The ability to generate efficient giga-terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics.

中文翻译：

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光学双折射铁电体中的超快声光模转换。

飞秒激光能够产生有效的千兆兆赫兹相干声子的能力使声光成为超快光处理的有希望的候选者，它面临着电子设备对互补金属氧化物半导体技术固有的局限性。现代的声光设备，包括普通光波和异常光波之间的光学模式转换过程（反之亦然），仍然限制在兆赫兹范围内。在这里，我们使用飞秒激光脉冲在数十兆赫兹频率处产生的相干声波，揭示了模转换过程并显示了其在铁电材料（例如BiFeO3和LiNbO3）中的效率。除实验证据外，我们为由声光相互作用介导的全光学超快机制提供了完整的理论支持。