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We demonstrate dynamic modulation of a hybrid plasmonic-photonic crystal nanocavity through using monochromatic coherent acoustic phonons formed by ultrahigh-frequency surface acoustic waves to achieve strong optomechanical coupling. As a result, optical resonance wavelength shift and a large modulation bandwidth are shown at telecommunication wavelength for the hybrid nanocavity.

We propose dynamic modulation of a hybrid plasmonic-photonic crystal nanocavity using monochromatic coherent acoustic phonons formed by ultrahigh-frequency surface acoustic waves (SAWs) to achieve strong optomechanical interaction. The crystal nanocavity used in this study consisted of a defective photonic crystal beam coupled to a metal surface with a nanoscale air gap in between and provided hybridization of a highly confined plasmonic-photonic mode with a high quality factor and deep subwavelength mode volume. Efficient photon-phonon interaction occurs in the air gap through the SAW perturbation of the metal surface, strongly coupling the optical and acoustic frequencies. As a result, a large modulation bandwidth and optical resonance wavelength shift for the crystal nanocavity are demonstrated at telecommunication wavelengths. The proposed SAW-based modulation within the hybrid plasmonic-photonic crystal nanocavities beyond the diffraction limit provides opportunities for various applications in enhanced sound-light interaction and fast coherent acoustic control of optomechanical devices.

We demonstrate that the photonic band gaps in silicon slab waveguides are generated through the acousto-optic (AO) interaction. By exciting the acoustic eigenmodes of slab waveguides, the refractive indices and interfaces of silicon slab can be modulated periodically to perturb the guided optical waves and open up the photonic band gaps. We find that the occurrence of the strong forbidden effect to form the band gaps is due to nonlinear interactions between the guided optical and acoustic modes. Using the finite-element method, we calculate the photonic band structures of TE waves and TM waves under the perturbation of the lowest three acoustic eigenmodes, respectively. The results show that the fundamental symmetric acoustic slab mode can create Bragg photonic band gaps of tunable width. With generating acoustic-wave amplitude of 1.0 % of the slab thickness, photonic band gaps from 61.58 – 61.92 THz for TE and 89.10 – 89.24 THz for TM are demonstrated. Applications include the design of optomechanical and AO devices and micro and nanolasers.

We generate photonic bandgaps (PBGs) in dielectric slab waveguides by exciting their acoustic plate eigenmodes of submicron wavelength. We investigate the optical forbidden bands below the light line where the slab interfaces and index of refraction are periodically modulated by the acoustic fields. Results show that multiple scattering through the enhanced periodic acousto-optic (AO) interaction opens Bragg PBGs. A tunable bandgap width and transmittance are achieved. Transmitted optical waves are found to incur strong nonlinear modulation through AO interaction by a multiphonon exchange mechanism. The applications include tunable optomechanical and AO devices.