive wavelength. Such travelling-wave acousto-optic interactions provide a promising path toward the realization of broadband, low-loss isolators and circulators within integrated photonics.

不可逆的光传播对于控制光子系统中的光学串扰和反向散射至关重要。然而，在低损耗集成光子电路中实现高保真度不可逆性仍然具有挑战性。在这里，我们实验性地证明了一种非局部声光散射形式，可以在集成的硅光子平台中产生不可逆的单边带调制和模式转换。在该系统中，由硅波导中的光力驱动的行波声子通过线性带内布里渊散射在时空上调制单独波导中的光。该过程将基于非互易性的基于窄带光力学的方案扩展到行波物理，能够实现超过125 GHz的大工作带宽，以及正向和反向传播的光波之间高达38 dB的不可逆对比度。通过改变光驱的波长，调制器的工作波长可在35 nm范围内调节。这种行波声光相互作用为实现集成光子学中的宽带，低损耗隔离器和循环器提供了一条有希望的途径。