Electromechanical Brillouin scattering

In electromechanical Brillouin scattering (EBS), the elastic waves are electromechanically excited, instead of being stimulated by the optical forces in stimulated Brillouin scattering (SBS). The latest development of integrated EBS devices feature unprecedented high acoustic frequencies and strong co-confinement of the acoustic and optical modes within wavelength-scale structures, leading to significantly enhanced performance compared to their conventional counterparts, guided-wave acousto-optic devices. The new-generation integrated EBS devices are promising to reinvent guided-wave acousto-optics for “conventional” applications in optical beam steerers, tunable filters, frequency shifters, and single-sideband modulators. The EBS process is also promising to achieve efficient conversion between RF/MW and optical frequencies, with a wide range of novel applications from microwave photonics to quantum transduction between optical and microwave qubits. More interestingly, the exciting prospect of integrated nano-opto-electro-mechanical (NOEM) circuits that implement sophisticated sensing and information processing functionalities through EBS mechanisms in the classical and quantum regimes is attracting increasing research efforts. To provide a brief but comprehensive review of the new-generation integrated EBS devices, in this chapter, the electromechanical excitation of acoustic waves based on piezoelectric interdigital transducers (IDTs) is introduced first in Section 1, followed by a brief overview of EBS processes, configurations, and devices in Section 2. Finally, the chapter is concluded with the prospective applications of EBS devices in Section 3.