In this paper we investigate potential of plasmonic nano switch as a result of Fano-resonance
observed in periodically arrayed silver (Ag) nanoparticles embedded over silicon (Si) on
insulator (SOI) substrate, by using 3D finite difference time domain (FDTD) method.
Structural parameters of the embedded silver nanoparticles were optimized giving rise to
plasmon modes in the device. We find that as the device is scanned for a range of wavelength
varying from visible to near infra-red, the transmission spectra exhibits Fano-line shape
asymmetry for input wavelength regime near 1.3 - 1.55micron, whereas normal resonating
peak is observed in the visible region. The optical properties of the switch reveal,
enhancement in transmission due to strong plasmonic Fano resonance between the
background and resonant processes. Sharp Fano-resonance, specific to interacting quantum
systems, is exhibited by the proposed embedded hybrid design of metal nanorods into Si,
which meets the condition required for high contrast switches and hence can be exploited as
per anticipated results. Fano resonance in this nanorod-substrate system can also be used for
designing nanoantennae, lasers, sensors, SERS etc.
A hybrid metal photonic crystal based nanostructured cavity and waveguide for the sub-wavelength confinement of light is proposed and it is shown that a bottom reflector is vital for the vertical emission from a silicon (Si) photonic crystal (PC) nanocavity. A photonic crystal slab of Si (ε<sub>d</sub>=11.56 or n<sub>d</sub>=3.4) with air holes and metal as an underlying substrate is chosen and three dimensional (3D) photonic bandgap for structure is calculated with plane wave expansion (PWE) method. Using finite difference time domain (FDTD) method, the transmission of a cavity mode as a function of Photonic crystal slab thickness is calculated and it is observed that the transmission increases with the increase in slab thickness at wavelength, λ = 1.55μm. Also, transverse electric field profiles (Ey) of the cavity mode has been shown and quality factor are calculated for the cavity and possible application in the area of PC light based emitters such as plasmonic lasers and single photon source is assessed.
We theoretically investigate compact plasmonic coupler based on metal nanopillar over silicon on insulator substrate
demonstrating routing of light at nanoscale. Proposed geometry demonstrates strong mode confinement, allows sharp
bends with low loss and easy integration on chip circuitry. The coupler is optimized for visible regime and can be tuned
for specific wavelengths. Plasmonic transverse magnetic (TM) modes are observed and examined using finite difference
time domain (FDTD) computations. Coupling length (Lc) and gap width (Wc) for the nanopillar assisted four-port
plasmonic coupling structure is optimized to give enhanced efficiency. The structure renders subwavelength light
manipulation overcoming conventional photonics with applications in plasmonic circuitry for nanoscale guidance of
light in data transmission, integrated chip design etc.
We examine the propagation of plasmonic TM (Transverse Modes) modes generated in the designed periodic array of
silver (Ag) embedded on silicon (Si) substrate. The properties of surface plasmons are tailored by altering the size of Ag
nanorods and its periodicity. Conventional waveguides cannot guide electromagnetic energy below the diffraction limit
of light, which can be overcome by texturing the metal or dielectric surface. In this hybrid design we have textured the
interface by placing metallic, Ag nanorods on Si substrate placed over bilayer system of glasses. This provides the
missing momentum required, since SPP modes always lay beyond the light line and has shown strong confinement of
light. Ag nanorods are structured at nano dimensions to control and manipulate surface plasmon polariton (SPP) propagation and thus open new possibilities in light matter interaction.
A plasmonic cavity incorporating surface plasmon polariton(SPP) mode is proposed to be used as infiltrated sensor
employing sub-wavelength confinement of light. Truly Plasmonic TM mode is obtained and the mode profile of the
Plasmonic Photonic Crystal Cavity (PPCC) structure is shown using three dimensional Finite Difference Time Domain
Method (3D-FDTD) method. The cavity length of the structure is optimized to obtain single mode localization of
resonating wavelength and the change in the cut-off wavelength is observed by varying refractive indices of the content
of air holes. A transverse magnetic (TM) Plasmonic bandgap of the structure is shown and hence, the transmission
spectra, Quality factor are calculated.
Plasmon like excitation is observed at the interface between
one-dimensional periodic array of air holes in
silicon (Si) with ferroelectric polyvinylidene fluoride (PVDF) as a substrate to obtain subwavelength
confinement of surface Plasmon modes at terahertz (THz) frequencies. A truly Plasmonic TM mode is obtained
confined at the interface of PVDF layer and the 1D perforated dielectric slab and the mode field distribution of
the structure is demonstrated using three dimensional (3D) Finite Difference Time domain Method (FDTD)
method. It is shown that PVDF are promising materials for strongly confined THz wave propagation in Surface
Plasmon photonic crystal. The transmission, confinement and hence the propagation length of the plasmonpolariton
like terahertz surface modes sustained by the structure are studied using Finite difference time domain
(FDTD) method. Further, the propagation characteristics of surface Plasmon polariton (SPP) which can be
controlled by the structure geometry is discussed.
One-dimensional (1D) surface plasmonic (SP) nanostructured cavity for the sub-wavelength confinement of light is
proposed. Since, the significant spatial confinement of the plasmonic structure is needed for the miniaturization of the
device, thin silver metal sheet is used to get plasmonic mode of the cavity. 1D plasmonic photonic crystal structure is
designed by placing a silver substrate film(εm) below the photonic crystal waveguide of one dimensional array of air
holes in Si (ε<sub>d</sub>=11.56 or n<sub>d</sub>=3.4) slab of finite thickness. TM mode with vertical electric field is investigated and it is
observed that the mode remains dominant in the structure. Further, surface plasmonic nano cavity defect mode is studied
by changing the cavity length which can be tuned for different wavelengths by changing the geometry of the structure.
Infiltrated liquid sensors based on a 2D photonic crystal waveguide were devised. This waveguide is designed by taking into account lowering of the radius of the central air holes in a single row and the optical resonance shifts due to refractive index change of these holes by selectively filling with different liquids. The transmission spectrum of the infiltrated liquid sensor was obtained with the use of a finite difference time domain method. At the working wavelength of 1550 nm, the waveguide mode gap edge shifts with sensitivity of 200 nm per refractive index unit. The mode gap shifts are consistent with dispersion diagrams.