Phonon interaction with coupled photonic-plasmonic modes in a phoxonic cavity

Abstract

We present a theoretical investigation of the acousto-optic interaction in a two-dimensional phoxonic crystal cavity containing a metallic nanowire. The crystal is constituted by a square array of cylindrical holes in a TiO2 matrix containing a cavity inside which a gold nanowire is introduced. The optical modes of the cavity are therefore of combined photonic-plasmonic character. We calculate the strength of coupling between these modes and the localized phonons of the cavity, based on the “Moving Interface” mechanism of acousto-optic coupling. We discuss the coupling strength as a function of the size and position of the metallic nanowire and compare the results with those of a cavity without metallic particle.

Numerical Modeling of Acousto–Plasmonic Coupling in Metallic Nanoparticles

“…Both acoustic − and optical − characteristics are sensitive to many parameters such as the size, the shape, and the coupling between the nanoparticles and the surrounding medium. Exploring the interaction between acoustic vibrations and localized surface plasmons has large fundamental and technological interests. − For example, we can cite the development of multifunctional nanoagents integrating both tumor diagnosis and treatment functions . Numerical modeling, by making possible the comparison of many different options for optimization, is an essential tool in the field of engineering novel nanostructures with high performances. , …”

Nanomechanical modulation cavities of localized surface plasmon resonance with elastic whispering-gallery modes

“…Phonon modes supported by noble metal nanoparticles (NPs) have attracted particular attention since they interact with localized surface plasmon resonances (LSPRs), leading to a strong modulation of the plasmonic response. [1][2][3][4][5][6][7] Understanding this modulation is paramount for both fundamental and applied aspects. LSPRs are associated with the collective resonant oscillation of conduction electrons excited by an external electromagnetic field in metal NPs whose light confining properties make it possible to overcome the diffraction limit, which imposes the minimal dimensions of optical devices.…”

“…8 A significant amount of work has been conducted to study the strong acoustic vibration of metallic NPs by pump-probe 31 and Raman spectroscopies, 36 leveraging signal amplification near the LSPR mode. The modulation of a plasmon mode by an elastic mode has been studied for a wide set of metal NPs such as spheres, 37 cubes, 38 crosses, 39 cylindrical nanowires, 6 and nanorods. 4 To have an order of magnitude of strain, Soavi et al 4 estimated that the elongation of nanorods 150 nm long is in the order of 5 pm in a typical pump-probe experiment, which gives a strain of 3.3 × 10 −5 .…”

Hybrid plasmonic–phononic cavity design for enhanced optomechanical coupling in lithium niobate

“…(Liu et al 2018), Liu et al reported a plasmonic waveguide utilizing gap surface plasmons for producing high Brillouin gain even when the photoelastic property of the dielectric material is poor. As the mode area can go beyond the diffraction limit by forming the surface plasmons at the metal-dielectric interface, hybrid mechanical and plasmonic cavities may also be suitable for harvesting high-frequency phonons and enhancing g 0 (Benz et al 2016;Lin et al 2015;El-Jallal et al 2016;Mrabti et al 2016;Aspelmeyer et al 2014). Recently, a picocavity that produces a significantly enhanced g 0 between plasmonic mode and molecular vibrations (frequency in the THz range) has been reported (Benz et al 2016).…”