Papers by Alexander A. Iskandar
Effective Medium Analysis of Stacked-Nanoparticles Array’s Optical Responses
Materials Science Forum
Metallic nanoparticle-based material is currently implemented in many photonics-based application... more Metallic nanoparticle-based material is currently implemented in many photonics-based applications such as biosensors, imaging, and color filter due to its remarkable properties called localized surface plasmon or LSP. Numerical methods are commonly used to calculate the optical responses arising from the nanostructure. However, a faster calculation can be provided by analytical methods. In this paper, we used an analytical calculation based on dipolar approximation and the transfer matrix method to calculate the optical responses of stacked-nanoparticles array on a dielectric substrate. Gold (Au) and silver (Ag) nanoparticles embedded inside a dielectric medium are considered. To validate the results, the analytical model was benchmarked to a finite element method (FEM) calculation. We found that the absolute difference of the absorbance peak of the analytical model to FEM calculation is less than 2 nm with the volume fraction of ~20% and it becomes better with a lower volume fract...
Study of Fano feature and its size dependent variations in TE – polarized light scattering by a silver nanorod
AIP Conference Proceedings, 2015
We report the result of a study on Mie Scattering of TE-polarized light by a silver nanorod for t... more We report the result of a study on Mie Scattering of TE-polarized light by a silver nanorod for the exploration of Fano phenomenon and its size dependent variations. This work is an extension of previous works of Rybin et al. on Fano resonances found in light scattering by a dielectric nanorod assuming a non-dispersive and non-absorptive permittivity of a large real value. The complex and frequency dependent of permittivity of silver is shown to cause significant changes in the scattered wave characteristics, although the calculated spectra do exhibit the Fano-like features. The result of this study further demonstrates that the scattered wave characteristics vary with the nanorod radius.
Lasers and Electro-Optics Society Meeting, Dec 2, 2004
Slow light (SL) states corresponding to wavelength regions near the bandgap edge of grated struct... more Slow light (SL) states corresponding to wavelength regions near the bandgap edge of grated structures are known to show strong field enhancement. Such states may be excited efficiently by well-optimised adiabatic transitions in grating structures, e.g., by slowly turning on the modulation depth. To study adiabatic excitations, a detailed investigation in 1D is performed to obtain insight into the relation between the device parameters and properties like field enhancement and modal reflection. The results enable the design of an adiabatic device for efficient excitation of SL states in 1D, and may be the basis for further research on 2D and 3D photonic crystals.
Journal of Mathematical and Fundamental Sciences, Feb 28, 2022
We report a study on the reflective performance of a dielectric metalattice formed by a one-dimen... more We report a study on the reflective performance of a dielectric metalattice formed by a one-dimensional periodic arrangement of silicon nanotubes. It was found that switching from transparent state to reflective state can be done by simply varying one optical parameter of the meta-lattice. The meta-lattice was shown to be capable of providing near-zero and near-unity reflectance at any desired wavelength, even in oblique incidence cases. The results are thus very promising for the development of future optical devices.
We perform a theoretical study of the optical dynamics of a hybrid system comprised of a closely ... more We perform a theoretical study of the optical dynamics of a hybrid system comprised of a closely spaced semiconductor quantum dot (SQD) and a metal nanoparticle (MNP). We show that, depending on the strength of the SQD-MNP coupling, the system can manifest bistability in the optical response. The SQD population demonstrate a hysteresis behavior upon sweeping adiabatically up and down the input intensity. We calculate the relaxation time required for the SQD population to reach its steadystate value and show that close to a critical intensity of the input, at which the SQD population switches from a lower to a higher value, the relaxation time is slowing down dramatically.
Polarization property of light scattered on dielectric nanorods at oblique incident angle
Journal of Nonlinear Optical Physics & Materials, 2019
We report the study of light polarization property upon scattering off a dielectric nanorod in wh... more We report the study of light polarization property upon scattering off a dielectric nanorod in which the direction of the incident light is at an angle with respect to the cylinder main axis. The numerical work is done on the basis of the cylindrical Mie theory. It is shown that for incident light with different polarization, the resulted scattering cross-section spectra will also show different characteristics with varying incident angles. For TE case, resonance splitting is observed due to excitation of a new resonance mode, while for TM case, resonance merging is observed. An interference effect between different resonance modes due to variation of incident angle is then resulted in suppression of backward scattering intensity for TM case. Meanwhile, for TE case, at illumination angle approaching grazing angle, a spectral range exists whereby the scattered wave’s angular intensity profile forms a perpendicular dipolar feature with different polarization. The reported results may ...
