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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.


Related in: MedlinePlus

(a) Schematic of the hybrid plasmonic-photonic crystal nanocavity consisting of two missing circular holes in the cavity region. A nanobeam is set up above a metal (silver) substrate with an air-gap separation of distance d. (b) Geometry of the unit cell of the one-dimensional hybrid plasmonic-photonic crystal. The nanobeam is assumed to be made of silicon. The lattice constant a = 450 nm, the hole radius r = 135 nm (=0.3a), and the beam thickness h = 200 nm.
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f1: (a) Schematic of the hybrid plasmonic-photonic crystal nanocavity consisting of two missing circular holes in the cavity region. A nanobeam is set up above a metal (silver) substrate with an air-gap separation of distance d. (b) Geometry of the unit cell of the one-dimensional hybrid plasmonic-photonic crystal. The nanobeam is assumed to be made of silicon. The lattice constant a = 450 nm, the hole radius r = 135 nm (=0.3a), and the beam thickness h = 200 nm.

Mentions: Recently, hybrid optical nanocavities have been proposed to compress optical energy into deep subwavelength regions374344. The systems hybridize the photonic and surface plasmonic modes to form surface plasmon polaritons (SPPs), resulting in tighter spatial confinement of optical energy, higher local field intensity, and lower parasitic loss of metal4546. These properties can be used to enhance the efficiency of the optomechanical interaction between the photonic and phononic modes. In this study, we demonstrate the strong modulation of SPP modes at telecommunication wavelengths by surface acoustic waves (SAWs). The SPP modes were strictly confined to a nanocavity which consisted of a defect-containing photonic crystal beam and a metal surface with a nanoscale air gap in between, as shown schematically in Fig. 1a. The one-dimensional periodic beam contained defects in the middle by removing or modifying the air holes and was set up above a metal substrate with an air gap in between. The structure could then be designed to have both a high-Q factor and deep subwavelength mode volume Vm because the hybrid system supported a strong optical energy confined in the low-loss air gap region. Though the hybrid structure also introduced several photonic loss mechanisms, such as in-plane SPP radiation, evanescent coupling with the dielectric beam, and metal absorption47, it achieved a much higher Q/Vm ratio (or smaller mode volume Vm), which relates more directly than does the Q factor to the enhancement of photon-phonon interactions that allow for intense high-frequency acoustic disturbance. In this report, we will demonstrate the enhanced optomechanical modulation of the SPP mode in a nanocavity of high Q and low Vm using monochromatic coherent acoustic phonons localized on the silver substrate surface formed by high-frequency SAWs. In addition, we will systematically study the influential factors in such a system.


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 hybrid plasmonic-photonic crystal nanocavity consisting of two missing circular holes in the cavity region. A nanobeam is set up above a metal (silver) substrate with an air-gap separation of distance d. (b) Geometry of the unit cell of the one-dimensional hybrid plasmonic-photonic crystal. The nanobeam is assumed to be made of silicon. The lattice constant a = 450 nm, the hole radius r = 135 nm (=0.3a), and the beam thickness h = 200 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: (a) Schematic of the hybrid plasmonic-photonic crystal nanocavity consisting of two missing circular holes in the cavity region. A nanobeam is set up above a metal (silver) substrate with an air-gap separation of distance d. (b) Geometry of the unit cell of the one-dimensional hybrid plasmonic-photonic crystal. The nanobeam is assumed to be made of silicon. The lattice constant a = 450 nm, the hole radius r = 135 nm (=0.3a), and the beam thickness h = 200 nm.
Mentions: Recently, hybrid optical nanocavities have been proposed to compress optical energy into deep subwavelength regions374344. The systems hybridize the photonic and surface plasmonic modes to form surface plasmon polaritons (SPPs), resulting in tighter spatial confinement of optical energy, higher local field intensity, and lower parasitic loss of metal4546. These properties can be used to enhance the efficiency of the optomechanical interaction between the photonic and phononic modes. In this study, we demonstrate the strong modulation of SPP modes at telecommunication wavelengths by surface acoustic waves (SAWs). The SPP modes were strictly confined to a nanocavity which consisted of a defect-containing photonic crystal beam and a metal surface with a nanoscale air gap in between, as shown schematically in Fig. 1a. The one-dimensional periodic beam contained defects in the middle by removing or modifying the air holes and was set up above a metal substrate with an air gap in between. The structure could then be designed to have both a high-Q factor and deep subwavelength mode volume Vm because the hybrid system supported a strong optical energy confined in the low-loss air gap region. Though the hybrid structure also introduced several photonic loss mechanisms, such as in-plane SPP radiation, evanescent coupling with the dielectric beam, and metal absorption47, it achieved a much higher Q/Vm ratio (or smaller mode volume Vm), which relates more directly than does the Q factor to the enhancement of photon-phonon interactions that allow for intense high-frequency acoustic disturbance. In this report, we will demonstrate the enhanced optomechanical modulation of the SPP mode in a nanocavity of high Q and low Vm using monochromatic coherent acoustic phonons localized on the silver substrate surface formed by high-frequency SAWs. In addition, we will systematically study the influential factors in such a system.

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.


Related in: MedlinePlus