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Strong Optomechanical Interaction in Hybrid Plasmonic-Photonic Crystal Nanocavities with Surface Acoustic Waves.

Lin TR, Lin CH, Hsu JC - Sci Rep (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: National Taiwan Ocean University, Department of Mechanical and Mechatronic Engineering, Keelung, 20224, Taiwan.

ABSTRACT
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.

No MeSH data available.


(a) Schematic of the perturbation of the crystal nanocavity using 3-GHz Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate. (b) Calculated SAW field distribution on the surface of the silver substrate with a total displacement amplitude /U/ equal to 4.5 nm. (c) The corresponding displacement components Uy and Ux of the SAW field, where the amplitude of Uy = 4.0 nm. (d) Variation of the displacements of Rayleigh SAWs along the depth from the silver substrate surface.
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f4: (a) Schematic of the perturbation of the crystal nanocavity using 3-GHz Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate. (b) Calculated SAW field distribution on the surface of the silver substrate with a total displacement amplitude /U/ equal to 4.5 nm. (c) The corresponding displacement components Uy and Ux of the SAW field, where the amplitude of Uy = 4.0 nm. (d) Variation of the displacements of Rayleigh SAWs along the depth from the silver substrate surface.

Mentions: On the basis of the high-Q and low-Vm plasmonic-photonic nanocavity, we then consider the optomechanical effect induced by high-frequency Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate, as shown schematically in Fig. 4a. In reality, one can employ piezoelectric material with comb-shape electrodes to electrically generate high-frequency SAW on the silver surface484950. For example, depositing piezoelectric thin film (e.g. ZnO) on the silver substrate or using crystalline piezoelectric substrate (e.g. LiNbO3) to support a silver layer, instead of using bulk silver substrate. The Rayleigh SAWs were elliptically polarized on the x-y plane, which effectively perturbed the SPP mode concentrated in the air gap to induce strong photon-phonon interaction. Figures 4b–d show the total displacement field /U/, vertical and horizontal displacement field components Uy and Ux on the silver substrate surface, and depth-dependent displacements of Rayleigh SAWs with a frequency fSAW of 3 GHz (where the depth was measured into the silver substrate). The SAW field could be generated as traveling or standing waves localized on the silver substrate surface and induce a periodic corrugated surface of period equal to the SAW wavelength λSAW to perturb the crystal nanocavity. The SAW perturbation gave rise to Bragg scattering of the electromagnetic field and optomechanical interaction. In this nanocavity scheme, the interface effect dominated the optomechanical interaction. In the present work, we focus on the interaction between SAW field and SPP cavity mode. However, mechanical oscillation in the photonic crystal beam may also contribute to the optomechanical interaction through the mechanism that SAW field perturbs the stored optical power in the nanocavity to have an optical power variation related to the SAW frequency and regenerate the mechanical oscillation of the photonic crystal beam515253. As a result, the interaction between the SPP cavity mode and mechanical oscillation may be enhanced.


Strong Optomechanical Interaction in Hybrid Plasmonic-Photonic Crystal Nanocavities with Surface Acoustic Waves.

Lin TR, Lin CH, Hsu JC - Sci Rep (2015)

(a) Schematic of the perturbation of the crystal nanocavity using 3-GHz Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate. (b) Calculated SAW field distribution on the surface of the silver substrate with a total displacement amplitude /U/ equal to 4.5 nm. (c) The corresponding displacement components Uy and Ux of the SAW field, where the amplitude of Uy = 4.0 nm. (d) Variation of the displacements of Rayleigh SAWs along the depth from the silver substrate surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561905&req=5

f4: (a) Schematic of the perturbation of the crystal nanocavity using 3-GHz Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate. (b) Calculated SAW field distribution on the surface of the silver substrate with a total displacement amplitude /U/ equal to 4.5 nm. (c) The corresponding displacement components Uy and Ux of the SAW field, where the amplitude of Uy = 4.0 nm. (d) Variation of the displacements of Rayleigh SAWs along the depth from the silver substrate surface.
Mentions: On the basis of the high-Q and low-Vm plasmonic-photonic nanocavity, we then consider the optomechanical effect induced by high-frequency Rayleigh SAWs propagating along the x-direction on the surface of the silver substrate, as shown schematically in Fig. 4a. In reality, one can employ piezoelectric material with comb-shape electrodes to electrically generate high-frequency SAW on the silver surface484950. For example, depositing piezoelectric thin film (e.g. ZnO) on the silver substrate or using crystalline piezoelectric substrate (e.g. LiNbO3) to support a silver layer, instead of using bulk silver substrate. The Rayleigh SAWs were elliptically polarized on the x-y plane, which effectively perturbed the SPP mode concentrated in the air gap to induce strong photon-phonon interaction. Figures 4b–d show the total displacement field /U/, vertical and horizontal displacement field components Uy and Ux on the silver substrate surface, and depth-dependent displacements of Rayleigh SAWs with a frequency fSAW of 3 GHz (where the depth was measured into the silver substrate). The SAW field could be generated as traveling or standing waves localized on the silver substrate surface and induce a periodic corrugated surface of period equal to the SAW wavelength λSAW to perturb the crystal nanocavity. The SAW perturbation gave rise to Bragg scattering of the electromagnetic field and optomechanical interaction. In this nanocavity scheme, the interface effect dominated the optomechanical interaction. In the present work, we focus on the interaction between SAW field and SPP cavity mode. However, mechanical oscillation in the photonic crystal beam may also contribute to the optomechanical interaction through the mechanism that SAW field perturbs the stored optical power in the nanocavity to have an optical power variation related to the SAW frequency and regenerate the mechanical oscillation of the photonic crystal beam515253. As a result, the interaction between the SPP cavity mode and mechanical oscillation may be enhanced.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: National Taiwan Ocean University, Department of Mechanical and Mechatronic Engineering, Keelung, 20224, Taiwan.

ABSTRACT
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.

No MeSH data available.