Core size and axial offset dependent extinction characteristics for silver nanotube and its application to directional sensing
Journal of the Optical Society of America B, 2019
We report the results of a study using the classical Mie theory and available experimental data o... more We report the results of a study using the classical Mie theory and available experimental data of Johnson and Christy [Phys. Rev. B6, 4370 (1972)] on the extinction spectra resulting from a transverse electric (TE) polarized wave incident upon a silver nanotube with a dielectric core. It is shown that the spectral changes separately induced by varied core radius (Rin) and the axial offset (d) are consistent with those reported for a gold spherical nanoshell calculated by the celebrated plasmon hybridization model, including the core offset induced symmetry breaking effect. This is followed by an analysis of the combined influences of Rin and d on the extinction efficiency Qext, which results in the optimal geometrical parameters of Rin=31.5 nm, d=16 nm, and Ag minimum shell thickness Δ=2.5 nm for the maximum Qext at the resonance wavelength of λ=756 nm. The different axial offsets are further shown to exhibit interesting variations of the angular distribution of the corresponding scattered wave intensity, which reveals significantly sensitive variations to different incident wave directions. The result has thus led to the following study for the exploration and demonstration of its potential development for sensing the direction of incoming TE polarized waves.
Journal of Optics, 2016
We theoretically investigate the nonlinear optical response of a heterodimer comprising a semicon... more We theoretically investigate the nonlinear optical response of a heterodimer comprising a semiconductor quantum dot strongly coupled to a metal nanoparticle. The quantum dot is considered as a three-level ladder system with ground, one-exciton, and biexction states. As compared to the case of a two-level quantum dot model, adding the third (bi-exciton) state produces fascinating effects in the optical response of the hybrid system. Specifically, we demonstrate that the system may exhibit picosecond and subpicosecond self-oscillations and quasi-chaotic behaviour under single-frequency continuous wave excitation. An isolated semiconductor quantum dot does not show such features. The effects originate from competing one-exciton and bi-exciton transitions in the semiconductor quantum dot, triggered by the self-action of the quantum dot via the metal nanoparticle. The key parameter that governs the phenomena mentioned is the ratio of the self-action strength and the bi-exciton shift. The self-oscillation regime can be achieved in practice, in particular, in a heterodimer comprised of a closely spaced ZnS/ZnSe core-shell quantum dot and a spherical silver nanoparticle. The results may have applications in nanodevices for generating trains of ultrashort optical pulses.
Enhanced energy confinement induced by metallic coating of central rod in square array photonic crystal of dielectric rods for TM light
Journal of Optics, 2014
We study the effects of a defect created by metallic coating of the central rod in a square latti... more We study the effects of a defect created by metallic coating of the central rod in a square lattice of dielectric rods for TM polarization lights. A calculation using the Plane Wave Expansion Method (PWE) in the supercell model shows that the photonic band structure and field distribution in the defect area varies with changing metallic layer thickness. The optimal energy localization is explored by varying the thickness of the metal layer. Enhancement of the energy confinement is described by the narrower spatial distribution profile of the energy with thicker metal coating. A more quantitative description, given in terms of confinement quality (CQ) defined by the normalized integrated intensity in the central rod, exhibits monotonous increase of CQ with growing metal layer thickness. The highest CQ value achieved is around 80% for a 3 × 3 supercell, which is considerably higher than the 44% optimal value achievable in the same dielectric PC structure with a defective central rod. Further calculation using the Extended Plane Wave Expansion Method for determining the imaginary part of the Bloch wave vector shows increasing with increasing metal coating thickness. The following analysis explains and corroborates the enhanced energy confinement effect.
Critical Points in the Bistable Optical Response of a Nanohybrid Comprising Semiconductor Quantum Dot and Metallic Nano Particle
Physical Review E, 2006
We have examined the rational solitons in the Generalized Coupled Mode model for a deep nonlinear... more We have examined the rational solitons in the Generalized Coupled Mode model for a deep nonlinear Bragg grating. These solitons are the degenerate forms of the ordinary solitons and appear at the transition lines in the parameter plane. A simple formulation is presented for the investigation of the bifurcations induced by detuning the carrier wave frequency. The analysis yields among others the appearance of in-gap dark and antidark rational solitons unknown in the nonlinear shallow grating. The exact expressions for the corresponding rational solitons are also derived in the process, which are characterized by rational algebraic functions. It is further demonstrated that certain effects in the soliton energy variations are to be expected when the frequency is varied across the values where the rational solitons appear.
