With the development of nanoscale transducers, surface acoustic wave (SAW) with frequencies above 10 GHz can now be excited on the optical waveguides. However, the fundamental mode is very difficult to be excited for SAW at ultrahigh frequencies. Moreover, as the wavelength of SAW is reduced to below the optical wavelength, the acoustic field across the optical waveguide can no longer be approximated as uniform but is spatially periodic. Here, we develop a discussion about integrated acousto-optic (AO) interaction at ultrahigh frequencies. The electromechanical coupling coefficients of different modes are evaluated for SAW at ultrahigh frequencies. The acousto-optic overlap is analyzed to evaluate integrated AO interaction for each given acoustic wavelength and optical waveguide size. An analytic model is presented for integrated AO interaction at ultrahigh frequencies. The research shows that it would be a trade-off for the design of an integrated AO device with ultrahigh frequencies.

随着纳米级换能器的发展，频率高于 10 GHz 的表面声波 (SAW) 现在可以在光波导上激发。然而，在超高频下，SAW 很难激发基模。此外，随着 SAW 的波长减小到低于光波长，光波导上的声场不再近似为均匀的，而是空间周期性的。在这里，我们讨论了超高频下的集成声光 (AO) 相互作用。评估了超高频下 SAW 不同模式的机电耦合系数。分析声光重叠以评估每个给定声波波长和光波导尺寸的集成 AO 相互作用。提出了用于超高频下集成 AO 相互作用的分析模型。研究表明，设计具有超高频的集成 AO 设备将是一种权衡。