Performance enhancement of a photonic crystal microcavity and related localization of evanescent Bloch waves
Physical Review B, 2011
A study is carried out to investigate the possible enhancement of photonic crystal (PC) microcavi... more A study is carried out to investigate the possible enhancement of photonic crystal (PC) microcavity performance induced by geometrical and permittivity variations in relation to localization of the associated evanescent Bloch wave. The study is focused on PCs of hexagonally packed dielectric rods. A numerical scheme formulated on the basis of Green's function method with multipole expansion approximation is employed
Journal of the Optical Society of America B, 2010
Optical Sensing and Switching Device Based on a Finite Deep Nonlinear Bragg Grating with a Mirror
Journal of Nonlinear Optical Physics & Materials, 2005
We investigate the detailed transition of the dark to antidark soliton-like states in a system of... more We investigate the detailed transition of the dark to antidark soliton-like states in a system of finite deep nonlinear Bragg grating equipped with a movable metallic mirror and illuminated by a continuous laser source. As reported previously, the transition can be induced mechanically by moving the mirror as well as optically by changing the light source intensity.
Dark, Antidark Soliton-Like Solutions and Their Connection in a Finite Deep Nonlinear Bragg Grating with a Mirror
Journal of Nonlinear Optical Physics & Materials, 2004
We report the results of our study on the in-gap soliton-like solutions in a system of a uniform ... more We report the results of our study on the in-gap soliton-like solutions in a system of a uniform finite deep nonlinear Bragg grating with a mirror and continuous light source on the opposite sides of the grating. The system was shown to exhibit a new feature consisting of homoclinic and heteroclinic orbits in phase plane associated with the in-gap bright and dark/antidark solitons respectively. The multi-valued connection between the dark and antidark solitons was explicitly displayed. It was further demonstrated that a transition from dark to antidark soliton could be affected by either changing the mirror position or changing the source intensity.
Journal of Nonlinear Optical Physics & Materials, 2003
A derivation of approximate analytical expressions for band edges ω± of the first band gap of a m... more A derivation of approximate analytical expressions for band edges ω± of the first band gap of a multilayer periodic structure is presented for both TE and TM waves at arbitrary angles of incidence. It is found that the approximate expressions give an excellent agreement with the numerical results as verified by the band edge variation with respect to the filling fraction [Formula: see text] and refractive index contrast Δn. The analytical expressions for the band edges are further employed to derive a semi numerical optimization of the relative gap width [Formula: see text] with respect to the filling fraction ν. The result is again shown to be in good agreement with the numerical result.
Analytic Study of Stationary Solitons in Deep Nonlinear Bragg Grating
Journal of Nonlinear Optical Physics & Materials, 2003
A study of nonlinear Bragg grating has been carried out using a modified scheme of approximation ... more A study of nonlinear Bragg grating has been carried out using a modified scheme of approximation originally proposed by Iizuka and de Sterke. A complete classification of the solitonic solutions in the system was given. We further demonstrated in this work the existence of in-gap dark and antidark soliton, in addition to the out-gap solutions reported previously. We also found at the boundaries in the bifurcation diagram, the large-amplitude out-gap antidark soliton and broad in-gap dark soliton.
Bright and Dark Solitary Waves in Kerr Medium with Higher Order Linear and Nonlinear Dispersions
Journal of Nonlinear Optical Physics & Materials, 2001
The existence of both bright and dark solitary wave solutions has been demonstrated for higher or... more The existence of both bright and dark solitary wave solutions has been demonstrated for higher order nonlinear Schrödinger (HNLS) equation containing up to the fourth order linear and the second order nonlinear dispersion. We found that the solutions are completely characterized by the material properties and free from arbitrary parameters in contrast to solutions of the pure NLS equation. The two types of solution were further shown to have complementary parameter space and share a singularity line of asymptotic values ±∞ for the solitary envelope velocities.
Effective Medium Formulation for Band Structure Design of a Finite One-Dimensional Optical Grating
Japanese Journal of Applied Physics, 2007
... Authors: Iskandar, AA; Yonan, W.; Tjia, MO; van de Voorde, I.; van Groesen, E. ... for tailor... more ... Authors: Iskandar, AA; Yonan, W.; Tjia, MO; van de Voorde, I.; van Groesen, E. ... for tailoring the transmission characteristics of a one-dimensional (1D) finite optical grating for its applications in the pass band and stop band regions without using anti reflection coating (ARC). ...
Japanese Journal of Applied Physics, 2006
A numerical analysis by means of transfer matrix method has been performed on finite one-dimensio... more A numerical analysis by means of transfer matrix method has been performed on finite one-dimensional photonic crystals consisting of two-layer repeated cells and two non-identical defect cells for the normal incident transverse electric (TE) wave. The study reveals a remarkable new feature showing that the variation of a photonic pass-band transmittance can be induced by varying the refractive index of one of the defect layer at practically the same peak frequency, which offers the potential application for single frequency sensing. The result further demonstrates the flexibility of tailoring the system parameters for application in the desired range of refractive index at the required sensitivity. It is also shown that the photonic pass-band (PPB) peak transmittance is generally less than unity in the index range considered, except for the case with the grating segment lengths ðM; N; LÞ satisfying the condition N ¼ M þ L. This peculiar feature is explained qualitatively in this work.
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Papers by Alexander A. Iskandar